Oncocytoma-Like Angiomyolipoma of the Kidney: A Closer Look into the Clinicopathologic, Immunohistochemical, and Molecular Characteristics of a Rare Entity with Review of the Literature

Introduction. Angiomyolipoma (AML) is a mesenchymal neoplasm that belongs to the perivascular epithelioid cell tumor family (PEComa). AMLs can be subtyped into several patterns dependent on cell type, morphology, and tissue composition. One of the patterns, oncocytoma-like AML is a rare entity with only three cases published in the literature. Case presentation. We present a case of a previously healthy 29-year-old woman who underwent a left partial nephrectomy secondary to a 4.6 cm heterogeneous renal neoplasm. Gross examination demonstrated a well-circumscribed renal mass. Modified Giemsa stain preparation showed oncocytic cells in syncytial pattern with ample granular cytoplasm and round nuclei with prominent nucleoli. Histology assessment showed an oncocytic neoplasm with interspersed adipose tissue. The tumor exhibited tubular architecture with the tubules lined by eosinophilic epithelioid cells with nuclear atypia and prominent nucleoli. Thick blood vessels with emanating epithelioid cells were present. High-grade histology features were not identified. The tumor cells were positive for HMB-45 and SMA and negative for PAX8, keratins, KIT, and vimentin. A diagnosis of oncocytoma-like AML was rendered. Next-generation sequencing (NGS) and RNA fusion were performed. NGS revealed no pathogenic variants and RNA fusion identified no rearrangements. Chromosomal copy number alterations were present in the long arm of chromosome 1 (1p) and chromosome 22. Conclusions. We describe and discuss the clinical, cytomorphologic, histologic, and molecular findings of oncocytoma-like AML, a rare renal neoplasm, and provide a review of the literature.

Epithelioid angiomyolipoma of the liver in a patient with Li-Fraumeni syndrome: a case report

BACKGROUND

Epithelioid angiomyolipoma (EAML) is a rare variant of angiomyolipoma that predominantly consists of epithelioid cells and belongs to the perivascular epithelioid cell neoplasm (PEComa) family. The majority of EAMLs arise in the kidneys, and primary hepatic EAML appears to be much less common than renal EAML. Most PEComas arise sporadically, but may be associated with tuberous sclerosis complex (TSC), an autosomal dominant genetic disorder characterized by germline mutations in the TSC1 or TSC2 genes. However, PEComas have previously been reported in five patients with Li-Fraumeni syndrome (LFS), which is an inherited cancer susceptibility disorder resulting from germline mutations in the TP53 tumor suppressor gene.

CASE PRESENTATION

We report a 49-year-old female patient with hepatic EAML and pancreatic cancer. Because she had previously been diagnosed with bilateral breast cancer at the age of 30, we performed a comprehensive genetic analysis to identify genetic alterations associated with any cancer predisposition syndrome. Whole-exome sequencing of a blood sample identified a heterozygous germline variant of TP53 (NM_000546.5):c.708C>A, and targeted next-generation sequencing of liver EAML and pancreatic cancer tissue samples demonstrated the same TP53 (NM_000546.5):c.708C>A variant in both. This, plus the patient's history of early-onset breast cancer, met the 2015 version of the Chompret criteria for diagnosis of LFS.

CONCLUSIONS

There have been very few case reports regarding the presence of PEComa in LFS, and to the best of our knowledge, this is the first report of EAML of the liver in a patient with LFS.

TSC2 inactivation, low mutation burden and high macrophage infiltration characterise hepatic angiomyolipomas

AIMS

Although TSC1 or TSC2 inactivating mutations that lead to mTORC1 hyperactivation have been reported in hepatic angiomyolipomas (hAML), the role of other somatic genetic events that may contribute to hAML development is unknown. There are also limited data regarding the tumour microenvironment (TME) of hAML. The aim of the present study was to identify other somatic events in genomic level and changes in TME that contribute to tumorigenesis in hAML.

METHODS AND RESULTS

In this study, we performed exome sequencing in nine sporadic hAML tumours and deep-coverage targeted sequencing for TSC2 in three additional hAML. Immunohistochemistry and multiplex immunofluorescence were carried out for 15 proteins to characterise the tumour microenvironment and assess immune cell infiltration. Inactivating somatic variants in TSC2 were identified in 10 of 12 (83%) cases, with a median allele frequency of 13.6%. Five to 18 somatic variants (median number: nine, median allele frequency 21%) not in TSC1 or TSC2 were also identified, mostly of uncertain clinical significance. Copy number changes were rare, but detection was impaired by low tumour purity. Immunohistochemistry demonstrated numerous CD68+ macrophages of distinct appearance from Küpffer cells. Multiplex immunofluorescence revealed low numbers of exhausted PD-1+/PD-L1+, FOXP3+ and CD8+ T cells.

CONCLUSION

hAML tumours have consistent inactivating mutations in TSC2 and have a low somatic mutation rate, similar to other TSC-associated tumours. Careful histological review, standard IHC and multiplex immunofluorescence demonstrated marked infiltration by non-neoplastic inflammatory cells, mostly macrophages.

Rare MDM2 amplification in a fat-predominant angiomyolipoma

Angiomyolipomas (AMLs) are triphasic tumors (smooth muscle, vascular and adipocytic components) with myomelanocytic differentiation, arising most commonly in the kidneys, which can show predominant epithelioid morphology and fat-predominant or fat-poor variants. Fat-predominant AMLs can show areas of hypercellularity and lipoblast-like cells, and these features can mimic well-differentiated liposarcoma (WDLS). To date, only one documented metastatic epithelioid AML showed unequivocal MDM2 amplification by fluorescence in situ hybridization. We describe our findings in a series of 35 AMLs including epithelioid, fat-poor, and fat-predominant variants, following interrogation of the MDM2 locus by FISH and CISH assays. MDM2 amplification was detected in 1 fat-predominant AML. Our findings demonstrate that rare MDM2 amplifications can occur in AMLs. We favor that this finding likely represents a "molecular bystander" event since these tumors are mainly driven by aberrations in the TSC1/TSC2 genes. Nevertheless, the presence of MDM2 amplification in a fat-predominant AML could present a potential diagnostic pitfall, particularly when confronted with the differential diagnosis of fat-predominant AML and WDLS in limited material from the retroperitoneum.

[Hereditary kidney cancers: The pathologist's view in 2020]

Hereditary predispositions to adult kidney tumors involve around 5% of tumors and include a dozen of autosomal dominant syndromes. The most frequent tumors encountered in these setting are clear cell renal cell carcinomas, papillary renal cell carcinomas, chromophobe renal cell carcinomas and angiomyolipomas. Their detection is essential in order to adapt individual care and perform genetic screening of at-risk relatives, especially in the national french network PREDIR, labeled by the National Cancer Institute and dedicated to hereditary predispositions to kidney tumors. Targeted genetic analysis, which was guided in particular by the renal tumor subtype, has recently evolved into genetic analysis using panels of genes. Pathologist contribution's remains however central in the diagnosis of hereditary forms since we currently have immunohistochemical biomarkers that allow us to diagnose two specifically hereditary entities: hereditary leiomyomatosis and renal cell carcinoma associated-renal cell carcinoma, associated with a loss of fumarate hydratase and succinate dehydrogenase-deficient renal cell carcinoma associated with a loss of succinate deshydrogenase B expression. These diagnoses must however be confirmed by the identification of pathogenic germline variation in the corresponding genes. Improvement of kidney tumors characterization has also lead to identify new subtypes, expanding the algorithm of renal tumors associated with hereditary setting. Here we aim to review all subtypes of adult renal tumors encountered in predisposition syndromes.

Renal Angiomyolipoma: Report of three cases with Regional Lymph Node Involvement and/or with Renal Cell Carcinoma

Aims and background

Angiomyolipomas (AMLs) are benign hamartoid tumors which frequently occur in tuberous sclerosis (TS). They may be manifest at different organ sites such as kidneys, lymph nodes, liver and lung and may be associated with renal cell carcinoma (RCC). The nature of multiple organ involvement in AML (metastasis versus multicentric synchronous tumors), the malignant transformation and the relation of AML to RCC have not been sufficiently clarified.

