Clear cell renal cell carcinoma with BAP1 mutation: a report of two cases.

Clear cell renal cell carcinoma is the most common subtype of renal cell carcinomas (RCCs) and accounts for 60%-70% of all RCCs cases in adults. Aberrations in the von Hippel-Lindau (VHL) gene on chromosome 3p occurred in > 90% of clear cell RCCs. Other tumor suppressor genes located on chromosome 3p, such as BAP1, PBRM1, and SETD2, also contribute to tumorigenesis. Clear cell RCCs with both BAP1 and VHL mutations may display distinctive histopathological features. Here, we report two cases of clear cell RCCs with BAP1 mutation. One tumor had VHL, BAP-1, and RAF1 mutations and the tumor nests and alveoli of tumor cells were surrounded by proliferative vessels and the optically clear cytoplasm contained numerous eosinophilic granules and hyaline globules of varying sizes. The other tumor had BAP1 and ATM mutations, and demonstrated clear cells with numerous eosinophilic granules and other typical histopathological features of conventional clear cell RCC. Furthermore, many tumor nodules with dense peripheral lymphocytic infiltrates contained rhabdoid cells. Sarcomatoid cells were also observed. Both tumor cells showed high-grade nuclei. Clear cell RCCs with BAP1 mutation exhibit aggressive clinical behaviors.

Genetic analysis identifies putative tumor suppressor sites at 2q35-q36.1 and 2q36.3-q37.1 involved in cervical cancer progression.

We performed comparative genomic hybridization (CGH) and high-resolution deletion mapping of the long arm of chromosome 2 (2q) in invasive cervical carcinoma (CC). The CGH analyses on 52 CCs identified genetic losses at 2q33-q36, gain of 3q26-q29, and frequent chromosomal amplifications. Characterization of 2q deletions by loss of heterozygosity (LOH) in 60 primary tumors identified two sites of minimal deleted regions at 2q35-q36.1 and 2q36.3-q37.1. To delineate the stage at which these genetic alterations occur in CC progression, we analysed 33 cervical intraepithelial neoplasia (CIN) for LOH. We found that 89% of high-grade (CINII and CINIII) and 40% of low-grade (CINI) CINs exhibited LOH at 2q. To identify the target tumor suppressor gene (TSG), we performed an extensive genetic and epigenetic analyses of a number of candidate genes mapped to the deleted regions. We did not find inactivating mutations in CASP10, BARD1, XRCC5, or PPP1R7 genes mapped to the deleted regions. However, we did find evidence of downregulated gene expression in CFLAR, CASP10 and PPP1R7 in CC cell lines. We also found reactivated gene expression in CC cell lines in vitro after exposure to demethylating and histone deacetylase (HDAC) inhibiting agents. Thus, these data identify frequent chromosomal amplifications in CC, and sites of TSGs at 2q35-q36.1 and 2q36.3-q37.1 that are critical in CC development.

Recurrent nested stromal epithelial tumor of the liver with extrahepatic metastasis: case report and review of literature.

Nested stromal epithelial tumor is a recently described primary neoplasm of the liver. This tumor is characterized by well-demarcated nests of spindle and epithelioid cells with occasional calcification and bone formation. An association between these tumors and Cushing syndrome has been described. Herein we report a case of a recurrent nested stromal epithelial tumor of the liver in a 17-year-old female with aggressive clinical behavior and an extrahepatic lymph node metastasis. Also, we provide the first detailed clinical, histologic, immunohistochemical, and cytogenetic comparison of the original and recurrent tumors. Initially, the patient presented with Cushingoid symptoms and epigastric pain, radiating to her back. A computed tomographic (CT) scan revealed a large lesion in the liver. After a partial hepatectomy, the Cushingoid features were resolved. A year later, a CT scan revealed multiple lesions within the liver, and positron emission tomographic/CT imaging showed a hypermetabolic lymph node. The patient underwent a cadaveric liver transplant. Histologically, both the original and recurrent tumors had similar characteristics, with different immunoreactivity, correlating with the absence of systemic hormonal symptoms. Electron microscopy of the original neoplasm revealed an abundance of rough cytoplasmic reticulum and mitochondria. No evidence of endocrine differentiation was found. Cytogenetics of the primary tumor was complex with an abnormal hypotriploid karyotype. Our data indicate that patients with nested stromal epithelial tumor of the liver must be carefully followed with imaging to detect hepatic recurrence and extrahepatic metastases.

Cloning of an Alpha-TFEB fusion in renal tumors harboring the t(6;11)(p21;q13) chromosome translocation.

MITF, TFE3, TFEB, and TFEC comprise a transcription factor family (MiT) that regulates key developmental pathways in several cell lineages. Like MYC, MiT members are basic helix-loop-helix-leucine zipper transcription factors. MiT members share virtually perfect homology in their DNA binding domains and bind a common DNA motif. Translocations of TFE3 occur in specific subsets of human renal cell carcinomas and in alveolar soft part sarcomas. Although multiple translocation partners are fused to TFE3, each translocation product retains TFE3's basic helix-loop-helix leucine zipper. We have identified the genes fused by the chromosomal translocation t(6;11)(p21.1;q13), characteristic of another subset of renal neoplasms. In two primary tumors we found that Alpha, an intronless gene, rearranges with the first intron of TFEB, just upstream of TFEB's initiation ATG, preserving the entire TFEB coding sequence. Fluorescence in situ hybridization confirmed the involvement of both TFEB and Alpha in this translocation. Although the Alpha promoter drives expression of this fusion gene, the Alpha gene does not contribute to the ORF. Whereas TFE3 is typically fused to partner proteins in subsets of renal tumors, we found that wild-type, unfused TFE3 stimulates clonogenic growth in a cell-based assay, suggesting that dysregulated expression, rather than altered function of TFEB or TFE3 fusions, may confer neoplastic properties, a mechanism reminiscent of MYC activation by promoter substitution in Burkitt's lymphoma. Alpha-TFEB is thus identified as a fusion gene in a subset of pediatric renal neoplasms.