TFE3 expression in tumors of the microphthalmia-associated transcription factor (MiTF) family

Application of TFE3 Immunophenotypic and TFE3 mRNA Expressions in Diagnosis and Prognostication of Adrenal Cortical Neoplasms and Distinction From Kidney Tumors

We explored the application of TFE3 immunostaining and TFE3 mRNA expression in the differential diagnosis and prognostication of adrenal cortical tumors and distinction of the latter from clear cell renal cell carcinoma (ccRCC) which show significant morphologic overlap. TFE3 immunostaining was performed on a large cohort of samples including 40 adrenal cortex tissues, 95 adrenocortical adenoma (ACA), 11 adrenocortical carcinoma (ACC), 53 ccRCC, and 18 pheochromocytomas. TFE3 was compared with other immunomarkers melan-A, inhibin-α, synaptophysin, chromogranin A, CAIX and CD10. One hundred percent normal adrenal cortices and 94% ACA were strongly and diffusely stained for TFE3 while no ACC showed diffuse staining. TFE3 is thus useful in distinguishing ACA from ACC. TFE3 is also useful in separating ACC from ccRCC as 64% ACC showed partial, while only 7% of ccRCC showed partial TFE3 staining. Only 1 pheochromocytoma showed focal weak TFE3 staining. Results also demonstrated superiority of TFE3 over other commonly used immunomarkers. TFE3 gene rearrangement testing by fluorescence in situ hybridization showed no rearrangement in 6 TFE3 positive adrenal tumors. TFE3 mRNA were analyzed by the Cancer Genome Atlas database and we found TFE3 mRNA expression correlated with overall patient survival in ACC. Our study showed usefulness of TFE3 in distinguishing ACA from ACC, and ACC from ccRCC. TFE3 is superior over other commonly used immunomarkers for adrenal tumors. In addition, decreased TFE3 immunoexpression and TFE3 mRNA expression may carry poor prognostic implication in adrenal tumors.

TFE3 Rearrangement and Expression in Renal Cell Carcinoma

TFE3 rearranged Renal cell carcinoma (RCC) is not very common, and demonstrates unique heterogenous morphological features overlapping other recognized entities and distinct immunoprofile. It can be seen in any age group, therefore practicing pathologists should be aware of the distinctive clinical settings and histologic findings associated with these tumors and subsequently employ an adequate panel of ancillary studies in order to confirm the diagnosis. Recognizing these entities remains crucial for future clinical trials and development of novel therapies.

Chameleon TFE3-translocation RCC and How Gene Partners Can Change Morphology: Accurate Diagnosis Using Contemporary Modalities

Translocation renal cell carcinoma (tRCC) with TFE3 gene rearrangements has been born as a distinct entity 20 years ago. These relatively rare tumors were notable among other RCC subtypes because of their disproportionally high incidence among children and young adults. Initial reports were focused on describing unifying morphologic criteria and typical clinical presentation. Follow-up studies of ancillary immunohistochemical and hybridization techniques provided additional diagnostic tools allowing recognition of tRCC tumors in practice. However, a growing body of literature also expanded the clinicomorphologic spectrum of tRCCs, to include a significant morphologic overlap with other RCC variants thus blurring the diagnostic clarity of this entity. More recent molecular studies utilizing next-generation sequencing technology accelerated recognition of numerous novel gene partners fusing at different breakpoints with the TFE3 gene. Accumulating data indicates that morphologic and clinical heterogeneity of tRCC could be explained by fusion subtypes, and knowledge of TFE3 partnering genes may be important in predicting tumor behavior. Herein we provided a comprehensive analysis of ∼400 tRCC cases with known TFE3 fusion partners, estimated their relative incidence and summarized clinicomorphologic features associated with most common fusion subtypes. Our data was based on an extensive literature review and had a special focus on comparing immunohistochemistry, fluorescent in situ hybridization and contemporary molecular studies for the accurate diagnosis of tRCC.

