Epithelioid angiomyolipoma of the kidney mimicking renal sarcoma

Two novel TSC2 mutations in renal epithelioid angiomyolipoma sensitive to everolimus

People who suffers renal angiomyolipoma (AML) has a low quality of life. It is widely known that genetic factors including TSC2 mutation contribute to certain populations of renal AML-bearing patients. In this study, we are the first to identify novel TSC2 mutations in one Chinese renal epithelioid AML patient: c.2652C>A; c.2688G>A based on sequencing result from biopsy tissue. These two somatic mutations cause a translational stop of TSC2, which leads to mTORC1 activation. Given the fact that activation of mTORC1 ensures cell growth and survival, we applied its inhibitor, FDA-approved everolimus, to this woman. After months of treatment with everolimus, Computer-Tomography (CT) scan results showed that everolimus successfully reduced tumor growth and distal metastasis and achieved partial response (PR) to everolimu according to Response Evaluation Criteria in Solid Tumors (RECIST version 1.1). Further Blood Routine Examination results showed the concentration of red cell mass, hemoglobin, white blood cell (WBC), platelets and hematocrit (HCT) significantly returned to normal levels indicating patients with these two TSC2 mutations could be effectively treated by everolimus.

A Four-Year Follow-up Study of Renal Epithelioid Angiomyolipoma: A Multi-Center Experience and Literature Review

In this study, we systematically explored the clinical manifestations, diagnosis, treatment, and prognosis of renal epithelioid angiomyolipoma (EAML) retrospectively by analyzing data of 52 patients diagnosed with EAML at four centers. Our results showed that the onset of EAML was usually inconspicuous, and so no obvious symptoms or signs had occurred in most patients at diagnosis. Its diagnoses always depended on postoperative pathological examination. The immunohistochemical (IHC) results [HMB45 ( + ), cytokeratin (-), and S100 (-)] could be used to differentiate EAML from other malignancies such as renal cell cancer (RCC) and sarcomas. For treatment, surgery resulted in satisfactory short-term prognosis. The long-term prognosis of patients with EAML was poor, particularly when a large size, a high percentage of epithelioid component, tumor thrombus formation, and necrosis were present. In conclusion, EAML is a tumor with malignant potential. Once diagnosed, integrated approaches, including surgery, chemotherapy, and targeted therapy, should be considered; a close follow-up regimen is necessary for cases that met: 1) tumor size >9 cm, 2) tumor thrombus formation in the vein, 3) epithelioid cells >70% or atypia cells >60%, and 4) necrosis.

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.

Malignant epithelioid angiomyolipoma of the kidney with pulmonary metastases and p53 gene mutation

Angiomyolipoma (AML) is a rare tumor mainly arising in the kidney. Here we report the case of a 55-year-old woman with malignant epithelioid angiomyolipoma with p53 gene mutation. After 7 years from radical nephrectomy of the left kidney, the patient developed multiple lung metastases that showed morphologic features overlapping those of the previously lesion, which was misdiagnosed as renal cell carcinoma. Both renal and pulmonary tumors were reevaluated by immunohistochemical assay, which were showed positive for HMB-45 and p53 protein (95%), but negative for epithelial markers and S-100 protein. A correct diagnosis of malignant epithelioid angiomyolipoma was made on the basis of those results. Meanwhile exon 8 mutation of p53 gene was detected in the renal tumor by microdissection-PCR-SSCP and sequencing technique indicating that p53 gene mutation may play an important role in malignant transformation. The patient was died of respiratory failure after 15 years’ follow-up. This is the second report of renal malignant angiomyolipoma with p53 gene mutation.

A massive renal epithelioid angiomyolipoma with multiple metastatic lymph nodes

A 47-year-old man presented with dull pain in the left upper abdomen for 1 year. Computed tomograph (CT) examination revealed a very large heterogeneously enhancing mass in the left kidney, measuring up to 28 cm. The mass was accompanied by several enlarged lymph nodes in the peri-aortic region. Radical nephrectomy was performed and pathologic evaluation revealed sheets of epithelioid cells and piecemeal necrosis consistent with malignant epithelioid angiomyolipoma (EAML) with regional lymph node metastases. The tumor cells were strongly positive for human melanosome-associated protein (HMB-45) on immunohistochemical staining. There was neither metastasis nor recurrence 2 years postoperatively. EAML is a rare tumor of mesenchymal tissue with potential for aggressive behavior. If this neoplasm is suspected based on CT features, EAML should be confirmed by pathology and immunohistochemistry.

Renal epithelioid angiomyolipoma: a study of six cases and a meta-analytic study. Development of criteria for screening the entity with prognostic significance

AIMS

Renal epithelioid angiomyolipoma (EAML) is only described in case reports or in multi-institutional small series. The aim was to report cases seen at our institution and to perform a meta-analysis based on a literature review.

