Perivascular epithelioid cell tumors (PEComas) harboring TFE3 gene rearrangements lack the TSC2 alterations characteristic of conventional PEComas: further evidence for a biological distinction.

*Brigham & Women's Hospital Boston, MA †Department of Pathology, Emory University, Atlanta, GA ‡Department of Pathology, University of Verona, Verona, Italy §The Johns Hopkins Hospital Baltimore, MD.
The American journal of surgical pathology (Impact Factor: 4.59). 03/2012; 36(5):783-4. DOI: 10.1097/PAS.0b013e31824a8a37
Source: PubMed
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    ABSTRACT: In this study, we reported the first PEComa arising within the cervix with TFE3 gene rearrangement and aggressive biological behavior. Morphologically, the tumor showed infiltrative growth into the surrounding parenchyma. The majority of tumor cells were arrayed in sheets, alveolar structures, or nests separated by delicate fibrovascular septa. There was marked intratumoral hemorrhage, necrosis, and stromal calcifications. The tumor cells had abundant clear cytoplasm, focally containing finely granular dark brown pigment, morphologically considered to be melanin. Immunohistochemically, the tumor cells demonstrated moderately (2+) or strongly (3+) positive staining for TFE3, HMB45, and Melan A but negative for CKpan, SMA, S100, PAX8, and PAX2. The presence of Ki-67 protein demonstrated a moderate proliferation rate, with a few Ki-67-positive nuclei. Using a recently developed TFE3 split FISH assay, the presence of TFE3 rearrangement was demonstrated. All these clinicopathologic features are suggestive of TFE3-rearranged PEComas of the cervix. Our results both expand the known characteristics of primary cervix PEComas and add to the data regarding TFE3 rearrangement-associated PEComas.
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    ABSTRACT: 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.
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    ABSTRACT: Tuberous Sclerosis Complex (TSC) is a genetic disorder characterized by seizures and tumor formation in multiple organs, mainly in the brain, skin, kidney, lung and heart. Renal Cell Carcinoma (RCC) occurs in about 3% of TSC patients, and typically develops at age<50. Here we describe genetic findings in two TSC patients with multiple renal tumors, each of whom had the germline mutation TSC2 p.R905Q. The first (female) TSC patient had a left followed by a right nephrectomy at ages 24 and 27. Both kidneys showed multifocal TSC-associated papillary RCC (PRCC). Targeted, next-generation sequencing (NGS) analysis of TSC2 in five tumors (4 from the left kidney, 1 from the right) showed LOH in one tumor, and four different TSC2 point mutations (p.E1351*, p.R1032*, p.R1713H, c.4178_4179delCT) in the other four samples. Only one of the 11 other tumors available from this patient had one of the TSC2 second hit mutations identified. Whole exome analysis of the five tumors identified a very small number of additional mutated genes, with an average of 3.4 nonsilent coding, somatic mutations per tumor, none of which were seen in>1 tumor. The second (male) TSC patient had bilateral partial nephrectomies (both at age 36), with similar findings of multifocal PRCC. NGS analysis of TSC2 in two of these tumors identified a second hit mutation c.2355+1G>T in one sample that was not seen in other tumors. In conclusion, we report the first detailed genetic analysis of RCCs in TSC patients. Molecular studies indicate that tumors developed independently due to various second hit events, suggesting that these patients experienced a 'shower' of second hit mutations in TSC2 during kidney development leading to this severe phenotype. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email:
    Human Molecular Genetics 11/2014; · 6.68 Impact Factor

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