Study design

Three cases of renal AMLs in patients with tuberous sclerosis associated with lymphangioleiomyomatosis of the paraaortic lymph nodes and/or with RCC are reported. The concise clinical history of the patients as well as the findings of histology, immunohistochemistry and quantitative DNA analysis are presented.

Results

The multicentric form of AML and coincidence of renal AML and RCC were observed in 2 patients. AML and RCC were found within the same focus in one of the cases. RCCs were either aneuploid or “near diploid”, whereas one of the multicentric AMLs showed a discordant DNA ploidy pattern, namely aneuploidy in the kidney and diploidy in the lymph nodes.

Conclusions

The presented cases (all of them underwent periaortic lymphadenectomy) suggest that lymph node involvement in renal AML may be more frequent than expected (1-2% of all AMLs) on the basis of the few reported cases. The discordant DNA ploidy (renal versus lymph node lesions) observed in one of the cases with multicentric AML implies synchronous tumor growth at different sites rather than metastatic disease. The intimate coexistance of RCC and AML (RCC revealed by immunohistochemistry within a larger mass of renal AML) may indicate that malignant transformation of an AML should only be accepted, if such a coincidence is unequivocally excluded.

Treatment of Renal Angiomyolipoma and Other Hamartomas in Patients with Tuberous Sclerosis Complex

Tuberous sclerosis complex is an autosomal dominant genetic disease characterized by growth of benign tumors (hamartomas) in multiple organs, especially the kidneys, brain, heart, lungs, and skin. Tuberous sclerosis complex is usually caused by a mutation in either the tuberous sclerosis complex 1 or tuberous sclerosis complex 2 gene, resulting in constitutive activation of mammalian target of rapamycin signaling. Currently, mammalian target of rapamycin inhibitors are recommended in adult patients with tuberous sclerosis complex for the treatment of asymptomatic, growing renal angiomyolipoma that are >3 cm in diameter and pediatric or adult patients with brain lesions (subependymal giant cell astrocytoma) that either are growing or are not amenable to surgical resection. Clinical evidence suggests that systemic administration of a mammalian target of rapamycin inhibitor may provide concurrent improvements in multiple lesions and symptoms of tuberous sclerosis complex. With the major paradigm shift in consensus guidelines toward screening at diagnosis and ongoing monitoring and with the recent availability of an effective oral treatment, it is important that nephrologists have a thorough understanding of our role in the management of patients with tuberous sclerosis complex. Because the various manifestations of tuberous sclerosis complex typically emerge at different periods during patients' lifetimes, patients will need to be followed throughout their lives. Unlike brain and cardiac lesions, renal lesions are more likely to emerge as patients age and can grow at any time. Considerations regarding long-term medication administration for the potential control of multiple tuberous sclerosis complex manifestations will need to be addressed; these include the most appropriate starting dose, appropriate doses for tumor shrinkage versus prevention of regrowth, and management of adverse events. Best practices and potential obstacles for nephrologists treating patients with tuberous sclerosis complex who have multiple manifestations are considered.

Microsatellite analysis for differentiating the origin of renal angiomyolipoma and involved regional lymph node

Renal angiomyolipoma (AML) with the regional lymph node (LN) involved leads to a question of metastasis versus multicentric origin when their histology are similar. As the genomic instability is a common feature of cancer, we hypothesized that independently arising neoplasms in an individual patient would exhibit measurable genomic variation, facilitating the discrimination of tumor lineage and relatedness. Our study enrolled 12 patients who were diagnosed with nodal-involved renal AML at West China Hospital. Genomic DNA from kidney and lymph node lesion from individuals was analyzed through PCR-based analysis which using six microsatellite markers to identify discordant allelic variation. The results showed all 12 patients underwent surgical treatment and none suffered local recurrence or distant metastasis during the follow-up. Ten patients of the included cases showed a consistent trend that all corresponding to six microsatellite markers were detected in DNA from renal AMLs but were reduced or not observed in DNA from the paired LN. With this technique, a possible lineage relationship cannot be excluded between renal AMLs and LN. Thus when enlarged LN were found in images, active surveillance should be taken into consider; if enlarged LN were found intraoperatively, LN resection might be necessary to demonstrate their pathological nature.

Analysis of a Mouse Skin Model of Tuberous Sclerosis Complex

Tuberous Sclerosis Complex (TSC) is an autosomal dominant tumor suppressor gene syndrome in which patients develop several types of tumors, including facial angiofibroma, subungual fibroma, Shagreen patch, angiomyolipomas, and lymphangioleiomyomatosis. It is due to inactivating mutations in TSC1 or TSC2. We sought to generate a mouse model of one or more of these tumor types by targeting deletion of the Tsc1 gene to fibroblasts using the Fsp-Cre allele. Mutant, Tsc1^ccFsp-Cre+ mice survived a median of nearly a year, and developed tumors in multiple sites but did not develop angiomyolipoma or lymphangioleiomyomatosis. They did develop a prominent skin phenotype with marked thickening of the dermis with accumulation of mast cells, that was minimally responsive to systemic rapamycin therapy, and was quite different from the pathology seen in human TSC skin lesions. Recombination and loss of Tsc1 was demonstrated in skin fibroblasts in vivo and in cultured skin fibroblasts. Loss of Tsc1 in fibroblasts in mice does not lead to a model of angiomyolipoma or lymphangioleiomyomatosis.

A subset of fat-predominant angiomyolipomas label for MDM2: a potential diagnostic pitfall

Angiomyolipomas (AMLs) are typically benign mesenchymal tumors with variable histologic composition. Fat-predominant AMLs can mimic well-differentiated liposarcomas (WDLSs) both radiographically and histologically because of the abundance of fat with admixed atypical cells resembling lipoblasts. However, the treatment and prognosis of AMLs and WDLSs are vastly different. Immunohistochemistry for murine double minute 2 (MDM2) has been used to support a diagnosis of WDLS; however, MDM2 labeling has not been specifically evaluated in fat-predominant AMLs. Here, we evaluated MDM2 immunohistochemistry in 36 AMLs (including 14 conventional AMLs, 13 fat-predominant AMLs, 6 fat-rich AMLs, 3 epithelioid AMLs) and 10 WDLSs. In addition, we labeled cases for HMB45, calponin, or actin, which are immunostains traditionally used to label AML. We performed fluorescence in situ hybridization (FISH) for MDM2 amplification on selected cases. By immunohistochemistry, 14% (5/36) of AMLs were MDM2+, including 23% (3/13) of fat-predominant AMLs. All MDM2+ AMLs evaluated by FISH (n=4) were negative for MDM2 amplification. By immunohistochemistry, 90% of WDLSs were MDM2+, and both MDM2+ WDLSs evaluated by FISH (n=2) were MDM2 amplified. All 36 AMLs labeled with HMB45 and calponin or actin. No WDLS labeled with HMB45; however, 80% of WDLSs labeled with calponin or actin. Although uncommon, MDM2 labeling is seen in a subset of fat-predominant AMLs and is a potential diagnostic pitfall in the evaluation of fatty tumors of the retroperitoneum. HMB45 is more sensitive and specific for AML than calponin or actin, and an immunopanel containing both HMB45 and MDM2 may be warranted to distinguish between fat-predominant AML and WDLS in histologically ambiguous cases.

