[1788] Cytological, Histological, and Immunohistochemical Findings of Pulmonary Carcinomas with Basaloid Features

JP Crapanzano, K Loukeris, AC Borczuk, A Saqi. Columbia University Medical Center, New York, NY; Weill Cornell Medical Center, New York, NY

Background: Pulmonary basaloid carcinoma (BC), a variant of large cell, non-small cell carcinoma (NSCC), and basaloid squamous cell carcinoma (BSQCC) can show features similar to small cell carcinoma (SCC) and large cell neuroendocrine carcinoma (LCNEC). Distinction from SCC, especially on FNA, is therapeutically relevant. We describe cytological, histological, and immunohistochemical features of BC and BSQCC.
Design: Cytologic features were documented in the cytologic preparations. Similar features and as well as architecture were evaluated in resections. Immunohistochemical results were recorded. Histologically confirmed BC (n=3) and BSQCC (n=3) were included. 5 SCC FNAs, 4 with histologic follow-up, were compared.
Results: BC/BSQCC FNAs: mostly tightly cohesive clusters (n=4) or single cells and in clusters (n=2) with a predominance of clusters. Cytologic features were similar: palisading (n=6), crush artifact (n=6), hyperchromasia (n=5), nuclear molding (n=6; focal/rare in 4/6), nucleoli, usually pinpoint (n=3), scant cytoplasm (n=6), necrosis (n=5), apoptosis (n=4), squamous differentiation (n=1). BSQCC tended to have occasional larger cells, including keratinizing cells in 1 case. Histologic sections: neuroendocrine architectural patterns, including organoid arrangements (n=5); palisading (n=5). SCC FNAs: cells predominantly single cells (n=3) or clusters and single cells (n=2), rare palisading (n=4), crush (n=5), hyperchromasia (n=5), nuclear molding (n=5; prominent in 3/5), absent/rare inconspicuous nucleoli (n=5), scant cytoplasm (n=5), necrosis (n=5), apoptosis (n=5). SCC histologic sections: solid sheets (n=3); organoid (n=1); palisading (n=1).

Immunostaining Profile of BC, BSQCC, and SCC
2-+* (- on histo)focal +* (- on histo)-**
3++focal weak++
5+*weak +*-*+*+*equivocal*-*
*Immunostain on FNA; **Immunostain on both FNA and histology

Conclusions: BC and BSQCC show overlapping features with SCC and LCNEC in cytological and histological specimens. Unlike SCCs, BC/BSQCC lack prominent nuclear molding, show greater numbers of tightly cohesive clusters, and demonstrate palisading of cells along the periphery of nests. p63 (+), HMWCK (+), and TTF-1 (-) are helpful in distinguishing BC/BSQCC from SCC/LCNEC.
Category: Pulmonary

Wednesday, March 24, 2010 9:30 AM

Poster Session V # 252, Wednesday Morning


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