Immunohistochemical expression of PAX8, PAX2, and cytokeratin in melanomas

BACKGROUND

Deviations from the classic melanocytic immunophenotype in melanoma can present a diagnostic challenge. PAX8 and PAX2 are common markers for renal or Müllerian differentiation. While most PAX8+ or PAX2+ carcinomas are seldom confused with melanoma, some cases may show a more ambiguous immunophenotype, especially when MiTF family altered renal cell carcinoma (MiTF-RCC) is in the differential diagnosis. Neither PAX8 nor PAX2 expression has been reported in melanoma to date. We aimed to better characterize PAX8, PAX2, and cytokeratin immunoreactivity in a large series of melanomas.

METHODS

Tissue microarrays consisting of 263 melanomas were immunostained for PAX8, PAX2, and cytokeratin and graded by an h-score.

RESULTS

PAX8 expression was seen in 7.9% of melanomas and was significantly associated with spindle cytomorphology. PAX2 was positive in one (0.4%) melanoma. Cytokeratin positivity was seen in three (1.2%) cases and was associated with metastases.

CONCLUSIONS

PAX8 is expressed in a subset of melanomas and may be strong/extensive. As PAX8 positivity does not exclude a diagnosis of melanoma, it should be used in conjunction with other immunohistochemical markers, such as cytokeratin and PAX2, when melanoma, MiTF-RCC, and other PAX8+ tumors are in the differential diagnosis.

TFE3-expressing malignant perivascular epithelioid cell tumor of the mesentery: A case report and review of literature

BACKGROUND

Perivascular epithelioid cell tumor (PEComa) is a rare mesenchymal tumor that exhibits an epithelioid and spindle cell morphology. The tumor is characterized by immunoreactivity for melanocytic and myogenic markers but can be misdiagnosed as more common tumors with similar characteristics, including gastrointestinal stroma tumors or leiomyosarcomas. Recently, a subset of PEComas has been reported to harbor a transcription factor binding to TFE3 fusion. Herein, we report a rare case of TFE3-expressing malignant PEComa arising from the mesentery.

CASE SUMMARY

A 50-year-old woman presented with abdominal discomfort for 3 months. Results of laboratory tests were all within the normal ranges, and the patient had no notable medical history. Magnetic resonance imaging revealed a large tumor on the right side of the pelvic floor, which was originally suspected to be a primary ovarian tumor. However, during surgery, the tumor was revealed to have originated from the mesentery. Histologically, the tumor was composed of bundles of spindle cells and sheets of epithelioid cells. Extensive coagulative necrosis and numerous mitotic figures were observed. Immunohistochemistry revealed that the tumor cells were positive for smooth muscle actin, HMB-45, and TFE3 expression. Tumor involvement of the rectal serosa was identified, leading to a final diagnosis of malignant PEComa of the mesentery. Surgical resection was followed by adjuvant chemotherapy. No recurrence or metastasis was observed over a 6-month follow-up period.

CONCLUSION

Malignant PEComa of the mesentery is extremely rare and should be distinguished from morphological mimics through differential diagnosis and immunohistochemistry.

Clinical features of 18 perivascular epithelioid cell tumor cases

To investigate the biological behavior and clinical characteristics of perivascular epithelioid cell tumor (PEComa).Eighteen PEComa patients admitted to Zhongshan Hospital and the Central Hospital of Xuhui District in China from January 2006 to October 2018 were included. All patients were diagnosed based on pathological findings and treated with surgical resection or medication.Among the 18 patients, 1 underwent lymph node biopsy for multiple enlarged lymph nodes and 17 underwent mass resection. The median disease-free survival was 22 months after the first resection and over 12 months following a second resection. Treatment with mechanistic target of rapamycin (mTOR) inhibitors was effective for patients with unresectable or metastatic lesions. The median progression-free survival was approximately 13 months.Surgery is the predominant treatment approach for PEComa and patients can benefit from multiple operations. mTOR inhibitors are considered for patients with multiple lesions or intolerance to surgery. Anti-angiogenetic drugs can be selected when mTOR inhibitors fail to control the illness.