Whole Exome Sequencing Identifies TSC1/TSC2 Biallelic Loss as the Primary and Sufficient Driver Event for Renal Angiomyolipoma Development

Renal angiomyolipoma is a kidney tumor in the perivascular epithelioid (PEComa) family that is common in patients with Tuberous Sclerosis Complex (TSC) and Lymphangioleiomyomatosis (LAM) but occurs rarely sporadically. Though histologically benign, renal angiomyolipoma can cause life-threatening hemorrhage and kidney failure. Both angiomyolipoma and LAM have mutations in TSC2 or TSC1. However, the frequency and contribution of other somatic events in tumor development is unknown. We performed whole exome sequencing in 32 resected tumor samples (n = 30 angiomyolipoma, n = 2 LAM) from 15 subjects, including three with TSC. Two germline and 22 somatic inactivating mutations in TSC2 were identified, and one germline TSC1 mutation. Twenty of 32 (62%) samples showed copy neutral LOH (CN-LOH) in TSC2 or TSC1 with at least 8 different LOH regions, and 30 of 32 (94%) had biallelic loss of either TSC2 or TSC1. Whole exome sequencing identified a median of 4 somatic non-synonymous coding region mutations (other than in TSC2/TSC1), a mutation rate lower than nearly all other cancer types. Three genes with mutations were known cancer associated genes (BAP1, ARHGAP35 and SPEN), but they were mutated in a single sample each, and were missense variants with uncertain functional effects. Analysis of sixteen angiomyolipomas from a TSC subject showed both second hit point mutations and CN-LOH in TSC2, many of which were distinct, indicating that they were of independent clonal origin. However, three tumors had two shared mutations in addition to private somatic mutations, suggesting a branching evolutionary pattern of tumor development following initiating loss of TSC2. Our results indicate that TSC2 and less commonly TSC1 alterations are the primary essential driver event in angiomyolipoma/LAM, whereas other somatic mutations are rare and likely do not contribute to tumor development.

We performed comprehensive genome analysis of a kidney tumor called angiomyolipoma. These tumors are known to develop in most individuals who have Tuberous Sclerosis Complex (TSC) and those who have sporadic lymphangioleiomyomatosis (LAM), and are seen rarely in the general population. In these angiomyolipomas, we found consistent involvement of the TSC2 and TSC1 genes that are known to cause TSC, but very few (<5 on average) mutations elsewhere in the protein-coding regions. This is in stark contrast to other adult solid tumours that typically harbor hundreds to thousands of such mutations. Our results indicate that genetic alterations in TSC2/TSC1 are the primary and essential driver genetic events for development and progression of renal angiomyolipoma. Analysis of multiple angiomyolipomas from a single patient showed distinct genetic aberrations in the majority of samples, indicating that most of the tumors had developed independently. Branched clonal evolution was evident from the observation of three tumors that shared 2 mutations in addition to mutations private to each. Our results indicate that therapeutic approaches for treatment of patients with angiomyolipoma should focus on the consequences of TSC2/TSC1 loss, including but not limited to mTOR activation.

Immunohistochemistry of p53 and Ki-67 and p53 mutation analysis in renal epithelioid angiomyolipoma

BACKGOUND

Renal epithelioid angiomyolipoma (EAML) is a rare variant of AML (angiomyolipoma) and is often associated with aggressive behaviors. The pathogenesis of EAML has been poorly understood. We analyzed the expression of p53 and Ki-67 by immunohistochemistry (IHC) and investigated p53 mutation analysis in 11 cases of EAML in comparison to classical AML.

METHODS

P53 and Ki-67 expression status were determined by IHC staining. P53 mutation analysis was performed using bi-directional sequencing.

RESULTS

Renal EAML tumors were significantly associated with more severe to moderate nuclear atypia (100% vs. 36.4%, P = 0.004) and mitotic activity (90.9% vs. 27.3%, P = 0.008) compared with AML tumors. Out of 11 cases of EAML, 8 were positive for p53. There was only 1 case with positive p53 expression in AML cases and expression of p53 protein showed significant difference between EAML and AML tumors (72.7% vs. 9.1%, P = 0.008). In addition, there were 7 AML and 6 EAML cases harbored P72R mutation (SNP) in exon 4 of p53. Compared with AML cases, 2 out of 11 cases of EMAL showed more than 10% positivity for ki-67. The finding of stronger p53 expression in renal EAML might have contributed to their malignant behavior. However, the abnormal p53 expression cannot be entirely explained by p53 mutations in the exons examined.

CONCLUSIONS

Thus, the combination of immunohistochemical assessment of tumor antigens might improve our ability to predict the malignant outcome in EAML.

Rapamycin-insensitive up-regulation of adipocyte phospholipase A2 in tuberous sclerosis and lymphangioleiomyomatosis

Tuberous sclerosis syndrome (TSC) is an autosomal dominant tumor suppressor gene syndrome affecting multiple organs, including renal angiomyolipomas and pulmonary lymphangioleiomyomatosis (LAM). LAM is a female-predominant interstitial lung disease characterized by the progressive cyst formation and respiratory failure, which is also seen in sporadic patients without TSC. Mutations in TSC1 or TSC2 cause TSC, result in hyperactivation of mammalian target of rapamycin (mTOR), and are also seen in LAM cells in sporadic LAM. We recently reported that prostaglandin biosynthesis and cyclooxygenase-2 were deregulated in TSC and LAM. Phospholipase A2 (PLA2) is the rate-limiting enzyme that catalyzes the conversion of plasma membrane phospholipids into prostaglandins. In this study, we identified upregulation of adipocyte AdPLA2 (PLA2G16) in LAM nodule cells using publicly available expression data. We showed that the levels of AdPLA2 transcript and protein were higher in LAM lungs compared with control lungs. We then showed that TSC2 negatively regulates the expression of AdPLA2, and loss of TSC2 is associated with elevated production of prostaglandin E2 (PGE2) and prostacyclin (PGI2) in cell culture models. Mouse model studies also showed increased expression of AdPLA2 in xenograft tumors, estrogen-induced lung metastatic lesions of Tsc2 null leiomyoma-derived cells, and spontaneous renal cystadenomas from Tsc2+/- mice. Importantly, rapamycin treatment did not affect the expression of AdPLA2 and the production of PGE2 by TSC2-deficient mouse embryonic fibroblast (Tsc2-/-MEFs), rat uterine leiomyoma-derived ELT3 cells, and LAM patient-associated renal angiomyolipoma-derived "mesenchymal" cells. Furthermore, methyl arachidonyl fluorophosphate (MAFP), a potent irreversible PLA2 inhibitor, selectively suppressed the growth and induced apoptosis of TSC2-deficient LAM patient-derived cells relative to TSC2-addback cells. Our findings suggest that AdPLA2 plays an important role in promoting tumorigenesis and disease progression by modulating the production of prostaglandins and may serve as a potential therapeutic target in TSC and LAM.

[Hepatic epithelioid angiomyolipoma: a clinicopathologic analysis of 25 cases]

OBJECTIVE

To study the clinicopathologic features, immunophenotype, histological diagnosis and prognosis of hepatic epithelioid angiomyolipoma.

METHODS

Clinical data of 25 cases of hepatic epithelioid angiomyolipoma were collected along with follow-up study of the patients. The pathological features were documented and immunohistochemical study of various markers was performed with an emphasis on diagnosis and differential diagnosis.

RESULTS

Hepatic epithelioid angiomyolipoma was more commonly found in young women without characteristic clinical symptoms. Its morphological features were characterized by marked cytological atypia, relatively rare mitotic figures; radial distribution of tumor cells around the thin-walled blood vessels or muscular vessels; and the presence of common multinucleated giant cells and large ganglion-like tumor cells. The tumor cells expressed both melanoma cell markers (HMB45, MART-1) and smooth muscle cell markers (SMA). Tumor cells expressed various other markers including ER 16% (4/25), PR 32% (8/25), TFE3 24% (6/25) and p53 60% (15/25).

CONCLUSIONS

Hepatic epithelioid angiomyolipoma has variable morphological features and characteristic immunohistochemical phenotype. The differential diagnoses include a variety of tumors. The biological behavior of the tumor tends to be benign.