METHODS AND RESULTS

Six EAML cases seen at our institution were reviewed and a meta-analysis performed using cases retrieved from a literature review. There were a total of 69 cases for review. The male:female ratio was 1:3. In the absence of areas of typical AML, useful features in distinguishing EAML from epithelial renal neoplasms include: extreme degree of cytological atypia, histiocytoid appearance, presence of melanocytic pigments, solid architecture with the absence of frequent areas of alveolar pattern, tubulo-papillary formation and scarring. A fatal outcome, distant or lymph node metastasis, venous invasion and local recurrence were considered as adverse events and occurred in 40% of cases over a period of follow-up of 3-60 months (mean 22.5 +/- 18 months). Tumours with an unfavourable outcome showing marked cytological atypia and extensive tumour necrosis were larger (135 +/- 43 mm) than those with a favourable outcome (79 +/- 50 mm) (P < 0.002), and predominantly occurred in men.

CONCLUSIONS

Renal neoplasms with certain unusual features should be investigated immunohistochemically to rule out the possibility of EAML. The frequency of adverse outcome is lower in EAML than in renal cell carcinoma.

Renal angiomyolipoma: clinicopathologic study of 194 cases with emphasis on the epithelioid histology and tuberous sclerosis association

The majority of renal angiomyolipoma (AML) is sporadic and occasionally it occurs as part of tuberous sclerosis complex (TSC). Epithelioid AML (EAML), an uncommon variant, is considered potentially malignant based on anecdotal case reports. The prognostic significance of epithelioid component in an otherwise typical AML is uncertain. We studied 194 AMLs for the clinicopathologic features of epithelioid and TSC-associated AMLs. Epithelioid component was present in 15 cases (7.7%) with an average amount of 51% (range: 10% to 100%). Histologically, the epithelioid tumor cells were categorized into small, intermediate, and large cell type based on the cell size. Worrisome histologic features were seen in many EAMLs, including coagulative tumor necrosis in 27% (4/15), nuclear atypia in 93% (14/15), mitosis in 47% (7/15), and atypical mitosis in 1 case. All 15 EAML patients had a mean follow-up time of 5.1 years and none had local recurrence or distant metastasis. Sixteen (8.2%) AMLs occurred in patients with definitive TSC. Three histologic features, namely microscopic AML foci, epithelioid component, and epithelial cysts, were present in 10 (62.5%), 4 (25%), and 44% (7/16), respectively, of TSC-associated AMLs, compared with 11 (6.2%), 11 (6.2%), and 6 (3.4%), respectively, in non-TSC-associated AMLs (P value all <0.01). In summary, all 15 cases of EAMLs in our study had benign clinical outcomes despite adverse pathologic features. Epithelioid component, epithelial cysts, and microscopic AML foci are strongly associated with TSC and the presence of all 3 features should raise strong suspicion for TSC.

Malignant epithelioid angiomyolipoma of the kidney in a patient with tuberous sclerosis: an autopsy case report with p53 gene mutation analysis

We report an autopsy case of malignant epithelioid angiomyolipoma in a 36-year-old male tuberous sclerosis patient. He had been diagnosed to have a bilateral renal tumor 20 years previously. The left kidney had been surgically resected at the age of 34, and the left renal tumor was pathologically diagnosed as classic angiomyolipoma and epithelioid angiomyolipoma. He suddenly died of cardiac arrest, and at autopsy the right kidney weighed 7120 g. The tumor presented with massive necrosis invading the inferior vena cava, but was not hemorrhagic. Microscopic examination revealed tumor cells varying in size with a predominantly solid proliferation pattern and marked atypical large cells with vesicular nuclei and abundant eosinophilic cytoplasm. Mitotic figures were often encountered, and atypical forms were also present. Metastatic lesions were identified in the right lung, liver, diaphragm, and mesentery. Immunohistochemical examination showed epithelioid angiomyolipoma cells that were focally reactive for HMB-45 and showed diffuse positive staining for Melan-A. No mutation was detected in the p53 gene by polymerase chain reaction-single-strand conformation polymorphism (PCR-SSCP) analysis despite diffuse immunoreactivity for p53. This case was proven to be malignant because of the occurrence of distant metastases, and showed that p53 mutations are not always associated with malignant transformation in epithelioid angiomyolipoma.

Malignant Epithelioid Angiomyolipoma of the Kidney

Angiomyolipoma (AML) is a common benign renal tumor composed of thick-walled blood vessels, smooth muscle, and adipose tissue, but the malignant epithelioid variant is extremely rare. A 78-year-old woman presented with fever and left flank pain for 3 days. Computed tomography showed a heterogeneously enhanced mass without fat density in the left kidney. Radical nephrectomy was performed and pathology showed malignant epithelioid AML with regional lymph node metastases. The tumor cells were positive for human melanosome-associated protein (HMB-45) on immunohistochemical staining. The patient died of disseminated metastases (lungs and bones) 5 months postoperatively. Epithelioid AML is a potentially aggressive tumor. The prognosis is poor in metastatic disease. HMB-45 immunoreactivity is a useful marker to make diagnosis.