Gene of the month: TFE 3

Transcription factor enhancer 3 (TFE3), on the short arm of chromosome Xp11.23 and its protein, belongs to the microphthalmia transcription family (MiTF) of transcription factors. It shares close homology with another member of the family, MiTF which is involved in melanocyte development. When a cell is stressed and/or starved, TFE3 protein translocates into the nucleus. TFE3 gene fusions with multiple different partner genes occur in several tumours with resultant nuclear expression of TFE3 protein. The main tumours associated with TFE3 gene fusions are: renal cell carcinoma, alveolar soft part sarcoma, a subset of epithelioid haemangioendotheliomas (EHE), some perivascular epithelioid cell tumours and rare examples of ossifying fibromyxoid tumour and malignant chondroid syringoma. TFE3 immunohistochemistry is of use in routine diagnostic practice with the aforementioned tumours harbouring TFE3 fusions leading to nuclear staining. In addition, there are tumours lacking TFE3 fusions but also display TFE3 nuclear immunolabeling, and these include: granular cell tumour, solid pseudopapillary neoplasm of the pancreas and ovarian sclerosing stromal tumour.

Practical Application of Lineage-Specific Immunohistochemistry Markers: Transcription Factors (Sometimes) Behaving Badly

CONTEXT.—

Transcription factors (TFs) are proteins that regulate gene expression and control RNA transcription from DNA. Lineage-specific TFs have increasingly been used by pathologists to determine tumor lineage, especially in the setting of metastatic tumors of unknown primary, among other uses. With experience gathered from its daily application and increasing pitfalls reported from immunohistochemical studies, these often-touted highly specific TFs are not as reliable as once thought.

OBJECTIVES.—

To summarize the established roles of many of the commonly used TFs in clinical practice and to discuss known and potential sources for error (eg, false-positivity from cross-reactivity, aberrant, and overlap "lineage-specific" expression) in their application and interpretation.

DATA SOURCES.—

Literature review and the authors' personal practice experience were used. Several examples selected from the University Health Network (Toronto, Ontario, Canada) are illustrated.

CONCLUSIONS.—

The application of TF diagnostic immunohistochemistry has enabled pathologists to better assess the lineage/origin of primary and metastatic tumors. However, the awareness of potential pitfalls is essential to avoid misdiagnosis.

Melanotic Xp11-associated tumor of the sigmoid colon: A case report

BACKGROUND

Melanotic Xp11-associated tumors are rare mesenchymal-derived tumors. So far, most primary melanotic Xp11-associated tumors have been reported in the kidney, and reports of this tumor in the gastrointestinal tract are rare.

CASE SUMMARY

Here we describe the case of a 25-year-old woman who presented with a melanotic Xp11-associated tumor in the sigmoid colon. Colonoscopy revealed a large mucosal bulge in the sigmoid colon, approximately 32 cm inside the anus. The surface was rough with local erosion. The tumor was brittle on biopsy and bled easily. Computed tomography revealed thickening of the rectal wall with edema. Postoperative pathology indicated the likelihood of a perivascular epithelioid cell tumor. Histologically, the tumor comprised plump epithelioid cells with abundant clear to lightly eosinophilic cytoplasm and round nuclei arranged in an alveolar or trabecular pattern. The tumor cells were strongly positive for HMB-45, Melan-A, Cathepsin K, and TFE3 but negative for vimentin, smooth muscle actin, S100 protein, CD10, CK20, and desmin. The tumor cells had a low Ki-67 labeling index (approximately 2%). Fluorescence in situ hybridization revealed TFE3 fracture. Based on these histologic and immunohistochemical features, a diagnosis of melanotic Xp11-associated tumor of the sigmoid colon was made.

CONCLUSION

In summary, we report the clinicopathological features of a primary tumor that is extremely rare in the sigmoid colon and review the clinicopathological characteristics of melanotic Xp11-associated tumors, compatible with the very rare tumor termed “melanotic Xp11 translocation renal cancer” in all aspects.