The analysis of mutations and exon deletions at TSC2 gene in angiomyolipomas associated with tuberous sclerosis complex

Angiomyolipomas (AMLs) are relatively rare hamartomatous or benign tumors that occasionally occur as part of tuberous sclerosis complex (TSC). Mutations in either of the two genes, TSC1 and TSC2, have been attributed to the development of TSC. Between 1994 and January 2009, 83 patients were diagnosed with AML at the Samsung Medical Center. In that group of patients, 5 (6%) had AML with TSC (AML-TSC). Mutational analysis of the TSC2 gene was performed using 7 samples from the 5 AML-TSC patients and 14 samples from 14 patients with sporadic AML without TSC (AML-non-TSC). From this analysis, mutations in TSC genes were identified in 5 samples from the AML-TSC patients (mutation detection rate=71%) and 3 samples from AML-non-TSC patients (mutation detection rate=21%). In the case of AML-TSC, 6 mutations were found including 3 recurrent mutations and 3 novel mutations, while in the case of AML-non-TSC, 4 mutations were identified once, including 1 novel mutation. Also MLPA analysis of the TSC2 gene showed that TSC2 exon deletion is more frequently observed in AML-TSC patients than in AML-non-TSC patients. This is the first mutation and multiplex ligation-dependent probe amplification (MLPA) analyses of TSC2 in Korean AMLs that focus on TSC. This study provides data that are representative of the distribution of mutations and exon deletions at TSC genes in clinically diagnosed AML-TSC cases of the Korean population.

A rare case of malignant epithelioid angiomyolipoma in multiple locations: multifocal disease or metastases?

BACKGROUND

Perivascular epithelioid cell tumors (PEComas), make up a family of extremely rare mesenchymal neoplasms, with characteristic morphological, immunohistochemical and molecular findings. Malignant PEComas and gastrointestinal epithelioid angiomyolipoma (E-AML) are especially rare. To the best of our knowledge E-AML have not been found in the breast. The difficulty in determining what constitutes optimal therapy for PEComas, owing to the sparse literature available, led us to report this rare case.

METHODS

We report a case of a 44-year-old woman, with a family history of multiple endocrine neoplasia syndrome (MEN) (gastrinoma, medullary thyroid cancer and parathyroid hyperplasia), affected by PEComa located in the kidney, stomach, ileum, liver and breast.

RESULTS

The renal, gastric, ileal and mammarian tumors were completely resected, with no evidence of local disease. Liver lesions were biopsied. The morphological and immunohistochemical findings confirm the diagnosis of PEComa.

CONCLUSION

On this basis it is difficult to determine if some E-AML are multifocal tumors or metastatic disease.

Analysis of the oestrogen response in an angiomyolipoma derived xenograft model

Angiomyolipomas are benign mesenchymal tumours of smooth muscle, blood vessels and fat which occur sporadically or associated with tuberous sclerosis and lymphangioleiomyomatosis (LAM), a rare cystic lung disease. Angiomyolipoma and LAM are caused by loss of function of either the tuberous sclerosis-1 or -2 genes resulting in activation of p70S6kinase (S6K1) and uncontrolled cellular proliferation. LAM and angiomyolipoma can be exacerbated by oestrogens but how this occurs is not understood. To address this question, we created a xenograft tumour system in nude mice using immortalised angiomyolipoma cells. Angiomyolipoma xenografts had active S6K1, p38, p42/44 MAPK and Akt; they grew more rapidly and had greater Akt phosphorylation after oestrogen treatment of tumour-bearing mice. Transcriptional profiling showed oestrogen induced 300 genes including extracellular matrix proteins, proteases, cell cycle regulatory proteins and growth factors including platelet derived growth factor-C (PDGF-C). Biologically active PDGF-C was produced by primary angiomyolipoma cells in culture and PDGF-C protein was present in the neoplastic smooth muscle cells of 5/5 human angiomyolipoma and 4/5 LAM tissues examined by immunohistochemistry. These findings suggest that the response to oestrogen in this model is mediated by activation of Akt and transcriptional events. This model may prove useful for studying the biology and effect of drugs on angiomyolipoma and diseases related to TSC.

Protein expression and mutational analysis of epidermal growth factor receptor in renal angiomyolipomas

Renal angiomyolipoma (AML) is a benign but progressive tumor that occasionally requires non-surgical therapy and there appears to be a possibility that epidermal growth factor (EGF) is associated with pathogenesis of renal AML. The response to gefitinib, anti-epidermal growth factor receptor (EGFR) agent and a prime example of target therapy, reportedly has been correlated with the presence of mutations within the tyrosine kinase (TK) domain of EGFR or the expression of its truncated form, EGFR variant III. Therefore the purpose of the present paper was to investigate EGFR protein expression and gene mutations in exons 18, 19 and 21 in 40 renal AML. No EGFR gene mutations of TK domain were detected in any of the 40 cases studied and strong immunostaining was found in 5% of the renal AML cases. The present findings indicate that in renal AML, anti-EGFR treatment may not be promising but that there is a possibility that EGFR is associated with renal AML pathogenesis.

Survivin expression in tuberous sclerosis complex cells

Tuberous Sclerosis Complex (TSC) is a tumor suppressor gene disorder with mutations of TSC1/TSC2 genes. This leads to the development of hamartomas that most frequently affect central nervous system, kidney, and skin. Angiomyolipomas are abdominal masses made up of muscle vessels and adipose tissues that grow mostly in proximity to kidneys and liver. Bleeding and kidney failure are the major justification for surgery. This study shows that angiomyolipoma-derived human smooth muscle TSC2-/- cells express the apoptosis inhibitor protein survivin when exposed to IGF-1. Survivin expression is also triggered whenever culture conditions perturb normal TSC2-/- cell function, such as the omission of EGF from the growth medium, the supplementation of anti-EGFR, blockade of PI3K and ERK, or inhibition of mTOR. Interestingly, single or simultaneous inhibition of PI3K by LY294002 and ERK by PD98059 does not prevent IGF-1-mediated survivin expression. Apoptogenic Smac/DIABLO, which is constitutively expressed by TSC2-/- A+ cells, is down-regulated by IGF-1 even in the presence of LY294002 and PD98059. These cells release IGF-1 by means of a negative feedback-regulated mechanism that is overrun when they are exposed to antibodies to IGF-1R, which increases the released amount by more than 400%. The autocrine release of IGF-1 may therefore be a powerful mechanism of survival of the tightly packed cells in the thick-walled vessels of TSC angiomyolipoma and in lymphangioleiomyomatosis (LAM) nodules. Future experimental therapies for TSC and LAM may result from the targeted inhibition of survivin, which may enhance sensitivity to TSC2 therapy.

Perivascular epithelioid cell tumor (PEComa) in the genitourinary tract

Perivascular epithelioid cell tumors (PEComas) are mesenchymal tumors composed of histologically, immunohistochemically, ultrastructurally, and genetically distinctive cells. PEComas have been described in different organs and are considered ubiquitous tumors. In this review we discuss recent informations related to PEComas in the genitourinary tract.

Differential Expression of Melanocytic Markers in Myoid, Lipomatous, and Vascular Components of Renal Angiomyolipomas

Context.—Renal angiomyolipoma is a tumor composed of varying amounts of fat, smooth muscle, and blood vessels. Characteristically, tumor cells express melanocytic markers such as HMB-45 and Melan-A. Recently, several other markers have been described as having excellent diagnostic sensitivity in cutaneous melanocytic lesions.

Objectives.—To compare the sensitivities of 5 melanocytic markers in renal angiomyolipoma and to study the expression patterns of these markers in the 3 different components of angiomyolipoma.

Design.—A tissue microarray of 20 renal angiomyolipomas was constructed. For each case, 3 cores containing fat, blood vessels, and smooth muscle were taken. The tissue microarray was then stained for HMB-45, Melan-A, tyrosinase, NK1-C3, and CD117.

Results.—HMB-45 was positive in 95%, Melan-A in 85%, NK1-C3 in 70%, tyrosinase in 50%, and CD117 in 40% of the cases. All (20/20) were positive for HMB-45 and Melan-A combined. These 5 markers had different sensitivities in the 3 components. HMB-45 was positive in 90%, 85%, and 80% of fat, smooth muscle, and blood vessel components, respectively; Melan-A in 70%, 60%, and 40%; NK1-C3 in 55%, 55%, and 45%; tyrosinase in 30%, 40%, and 10%; and CD117 in 20%, 40%, and 10%, respectively, of these 3 components.

