Search

Poorly differentiated sinonasal carcinomas are a heterogenous group of aggressive neoplasms that encompasses squamous cell carcinoma including basaloid variant, lymphoepithelial carcinoma, sinonasal undifferentiated carcinoma, and neuroendocrine-type small cell carcinoma. We herein describe 3 cases of a hitherto unreported variant combining features of basaloid carcinoma with variable intermingled rhabdoid cells. Patients were 2 women (aged 28 and 35) and a man (52 y) who presented with sinonasal masses. All had advanced local disease with bone involvement (pT4). None had a history of irradiation or a family history of rhabdoid tumors. Treatment was surgery and adjuvant chemoradiation. One patient developed liver, lung, pleural, and pericardial metastases (63 mo) and is currently (70 mo) alive under palliative treatment. Another developed recurrent cervical lymph node metastases and died of disease 8.5 years later. The youngest patient was disease-free at last follow-up 7 years later. Histologic features were very similar in all 3 cases and showed intimate admixture of compact basaloid cell nests with peripheral palisading, perivascular pseudorosettes, and a few scattered rhabdoid cells. Rhabdoid cells were more extensive in the metastasis in 1 case but formed a minor inconspicuous component in the primary tumors in all cases. Striking features common to all cases were (1) basaloid “blue” appearance at low power, (2) papilloma-like exophytic component, (3) extensive pagetoid surface growth with prominent denuding features, and (4) replacement of underlying mucous glands mimicking an inverted papilloma. Clear-cut origin from benign papilloma and overt squamous differentiation were lacking. Diffuse (2) or partial (1) p16 expression was noted, but all cases lacked human papillomavirus DNA by molecular tests. In situ hybridization was negative for Epstein-Barr virus. Immunohistochemistry showed diffuse expression of pancytokeratin. CK5 and vimentin showed intermingling of CK5+/vimentin− basaloid and CK5−/vimentin+ rhabdoid cells. Complete loss of nuclear SMARCB1 expression was seen in all cases including also the denuding carcinoma in situ–like surface lesions. To our knowledge, this variant of sinonasal carcinoma has not been reported before. The identical features in all 3 cases suggest a specific disease rather than a nonspecific dedifferentiated phenotype. Awareness of this rare variant and thus reporting of additional cases is necessary for defining its full morphologic and biological spectrum.

The oncofetal protein, insulin-like growth factor II messenger ribonucleic acid-binding protein 3 (IMP3), has been analyzed in many different tumors. Various studies have found that IMP3 is a marker for malignancy and is correlated with increased tumor aggressiveness and reduced overall survival. The diagnosis of pancreatic ductal adenocarcinoma (PDAC) in core needle biopsies can be challenging, and immunohistochemical markers are needed. We studied IMP3 expression in 177 core needle biopsies of the pancreas, including 112 PDACs, 55 cases with chronic sclerosing pancreatitis, and 10 biopsies with tumor-free pancreatic tissue without inflammation. An additional 18 biopsies of PDAC metastases (16 liver biopsies and 2 lymph node biopsies) were analyzed. To study IMP3 expression in large tissue sections, 45 pancreatic resection specimens (26 with PDAC and 19 with chronic sclerosing pancreatitis) were investigated. In contrast to normal or inflamed pancreatic tissue, which was negative in 47 of 65 (72.3%) cases and weakly positive in 15 of 65 (23.1%) cases, strong IMP3 expression was found in 99 of 112 (88.4%) PDACs. Therefore, sensitivity and specificity of IMP3 expression in the differential diagnosis of PDAC and chronic sclerosing pancreatitis using core needle biopsies were found to be 88.4% and 94.6%, respectively. These results were confirmed in the pancreas resection specimens. Furthermore, strong IMP3 expression was found in 17 of 18 (94.4%) of the PDAC metastases that were analyzed. Our study shows that IMP3 is an easy to use and potentially new immunohistochemical marker for the diagnosis of PDAC in core needle biopsies.