Melanotic MiT family translocation neoplasms: Expanding the clinical and molecular spectrum of this unique entity of tumors

MiT family translocation tumors are a group of neoplasms characterized by translocations involving MiT family transcription factors. The translocation renal cell carcinomas, TFE3 (Xp11.2) and TFEB (t6;11) are known members of this family. Melanotic Xp11 translocation renal cancer is a more recently described entity. To date only 14 cases have been described. It is characterized by a distinct set of features including a nested epithelioid morphology, melanin pigmentation, labeling for markers of melanocytic differentiation, lack of labeling for markers of renal tubular differentiation, predominance in a younger age population and association with aggressive clinical behavior. There are noted similarities between that entity and TFE3 associated PEComas. There are no cases reported of equivalent melanotic TFEB translocation renal cancer. We report 2 rare cases of melanotic translocation renal neoplasms. The first is a melanotic TFE3 translocation renal cancer with an indolent clinical course, occurring in a patient more than 3-decades older than the usual average age in which such tumors have been described. The other case is, to our knowledge, the first reported melanotic TFEB translocation cancer of the kidney. Both cases exhibit the same H&E morphology as previously reported in melanotic translocation renal cancers and label accordingly with HMB45 and Melan-A. While the TFE3 melanotic tumor lacked any evidence of renal tubular differentiation, the TFEB melanotic cancer exhibited some staining for renal tubular markers. Based on the unique features noted above, these two cases expand the clinical and molecular spectrum of the melanotic translocation renal cancers.

Rheb/mTOR/p70s6k Cascade and TFE3 Expression in Conventional and Sclerosing PEComas of the Urinary Tract

Perivascular epithelioid cell tumors (PEComas) are rarely found in the urinary tract. The clinicopathologic characteristics of 10 cases, retrospectively collected from 5 medical institutions in 3 different European countries, are presented in this study. Male/female ratio was 3:7 and the average age at diagnosis was 62.7 years. Nine cases were sporadic and 1 showed germline mutation of the TSC2 gene. Eight cases were located in the kidney, 1 in the left adrenal and 1 in the right ureter. All of the patients were alive and free of disease at the time of last contact (mean follow-up, 14.1 mo). Four cases displayed a conventional morphology and 6 showed a prominent sclerotic stroma. By immunohistochemistry, melanocytic markers were consistently expressed, especially HMB-45 (10 cases), MiTF (9 cases), and Melan-A (6 cases). Desmin was expressed in 6 cases; 2 cases were positive for CD117; a single case showed TFE3 expression. pMAPK, mTOR, and pAKT demonstrated variable immunostaining with focal positivity in 7, 4, and 2 cases, respectively. Cytokeratins were repeatedly negative in all cases. PEComas in the urinary tract, especially in the renal region, may show a relatively high frequency of the sclerosing histologic subtype. Knowledge of the distinct histology and immunohistochemical profile is vital to correctly diagnose this rare entity.

TFE3 regulates renal adenocarcinoma cell proliferation via activation of the mTOR pathway

The present study aimed to investigate the role of transcription factor E3 (TFE3) in the regulation of proliferation in renal adenocarcinoma cells. The LV-TFE3 overexpression (OE) lentivirus and negative control CON195 (NC) lentivirus were transfected into the ACHN cell line. Protein expression of FLAG-tag TFE3 was determined using western blot analysis. Differences in cell proliferation, plate clone formation and cell cycle distribution between OE and NC groups were compared using MTT, plate colony formation and flow cytometry assays, respectively. The levels of mammalian target of rapamycin (mTOR) and phosphorylated ribosomal protein S6 (p-rpS6) were analyzed by western blotting. Cell proliferation and colony formation increased significantly in the OE group compared with the NC group. The % of cells in the G1 and G2 phases of the cell cycle decreased, while the % of cells in the S phase of the cell cycle increased in the OE group compared with the NC group. In addition, mTOR and p-rpS6 levels were increased in the OE group compared with the NC group. The results of the present study demonstrated that TFE3 overexpression resulted in increased ACHN cell proliferation and plate clone formation. TFE3 may promote renal tumor growth by regulating cell cycle progression and activating the phosphatidylinositol 3-kinase/AKT serine/threonine kinase 1/mTOR signaling pathway.