Conclusions.—HMB-45 and Melan-A combined were positive in 100% of the renal angiomyolipomas. We recommend the use of these 2 markers in the workup of this entity, including those with predominantly 1 component. Other melanocytic markers are of limited use. A tissue block comprising predominantly fat or smooth muscle components should be used when performing melanocytic marker immunostain.

TSC2/PKD1 contiguous gene syndrome in an adult

A 48-year-old woman with a history of autosomal-dominant polycystic kidney disease (ADPKD), was found to have multiple renal angiomyolipomas on a pathological examination after nephrectomy. The clinical and pathological presentation is consistent with the diagnosis of TSC2/PKD1 contiguous gene syndrome, caused by the simultaneous loss of TSC2 and PKD1, the two major genes for tuberous sclerosis complex and ADPKD.

[Renal angiomyolipomatosis and pulmonary lymphangiomyomatosis. Its relationship with Bourneville syndrome]

INTRODUCTION

Renal angiomyolipomas are not very frequent in urologic activities. Pulmonary lymphangioleiomyomatosis is a rare disease that occurs mainly in women of reproductive age. Tuberous sclerosis shows lesions to different organs, including these both entities.

MATERIAL AND METHOD

We retrospectively analyze patients treated in our center. Three most representatives cases are reported. An indexed literature review is done, in order to establish a clinical protocol to manage these kinds of patients.

RESULTS

[corrected] Between 1990 and 2004, eight patients have been attended with an angiomyolipoma renal diagnostic. Five women (62%) and three men (38%). Medium age is 52,3y (29-69). In 3 of them (all women), it was also done a diagnostic of pulmonary lymphangioleiomyomatosis.

CONCLUSIONS

Bourneville syndrome is not very frequent. Associated angiomyolipomas usually are multiple, bilateral, with tender to grow and require more interventions. Previous diagnostic let us prevent future complications with vigilance, selective arterial embolization and nephron-spare surgery. Tumour size and the presence of symptoms are more decisive to decide best therapy alternative. Young patients with pulmonary lymphangioleiomyomatosis should be advise against pregnancy and the use of preparations containing estrogens.

Comparative genomic hybridization study of perivascular epithelioid cell tumor: molecular genetic evidence of perivascular epithelioid cell tumor as a distinctive neoplasm

Perivascular epithelioid cell tumor (PEComa) is a neoplasm composed chiefly of HMB-45-positive epithelioid cells with clear to granular cytoplasm and a perivascular distribution. Such tumors have been reported in different organs under a variety of designations. The cytogenetic features of these neoplasms have not been well studied. We collected 9 tumors (5 of kidney, 1 of prostate, 1 of urinary bladder, 1 of the pelvic cavity soft tissue, and 1 of uterus) from 8 patients, including one patient with tuberous sclerosis complex. The paraffin blocks of tumor tissue were submitted for comparative genomic hybridization analyses. Gross chromosomal aberrances were observed in all cases. The frequent imbalances were losses on chromosome 19 (8 cases), 16p (6 cases), 17p (6 cases), 1p (5 cases), and 18p (4 cases) and gains on chromosome X (6 cases), 12q (6 cases), 3q (5 cases), 5 (4 cases), and 2q (4 cases). The frequent deletion of 16p in which TSC2 gene is located indicates the oncogenetic relationship of PEComas with angiomyolipoma as a TSC2-linked neoplasm. From a molecular genetic perspective, the recurrent chromosomal alterations in both renal and extrarenal tumors further support the concept of PEComa as a distinctive tumor entity regardless of anatomic location.

Pathological and molecular analysis of sporadic hepatic angiomyolipoma

Hepatic angiomyolipoma (HAML) is an unusual mesenchymal lesion that can be misdiagnosed as hepatocellular carcinoma or sarcoma. We sought to better define the morphological variations and immunohistochemical and molecular features of this unusual tumor. Forty-nine sporadic HAMLs were investigated for immunopathologic characteristics with EnVision Plus. The clonal analysis was based on the methylation pattern of the polymorphic X chromosome-linked human androgen receptor gene, loss of heterozygosity (LOH), and microsatellite instability (MSI) detected with polymerase chain reaction using the MegaBACE 500 automatic system on microdissected tissues. Histologically, HAML is composed of a heterogeneous mixture of blood vessels, smooth muscle, and adipose cells. The myomatous or myoid cells were the most variable. Most of the tumor cells were positive for HMB-45 (100%) and SMA (100%). There was a typical monoclonal pattern in 35 of the 40 tumors. No LOH or MSI was found. Hepatic AML is a benign neoplasm with varied morphology and monoclonal growth. HMB-45 is the best marker available for diagnosis. Neither LOH nor MSI appears to play an important role in the pathogenesis of this tumor.

Detection of carbonic anhydrase-9 gene expression in peripheral blood cells predicts risk of disease recurrence in patients with renal cortical tumors

OBJECTIVES

To present extended follow-up on a cohort of patients with renal cortical tumors treated with partial or radical nephrectomy and preoperatively assess for carbonic anhydrase 9 tumor marker expression in the peripheral blood.

METHODS

All patients were originally enrolled in an institutional review board-approved study assessing the role of a reverse-transcriptase polymerase chain reaction peripheral blood assay designed to detect the tumor-specific gene carbonic anhydrase-9 (CA9). A total of 41 patients with renal cortical tumors confined to the kidney were enrolled at a single institution and assessed preoperatively with peripheral blood test for CA9 expression before undergoing partial or radical nephrectomy. A Kaplan-Meier estimated survival analysis and log-rank test were performed to determine whether detection of peripheral blood cells expressing the CA9 gene influences disease-free and disease-specific survival.

RESULTS

The median follow-up was 4.3 years. The median age was 71 years. Of the 41 patients, 26 were men and 15 were women. The estimated 5-year disease-free survival for patients with detectible expression of the CA9 gene in the peripheral blood was 39.5% compared with 88.1% for patients without detection of the CA9 gene (P = 0.048). On bivariate analysis, disease-free survival correlated with histologic type, tumor diameter, and tumor grade.

CONCLUSIONS

The expression of the tumor-specific marker CA9 in the peripheral blood is associated with decreased disease-free survival in patients with renal cortical tumors. This is the first study reporting on the prognostic value of this peripheral blood-based tumor marker for kidney tumors.

De novo concurrent papillary renal cell carcinoma and angiomyolipoma in a kidney allograft: evidence of donor origin

In the general population, renal cell carcinoma (RCC) is a relatively common neoplasm; however, the papillary RCC subtype is infrequent and represents only 10 to 15% of all RCC. Angiomyolipoma is a well-known common benign tumor. The occurrence of RCC in association with angiomyolipoma is a rare event, with only approximately 50 cases reported in the nontransplantation setting. In transplant recipients, RCC can develop in native kidneys, but its occurrence "de novo" in the renal allograft is very rare with an estimated incidence of less than 0.5%. We report here the case of a 39-year-old woman who underwent cadaveric renal transplantation in 1990. No lesion was observed in the allograft during the pre- and perioperative period or on early postoperative ultrasounds. No graft rejection occurred under a standard triple immunosuppressive therapy. Thirteen years later, during a routine ultrasonography, 2 solid masses were discovered in the allograft, both of them richly vascularized. She underwent allograft nephrectomy and the histologic findings revealed that one of the tumors was a chromophilic (type 1) papillary RCC (2.5 cm in diameter) and the other, an angiomyolipoma (1.5 cm). Microsatellite analysis of the allograft, as compared with the recipient peripheral blood leukocytes, demonstrated that the 2 tumors (1 malignant and 1 benign) were of donor origin. To our knowledge, this is the first report of de novo concurrent papillary RCC and angiomyolipoma in a renal allograft.

