Melamed, Jonathan

Transcription factor E3-rearranged renal cell carcinoma (TFE3-RCC) has heterogenous morphologic and immunohistochemical (IHC) features. 131 pathologists with genitourinary expertise were invited in an online survey containing 23 questions assessing their experience on TFE3-RCC diagnostic work-up. Fifty (38%) participants completed the survey. 46 of 50 participants reported multiple patterns, most commonly papillary pattern (almost always 9/46, 19.5%; frequently 29/46, 63%). Large epithelioid cells with abundant cytoplasm were the most encountered cytologic feature, with either clear (almost always 10/50, 20%; frequently 34/50, 68%) or eosinophilic (almost always 4/49, 8%; frequently 28/49, 57%) cytology. Strong (3+) or diffuse (>75% of tumour cells) nuclear TFE3 IHC expression was considered diagnostic by 13/46 (28%) and 12/47 (26%) participants, respectively. Main TFE3 IHC issues were the low specificity (16/42, 38%), unreliable staining performance (15/42, 36%) and background staining (12/42, 29%). Most preferred IHC assays other than TFE3, cathepsin K and pancytokeratin were melan A (44/50, 88%), HMB45 (43/50, 86%), carbonic anhydrase IX (41/50, 82%) and CK7 (32/50, 64%). Cut-off for positive TFE3 fluorescent in situ hybridisation (FISH) was preferably 10% (9/50, 18%), although significant variation in cut-off values was present. 23/48 (48%) participants required TFE3 FISH testing to confirm TFE3-RCC regardless of the histomorphologic and IHC assessment. 28/50 (56%) participants would request additional molecular studies other than FISH assay in selected cases, whereas 3/50 participants use additional molecular cases in all cases when TFE3-RCC is in the differential. Optimal diagnostic approach on TFE3-RCC is impacted by IHC and/or FISH assay preferences as well as their conflicting interpretation methods.

Abstract Objectives To describe the histologic features that are helpful in the diagnosis of the rare bronchiolar adenomas/ciliated muconodular papillary tumors (BAs/CMPTs) during intraoperative consultation. Methods Multi-institutional retrospective review of frozen sections of 18 BAs/CMPTs. Results In 14 of 18 cases, BA/CMPT was the primary reason for sublobar lung resection, and in 4 cases, BA/CMPT was an incidental finding intraoperatively for resections performed for carcinoma in other lobes. There were 11 proximal-type/classic BAs/CMPTs and 7 distal-type/nonclassic BAs/CMPTs. Only 3 (16.7%) of 18 were correctly diagnosed at the time of frozen section, all of which were proximal type/classic. The remainder were diagnosed as adenocarcinoma (n = 7); invasive mucinous adenocarcinoma (n = 1); non–small cell lung carcinoma (n = 1); cystic mucinous neoplasm, favor adenocarcinoma (either mucinous or colloid type) (n = 1); favor adenocarcinoma, cannot exclude CMPT (n = 1); atypical proliferation (n = 2); mucinous epithelial proliferation (n = 1); and mucous gland adenoma (n = 1). Conclusions BA/CMPT can potentially be misdiagnosed as carcinoma during intraoperative consultation. On retrospective review of the frozen sections, the presence of the following may help to avoid misdiagnosis: a mixture of bland ciliated columnar cells, mucinous cells, and, most important, a basal cell layer, as well as a lack of necrosis, significant atypia, and mitoses.

Abstract Aberrant activation of the androgen receptor (AR) by the ErbB2/ErbB3 heterodimer contributes to the development of hormone resistance in prostate cancer. EBP1, an ErbB3-binding protein, acts as an AR corepressor. As EBP1 is decreased in preclinical models of hormone-refractory prostate cancer, we studied the expression of EBP1 in human prostate cancer. We found that the expression of the EBP1 gene was significantly decreased in prostate cancer tissues compared with benign prostate at both mRNA and protein levels. Restoration of EBP1 expression in the hormone-refractory LNCaP C81 cell line led to an amelioration of the androgen-independent phenotype based on established biological criteria and a reduction in the expression of a cohort of AR target genes. The ability of the ErbB3 ligand heregulin (HRG) to stimulate growth and AKT phosphorylation of hormone-refractory prostate cancer cells was abolished. Abrogation of EBP1 expression by short hairpin RNA in hormone-dependent LNCaP cells, which undergo apoptosis in response to HRG, resulted in HRG-stimulated cell growth. Restoration of EBP1 expression decreased the tumorigenicity of C81 xenografts in female mice, whereas elimination of EBP1 expression enhanced the ability of LNCaP cells to grow in female mice. Our data support a role for EBP1 in the development of hormone-refractory prostate cancer via inhibition of both AR- and HRG-stimulated growth and present a novel strategy for treating androgen-refractory prostate cancer. [Mol Cancer Ther 2008;7(10):3176–86]