Diagnostically Challenging Epithelioid Soft Tissue Tumors

In this article, we focus on the histologic features, differential diagnosis, and potential pitfalls in the diagnosis of epithelioid sarcoma, alveolar soft part sarcoma, clear-cell sarcoma, ossifying fibromyxoid tumor, and malignant extrarenal rhabdoid tumor. Numerous other soft tissue tumors also may have epithelioid variants or epithelioid features. Examples include epithelioid angiosarcoma, epithelioid malignant peripheral nerve sheath tumor, epithelioid gastrointestinal stromal tumor, and perivascular epithelioid cell tumor, among others.

PEComa: morphology and genetics of a complex tumor family

Perivascular epithelioid cell tumors, or PEComas, are mesenchymal neoplasms composed of histologically and immunohistochemically distinctive epithelioid or spindle cells, which are immunoreactive for both smooth muscle and melanocytic markers. The cells in PEComas are typically arranged around blood vessels and appear to form the vessel wall, often infiltrating the smooth muscle of small- to medium-sized vessels. Periluminal cells are usually epithelioid and the more peripheral cells are spindle shaped. The cells have small, round to oval nuclei, sometimes with focal nuclear atypia, and clear to eosinophilic cytoplasm, and no counterpart normal cell has been identified. The PEComa "family" now includes angiomyolipoma, pulmonary clear cell "sugar" tumor and lymphangioleiomyomatosis, primary extrapulmonary sugar tumor, clear cell myomelanocytic tumor of the falciform ligament/ligamentum teres, abdominopelvic sarcoma of perivascular epithelioid cells, and other tumors with similar features at various sites that are simply termed PEComa. Some PEComas occur in patients with tuberous sclerosis complex and share the genetic abnormalities. There is a behavioral spectrum from benign to frankly malignant, and histologic criteria have been proposed for assessing malignant potential. The differential diagnosis can include carcinomas, smooth muscle tumors, other clear cell neoplasms, and adipocytic tumors. PEComas constitute a genetically diverse group that includes neoplasms harboring TFE3 gene rearrangements and those with TSC2 mutations, indicating alternative tumorigenic pathways. Recent advances in therapy of malignant PEComas relate to increased knowledge of specific genetic changes and their effects on metabolic pathways that are susceptible to specific interventions. We review PEComas, emphasizing the diagnostic spectrum and recent immunohistochemical and genetic findings.

Perivascular epithelioid cell tumor (PEComa) with TFE3 gene rearrangement: clinicopathological, immunohistochemical, and molecular features

Perivascular epithelioid cell tumors (PEComas) have been increasingly associated with gene rearrangement of the transcription factor E3 (TFE3). We present three cases of PEComa with a TFE3 gene abnormality detected by immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH). Their clinical features, pathological morphology, and prognosis were investigated. Histologically, the tumors in these three cases showed predominantly epithelioid cells arranged in nests or sheets separated by a delicate vascular network, within two of the three cases nuclear atypia, mitotic figures, and necrosis. All three cases showed strong TFE3 and cathepsin K immunoreactivity and weak to strong reactivity for HMB45. One case of PEComa with TFE3 gene fusion exhibited a benign course. The other two cases of PEComa with both TFE3 translocation and X-chromosome polysomy were histologically malignant and showed aggressive growth. In summary, unusual cases of PEComa with TFE3 gene rearrangement might present malignant histological features and aggressive clinical behavior. Our results add cases to the literature and describe an association of polysomy with aggressive behavior.