Isolation and growth of smooth muscle-like cells derived from tuberous sclerosis complex-2 human renal angiomyolipoma: epidermal growth factor is the required growth factor

Tuberous sclerosis complex (TSC) is a tumor suppressor gene disorder characterized by mutations in the TSC1 or TSC2 genes. These mutations lead to the development of benign tumors involving smooth muscle cells, causing life-threatening lymphangioleiomyomatosis. We isolated and characterized two types of cells bearing a mutation in TSC2 exon 18 from a renal angiomyolipoma of a TSC patient: one population of alpha-actin-positive smooth muscle-like cells with loss of heterozygosity for the TSC2 gene (A(+) cells) and another of nonloss of heterozygosity keratin 8/18-positive epithelial-like cells (R(+) cells). Unlike control aortic vascular smooth muscle cells, A(+) cells required epidermal growth factor (EGF) to grow and substituting EGF with insulin-like growth factor (IGF)-1 failed to increase the cell number; however, omission of EGF did not cause cell loss. The A(+) cells constantly released IGF-1 into the culture medium and constitutively showed a high degree of S6K phosphorylation even when grown in serum-free medium. Exposure to antibodies against EGF and IGF-1 receptors caused a rapid loss of A(+) cells: 50% by 5 days and 100% by 12 days. Signal transduction mediated by EGF and IGF-I receptors is therefore involved in A(+) cell survival. These results may offer a novel therapeutic perspective for the treatment of TSC complications and lymphangioleiomyomatosis.

KIT expression in normal and neoplastic renal tissues: Immunohistochemical and molecular genetic analysis

Renal chromophobe cell carcinomas (ChCC) and oncocytomas express KIT. This character seems to reflect their common histogenesis from distal nephrons. In the normal kidney, however, the expression and localization of KIT are unclear. KIT expression in angiomyolipoma and congenital mesoblastic nephroma (CMN), is still controversial. c-kit mutations are reportedly rare in ChCC, but there is little information in other renal neoplasms, and no reported data on mutations of platelet-derived growth factor receptor (PDGFR). In order to address these issues the authors examined five ChCC, five oncocytomas, seven papillary cell carcinomas, two collecting duct carcinomas, 12 angiomyolipomas, and three CMN, as well as 10 normal renal tissues. In the normal kidney KIT was specifically expressed in the distal nephrons. Nine of 12 (75%) angiomyolipomas contained scattered KIT-positive cells, whereas all three CMN were completely negative for KIT. The presence of KIT-positive cells in angiomyolipomas was likely to correspond to that of melanocytic marker-positive cells, which mainly showed epithelioid morphology. Polymerase chain reaction-single-strand conformation polymorphism showed no evidence of mutations of c-kit or PDGFR in any of the tumors examined.

Tuberous sclerosis and the kidney: from mesenchyme to epithelium, and beyond

The renal manifestations of tuberous sclerosis complex (TSC) are remarkably diverse, including polycystic kidney disease, oncocytomas, renal cell carcinomas, and both benign and malignant angiomyolipomas. All of these occur in children as well as adults with TSC. Benign angiomyolipomas, which can cause spontaneous life-threatening hemorrhage, are by far the most prevalent and the greatest source of morbidity. What is particularly unusual about TSC, setting it apart from virtually all other inherited forms of renal disease, is the abnormalities of both mesenchymal cells (angiomyolipomas) and epithelial cells (cysts, oncocytomas, and carcinomas). Recently, the TSC1/TSC2 protein complex was shown to inhibit the kinase mTOR (mammalian target of rapamycin). This places TSC1/TSC2 at center stage in signaling pathways that regulate cell growth. Furthermore, recent advances in TSC1/TSC2 signaling open the door for targeted therapy for TSC patients. Here, we will address the genetic, cellular and biochemical mechanisms that may contribute to the unusually broad spectrum of renal disease in cells with TSC1 or TSC2 mutations, and consider how the TSC signaling pathways may be linked to other renal diseases such as polycystic kidney disease and renal cell carcinoma.

Atypical Angiomyolipoma of Kidney in a Patient With Tuberous Sclerosis: A Case Report With p53 Gene Mutation Analysis

Angiomyolipoma (AML) is the most common benign mesenchymal tumor of the kidney. It belongs to the family of perivascular epithelioid cell tumors and is typically composed of blood vessels, adipose tissue, and smooth muscle– like cells, which are characteristically positive for HMB-45. Results of recent studies suggest that p53 mutation may play an important role in AML progression. Here, we describe a locally destructive renal AML in a patient with tuberous sclerosis. The tumor consisted of mostly epithelioid cells with marked nuclear pleomorphism and frequent mitoses and was positive for HMB-45. The diagnosis of atypical epithelioid AML was made. Codon alteration in the p53 gene was not detected, despite focal p53 immunoreactivity and single nucleotide polymorphism at exon 6. Our finding indicates no definite link between p53 abnormalities and the atypical appearance of AML. To the best of our knowledge, this is the second renal AML case investigated for p53 mutations.

Estrogen enhances whereas tamoxifen retards development of Tsc mouse liver hemangioma: a tumor related to renal angiomyolipoma and pulmonary lymphangioleiomyomatosis

Pulmonary lymphangioleiomyomatosis and abdominal angiomyolipoma are related lesions for which there is no authentic animal model. Both of these proliferative lesions occur in sporadic patients, and at much higher frequency in patients with tuberous sclerosis, which is due to mutations in the TSC1 and TSC2 genes. Tsc1+/- and Tsc2+/- mice frequently develop liver hemangioma. We found that the Tsc mouse liver hemangioma are composed predominantly of endothelial cells but with a smooth muscle component, and express HMB45 antigen, estrogen receptor, and progesterone receptor, similar to lymphangioleiomyomatosis and angiomyolipoma. Estrogen treatment significantly accelerated the development of liver hemangioma in Tsc1+/- female mice, with 91% having liver hemangioma and 55% having severe lesions by 7 months of age. Similarly, an increased frequency and severity of liver hemangiomas was seen in Tsc1+/- males treated with estrogen. In contrast, tamoxifen treatment for 9 months significantly reduced the frequency and severity of hemangiomas in Tsc1+/- female mice. In addition, estrogen treatment significantly increased serum vascular endothelial growth factor levels in Tsc1+/- mice, whereas tamoxifen reduced vascular endothelial growth factor levels. These mouse model observations indicate the importance of estrogen signaling in vivo for the growth of tuberous sclerosis lesions, suggesting the possible benefits of tamoxifen therapy for the treatment of angiomyolipoma and lymphangioleiomyomatosis.

Multifocal angiomyolipoma affecting the liver and lung without tuberous sclerosis

The occurrence of angiomyolipoma (AML) in tissue other than the kidney is uncommon, as is multiple AML developing exclusively in organs other than the kidney. This report describes a case in which AML occurred multifocally in the liver and lung, but spared the kidney, and which might have been associated with tuberous sclerosis complex (TSC). A Japanese woman underwent a partial hepatectomy for a suspected malignant liver tumour at the age of 57. The tumour consisted predominantly of a trabecular arrangement of myoid cells with a sinusoidal pattern and inflammatory cell infiltration, and was diagnosed as a primary liver AML by HMB-45 immunoreactivity. Five years later, multiple nodules were found in both lungs, for which video assisted thoracic surgery was performed. The tumour showed a mixture of epithelioid cells containing HMB-45 positive material and mature lipocytes, and was subsequently diagnosed as AML. Molecular analysis of both lesions showed no allelic loss of the TSC1 and TSC2 regions. Molecular analysis of the tumours ruled out an association with TSC, and both liver and lung lesions displayed benign histological features, so that these were probably multifocal lesions of AML without TSC.

[Angiomyolipoma--its role in prenatal diagnosis of tuberous sclerosis]

Tuberous sclerosis (TSC) is a frequent hereditary autosomal-dominant disease characterised by hamartomas developing in many organs. The disorder is caused by mutations affecting either of the tumor-suppressor genes, TSC1 and TSC2. Tumorogenesis is triggered by the loss of second functional gene copy, mostly accompanied by loss of heterozygosity (LOH) of flanking polymorphic markers. Search for causing mutations is very laborious, time consuming and low effective. Prenatal diagnosis is often hampered by lack of detection of causing mutation. Detection of LOH in hamartomatous tissue suggests which gene is involved in particular case of disease and specifies which of homologous chromosomes carries germinal mutation. Examination of LOH is useful for prenatal diagnostics especially when time is lacking due to patient's pregnancy or in case of mutation screening failure.

[Angiomyolipoma of the kidneys as a rare cause of retroperitoneal hemorrhage. Two case reports with tuberous sclerosis Bourneville-Pringle]

Tuberous sclerosis (Bourneville-Pringle-disease, TSC) is an autosomal dominant disorder characterized by seizures, mental retardation and hamartomatous tumours in multiple organs, including subependymal giant cell astrocytomas, cardiac rhabdomyomas and renal angiomyolipomas. Recent population-based studies suggest a prevalence of 1 case per 25,000 individuals. Renal angiomyolipomas, which may be found sporadically or associated with TSC, become evident as an acute retroperitoneal haemorrhage or by symptoms of a flank mass. Ultrasound and computed tomography provide clear evidence of lipomatous formation while, in rare instances, angiography can demonstrate the existence of multiple vascular tumour compartments. In view of two cases which were admitted with the clinical picture of an acute abdomen on the basis of retroperitoneal haemorrhage, the therapeutic strategies for TSC patients with renal angiomyolipomas are discussed, paying regard to the literature in this field.

Mutation in TSC2 and activation of mammalian target of rapamycin signalling pathway in renal angiomyolipoma

Mutations that inactivate either TSC1 or TSC2 cause tuberous sclerosis. We have used immunoblotting and immunohistochemical analysis to see whether there is phosphorylation of p70 S6 kinase, and the ribosomal S6 protein in angiomyolipomas occurring in tuberous scierosis. Hamartin (encoded by TSC1) and S6K was expressed in all samples. Tuberin (TSC2) was weak or absent in angiomyolipomas, but present in healthy kidney, whereas, phosphorylated p70 S6 kinase and p56 were present only in angiomyolipomas. Our results indicate activation of a mammalian target of rapamycin metabolic pathway in tuberous sclerosis lesions, which contributes to their growth. We suggest that treatment with rapamycin and its analogues could benefit such patients.

Renal angiomyolipomas from patients with sporadic lymphangiomyomatosis contain both neoplastic and non-neoplastic vascular structures

Renal angiomyolipomas are highly vascular tumors that occur sporadically, in women with pulmonary lymphangiomyomatosis (LAM), and in tuberous sclerosis complex (TSC). The goal of this study was to determine whether the distinctive vessels of angiomyolipomas are neoplastic or reactive. We studied angiomyolipomas with loss of heterozygosity (LOH) in the TSC2 region of chromosome 16p13 from patients with LAM. We found that angiomyolipomas contain five morphologically distinct vessel types: cellular, collagenous, hemangiopericytic, glomeruloid, and aneurysmatic. Using laser capture microdissection, we determined that four of the vessel types have TSC2 LOH and are therefore neoplastic. One vessel type, collagenous vessels, did not have LOH, and is presumably reactive. Recently, activation of S6 Kinase and its target S6 ribosomal protein (S6) was demonstrated in cells lacking TSC2 expression. We found that angiomyolipoma vessel types in which LOH were detected were immunoreactive with anti-phospho-S6 antibodies. Angiomyolipoma cells without LOH, including the endothelial component of the vessels, were not immunoreactive. To our knowledge, angiomyolipomas are the first benign vascular tumor in which the vascular cells, rather than the stromal cells, have been found to be neoplastic. Angiomyolipomas appear to reflect novel vascular mechanisms that may be the result of activation of cellular pathways involving S6 Kinase.

Association between a high-expressing interferon-gamma allele and a lower frequency of kidney angiomyolipomas in TSC2 patients

Tuberous sclerosis complex (TSC) is a familial hamartoma syndrome in which renal involvement is common and, at times, life threatening. We have investigated the potential effect of a non-TSC gene on renal disease in a cohort of 172 TSC patients with TSC2 mutations. Patients were genotyped for an interferon-gamma (IFN-gamma) microsatellite polymorphism, within intron 1, for which one common allele (allele 2, with 12 CA repeats) has been shown to have a higher expression of IFN-gamma. A chi(2) analysis was used to examine the association between IFN-gamma allele 2 and the development of kidney angiomyolipomas (KAMLs) in this TSC2 cohort. Because of the age-dependent development of KAMLs in TSC, we initially focused on the 127 patients who were >5 years old. Additional subgroup analyses were done to investigate the influence of age and gender. The transmission/disequilibrium test (TDT) was also performed in a subset of this cohort (46 probands) for whom parent and/or sibling samples were available for analysis. Both chi(2) analysis and TDT suggested an association between IFN-gamma allele 2 and the absence of KAMLs in patients who have known TSC2 mutations. Among the 127 patients who were >5 years old, KAMLs were present in 95 (75%) and were absent in 32 (25%). In the group with KAML present, the frequency of IFN-gamma allele 2 was 56%; in the group with KAML absent, the frequency of IFN-gamma allele 2 was significantly higher, at 78% (P=.02, by chi(2) analysis). The family-based TDT analysis gave similar results, with a TDT statistic (TDT chi2=5.45) corresponding to a P value of.02. Subgroup analyses show that both age and gender may influence the impact of this association. Although these results should be replicated in other populations with TSC, the present study suggests that modifier genes play a role in the variable expression of TSC and also suggests a potential therapy for KAMLs in patients with TSC.

Contemporary diagnosis and management of renal angiomyolipoma

PURPOSE

We present a comprehensive resource that summarizes contemporary advances relevant to the clinical management of renal angiomyolipoma.

MATERIALS AND METHODS

A MEDLINE search was done using the key words angiomyolipoma, hemangioma or lipoma and kidney neoplasm, and therapeutic embolization. References from these articles were reviewed to identify additional relevant source material. We identified 13 series published since 1986 comprising 336 patients as well as 24 reports of therapeutic embolization for angiomyolipoma, comprising 76 patients. To our knowledge we report the largest compilation series to date.

RESULTS

Angiomyolipoma is generally benign, although an uncommon subtype (epithelioid angiomyolipoma) may behave more aggressively. Tuberous sclerosis associated angiomyolipoma tends to be larger, multiple and more likely to cause spontaneous hemorrhage than the sporadic entity. Tumors that hemorrhage tend to be larger. Computerized tomography or magnetic resonance is usually sufficient for diagnosis. Biopsy is rarely useful. Primary indications for intervention include symptoms such as pain or bleeding or suspicion of malignancy. Prophylactic intervention is justifiable for large tumors, in females of childbearing age or in patients in whom followup or access to emergency care may be inadequate. Recent advances that have affected management include improved understanding of tuberous sclerosis complex and angiomyolipoma genetics, the identification of molecular markers that facilitate histopathological diagnosis, and the refinement of embolization and partial nephrectomy techniques.

CONCLUSIONS

Although some cases of angiomyolipoma may require complete nephrectomy, most can be managed by conservative nephron sparing approaches. Ongoing research into the molecular biology and clinical behavior of angiomyolipoma may improve our ability to manage these lesions.

Multiple angiomyolipomata of the liver: a case report

Angiomyolipoma (AML) is a rare benign tumor that occurs most commonly in the kidney. Occasionally it may be found in the liver. Lesions in the liver are usually solitary. Multiple AMLs are extremely rare and are typically seen in patients with tuberous sclerosis. We now report an unusual case of a 46-year-old woman with multiple hepatic AMLs. There were more than 15 lesions distributed predominantly in the right hepatic lobe. The tumors ranged from 0.2 to 6 cm in size and consisted of a variable admixture of proliferating blood vessels, adipose tissue, and smooth muscle. There was no clinical evidence of tuberous sclerosis in this patient. Polymerase chain reaction amplification of the highly polymorphic human androgen receptor gene (HUMARA) was performed and the pattern of X chromosome inactivation was analyzed. Three of the five representative AML nodules showed a preferential loss of one of the two HUMARA alleles indicating a clonal proliferation with involvement of different alleles. Histologic examination of the corresponding lesions showed clonal lesions to be predominantly composed of epithelioid myoid cells while the polyclonal lesions were predominantly composed of adipose tissue. While the histologic diagnosis of AML in a surgical resection specimen is often straightforward, the radiographic, cytologic and intra-operative interpretation of a case with multiple lesions presents a considerable challenge.