Unusual myoid, perivascular, and postradiation lesions, with emphasis on atypical vascular lesion, postradiation cutaneous angiosarcoma, myoepithelial tumors, myopericytoma, and perivascular epithelioid cell tumor

In recent years, a number of new soft tissue tumor entities have been described that occur in the skin only, or that also occur in other sites but form clinically and pathologically distinct subsets when arising in the skin and subcutaneous tissue. These include a variety of mesenchymal lineages and have variable malignant potential, although superficial malignant soft tissue tumors generally have a more favorable outcome than their more deeply located counterparts. This article reviews the clinical and pathologic features and differential diagnoses of atypical vascular lesion, postradiation cutaneous angiosarcoma, myoepithelioma, myopericytoma, and perivascular epithelioid cell tumor.

Transcription factor E3 protein-positive perivascular epithelioid cell tumor of the appendix presenting as acute appendicitis: a case report and review of the literature

Perivascular epithelioid cell tumors (PEComas) are a group of mesenchymal tumors that coexpress melanocytic and smooth muscle markers; their exact origin remains unknown. This group includes renal angiomyolipoma, clear cell sugar tumor, and lymphangioleiomyomatosis, although the term perivascular epithelioid cell tumors is currently used for lesions that exhibit a similar morphologic and immunohistochemical profile throughout the human body. Recently, a distinct subset of PEComas has been shown to harbor transcription factor E3 gene (TFE3) fusions. We report, for the first time, a unique case of TFE3-positive PEComa presenting as acute appendicitis in a 24-year-old woman. Microscopically, the tumor was composed of benign-appearing epithelioid cells with clear and eosinophilic cytoplasm, and arranged in nested and alveolar patterns. Immunohistochemical studies showed diffuse strong positivity for neuron-specific enolase, TFE3, and progesterone receptor and focal strong positivity for human melanoma black-45 (HMB-45) and melanocyte differentiation antigen (Melan-A) in the tumor cells. Although rare, PEComa should be included in the differential diagnosis of mesenchymal tumors of the appendix.

Cathepsin K expression in a wide spectrum of perivascular epithelioid cell neoplasms (PEComas): a clinicopathological study emphasizing extrarenal PEComas

AIMS

Recent studies have demonstrated that cathepsin K seems to be a powerful marker in identifying renal perivascular epithelioid cell neoplasms (PEComas). However, the expression in extrarenal PEComas has not been well characterized due to their rare incidence. Our aim was to investigate the expression of cathepsin K in a wide spectrum of extrarenal PEComas and evaluate its potential diagnostic usefulness in comparison with other commonly used markers.

METHODS AND RESULTS

Twenty-three cases of PEComa (liver, n = 9; lung, n = 1; broad ligament of uterus, n = 1; vertex subcutaneous soft tissue, n = 1; abdominal wall, n = 1; and kidney, n = 10) were selected for study. All displayed a high percentage of cells with moderately to strongly positive reactions for cathepsin K (mean 91%; range 80-100%). HMB45, Melan-A and smooth muscle actin (SMA) were expressed in 78, 87 and 87% of cases, respectively, with various percentages of positive cells (mean, 34, 40 and 38%; range 0-80, 0-90 and 0-90%). Transcription factor E3 (TFE3) was expressed strongly in only three cases; none exhibited evidence of TFE3 gene fusion or amplification.

CONCLUSIONS

Cathepsin K appears to be more powerful than other commonly used markers in diagnosing a wide spectrum of PEComas and distinguishing them from the majority of human cancers.

Melanotic xp11.2 neoplasm of the ovary: report of a unique case

We describe a primary ovarian neoplasm, occurring in a 15-year-old female patient, with morphologic, immunohistochemical, and molecular genetic features identical to those of the very rare tumors of the kidney previously described as "melanotic Xp11 translocation renal cancer." This represents, to the best of our knowledge, the first report of a melanotic Xp11 translocation-associated neoplasm arising outside of the kidney. We discuss the relationship of these rare tumors to neoplasms showing perivascular epithelioid cell differentiation, in particular those showing TFE3 rearrangements.