Renal disease in adults with TSC2/PKD1 contiguous gene syndrome

The most common renal lesions of tuberous sclerosis complex, an autosomal-dominant syndrome resulting from losses of TSC1 (9q34) or TSC2 (16p13.3), are renal cysts and angiomyolipomas. Epithelial neoplasms are less common. The TSC2 gene lies adjacent to PKD1, the major gene responsible for autosomal-dominant polycystic kidney disease. Recently, a deletion mutation disrupting both TSC2 and PKD1 has been described in young children with tuberous sclerosis complex with severe renal cystic disease. This disease has been termed the TSC2/PKD1 contiguous gene syndrome. We describe the lesions in the resected kidneys of two adults with TSC2/PDK1 contiguous gene syndrome, at the time of the nephrectomies: a 31-year-old man and his 44-year-old mother. The four kidneys were enlarged reniform masses composed of cysts lined by flattened, cuboidal, or, infrequently, large deeply eosinophilic epithelial cells. The kidneys also contained numerous classic angiomyolipomas and rare intraglomerular microlesions. In the son the largest tumor was a monotypic epithelioid angiomyolipoma. In the wall of his left renal pelvis there was a plaque-shaped, HMB-45-positive localized lesion of lymphangioleiomyomatosis. This is the first description of the renal lesions in adults with genetically confirmed TSC2/PDK1 contiguous gene syndrome. The pathologic findings highlight the importance of thorough sampling for histology in polycystic kidney diseases and indicate that the observation of an angiomyolipoma in biopsy material from patients with enlarged cystic kidneys should suggest the diagnosis of TSC2/PKD1 contiguous gene syndrome, even in cases without ultrasonographic and macroscopic evidence of angiomyolipoma.

Molecular genetic evidence for different clonal origin of components of human renal angiomyolipomas

Renal angiomyolipoma is a benign neoplasm composed of variable proportions of blood vessels, smooth muscle, and adipose tissue. Smooth muscle, adipose tissue, blood vessels, and adjacent normal kidney tissue were separately microdissected from sections prepared from formalin-fixed, paraffin-processed tissues from angiomyolipomas from 18 women. X chromosome inactivation analysis using the methylation pattern at exon 1 of the human androgen receptor gene on chromosome Xq11-12 was used to study the clonal origin of each component. Nonrandom inactivation of X chromosomes was found in six of the 15 informative tumors. The smooth muscle and adipose tissue showed differing patterns of nonrandom inactivation of X chromosomes in five angiomyolipomas and the same pattern of nonrandom inactivation of X chromosomes in one. Samples from the blood vessels showed random inactivation of X chromosomes in all informative cases. Our data showed that the adipose tissue and smooth muscle cells of renal angiomyolipoma are both monoclonal but may arise independently. The coexistence of tumor subclones with morphologic heterogeneity can lead to the formation of a clinically detectable tumor.

Concurrent angiomyolipomas and renal cell carcinoma harboring metastatic foci of mammary carcinoma in the same kidney: an incidental autopsy finding in a patient with a follow-up of thirty years

The synchronous occurrence of three different types of renal tumor in a patient is rare. We report a case of conventional (clear cell) renal cell carcinoma harboring metastatic foci of mammary carcinoma associated with two angiomyolipomas in the left kidney incidentally discovered at the autopsy. The patient was a 75-year-old woman, without the tuberous sclerosis complex, who had undergone left radical mastectomy and radiotherapy for an infiltrating duct carcinoma of breast 30 years before. This tumor was widely disseminated at autopsy, but the nontumorous renal parenchyma was free of metastases. To the best of our knowledge this combination of neoplasms has not been described before. This case shows the important role played by autopsy in the accurate investigation of interrelations among coexisting tumors.

The generation and characterization of a cell line derived from a sporadic renal angiomyolipoma: use of telomerase to obtain stable populations of cells from benign neoplasms

Angiomyolipomas are benign tumors of the kidney derived from putative perivascular epithelioid cells, that may undergo differentiation into cells with features of melanocytes, smooth muscle, and fat. To gain further insight into angiomyolipomas, we have generated the first human angiomyolipoma cell line by sequential introduction of SV40 large T antigen and human telomerase into human angiomyolipoma cells. These cells show phenotypic characteristics of angiomyolipomas, namely differentiation markers of smooth muscle (smooth muscle actin), adipose tissue (peroxisome proliferator-activator receptor gamma, PPARgamma), and melanocytes (microophthalmia, MITF), thus demonstrating that a single cell type can exhibit all of these phenotypes. These cells should serve as a valuable tool to elucidate signal transduction pathways underlying renal angiomyolipomas.

Detection of prostate-specific membrane antigen expressing cells in blood obtained from renal cancer patients: a potential biomarker of vascular invasion

Originally, prostate-specific membrane antigen (PSMA) was described in benign and malignant prostate cells. On the basis of recent reports that this antigen also is expressed in normal renal proximal tubular cells and in the neovascular endothelium associated with renal carcinoma, we used a nested reverse transcriptase-polymerase chain reaction assay to evaluate whether PSMA-expressing cells might be present in specimens of peripheral blood obtained from renal cancer patients, benign renal tumor patients, and healthy volunteers. Our reverse transcriptase-polymerase chain reaction PSMA assay had a sensitivity of detecting 1 lymph node prostate cancer (LNCaP) per 10(7) lymphocytes. None of the 20 non-renal cancer controls were positive for PSMA mRNA, whereas 11 of 50 patients (22%) with diagnosed renal cancer were positive. Despite a comparative increase of PSMA positivity with stage, no statistical correlation was found. However, 44% of PSMA-positive patients had tumor size greater than 12 cm, versus only 9% in patients negative for PSMA (P = .03), and 67% of positive PSMA patients were found to have vascular invasion versus only 16% of patients negative for PSMA (P = .006; odds ratio, 10.8). This preliminary study suggests the possibility that PSMA expression in peripheral blood might be a useful biomarker for detecting or monitoring the progression of renal cancer in patients.

Immunohistochemical and reverse transcription-polymerase chain reaction expression analysis of tyrosinase and microphthalmia-associated transcription factor in angiomyolipomas

Angiomyolipomas (AMLs) show a characteristic immunoreactivity with melanocyte differentiation markers such as monoclonal antibody (mAb) HMB45, which detects melanocyte differentiation antigen gp100 and mAb A103 reacting with Melan-A/MART-1. Monoclonal antibody T311 to tyrosinase (a key enzyme of melanogenesis) and mAb D5 to the microphthalmia (Mitf) antigen are two newly available markers of melanocytic differentiation. The authors tested 15 AMLs with T311 and D5 by immunohistochemistry and a subset of 3 cases by reverse transcription-polymerase chain reaction for their expression of tyrosinase and Mitf mRNA. T311 showed poor sensitivity in AMLs because only focal staining was seen in 1 out of 15 cases, although tyrosinase mRNA was found in all tested cases. Mitf mRNA was present in 3 of 3 tested cases, and D5 was positive in 15 of 15 AMLs. However, D5 immunostaining often was focal and not as homogeneous as A103, which was analyzed in a previous study. D5 staining also could be seen in other cell types such as normal renal tubular cells, macrophages, and renal cell carcinoma. The current results show that in contrast with HMB45 and A103, T311 has little or no value in the diagnosis of AMLs. D5 may be useful in a panel of antibodies in the diagnosis of AMLs.

Angiomyxolipoma shares cytogenetic changes with lipoma, spindle cell/pleomorphic lipoma and myxoma

Angiomyxolipoma is a rare variant of lipoma, two cases of which have recently been described. We report on the hitherto unreported clonal chromosomal changes of a third case of angiomyxolipoma. The karyotype showed a 46,XX,t(7;13)(p15;q14),t(8;12)(q13;p13)[17]/46,XX[3]. The involvement of 13q14, 12p13, and 8q13 supports a relationship with other types of benign lipomatous and myxoid tumors.