Cytopathological characteristics of INI1-deficient undifferentiated carcinoma:report of a case and review of literature
HUA Fen
CHEN Ying-ting
GU Wen-xian
LI Ting
HE Chong-fang
CHENG Yu-qing
Abstract：Objective To explore the cytopathological features and differential diagnosis of INI1-deficient undifferentiated carcinoma. Methods A retrospective analysis of clinical and pathological data of one case of INI1-deficient undifferentiated carcinoma was conducted, and relevant literature was reviewed. Results The patient was a 58-year-old male who presented with chest tightness for one month. Cytological smears of the supraclavicular lymph node showed tumor cells distributed as single cells or clusters, with marked variation in cell size. Some tumor cells had clear cytoplasm or mucin-like cytoplasm, fine nuclear chromatin, slightly blurred nuclear periphery, and small nucleoli; some cells had scanty cytoplasm or fused, deeply stained nuclei with clear boundaries and no obvious nucleoli. Additionally, some cells had eosinophilic cytoplasm with renal-shaped or horse-shoe-shaped nuclei, resembling rhabdomyoblasts. Liquid-based cytology of pericardial effusion and paraffin sections showed a few atypical cells with increased nuclear-cytoplasmic ratio and prominent nucleoli. Histological examination of the lymph node biopsy showed sheets of poorly differentiated tumor cells with vacuolated nuclei, visible nucleoli, some with clear cytoplasm and rhabdomyoblast-like cells. Cytopathological immunohistochemistry showed loss of INI1 expression. The tumor cells from the supraclavicular lymph node biopsy showed loss of INI1 expression, retained BRG1 expression, positive CK, focal positive p63, mutant-type p53 expression, Ki-67 positive in 80% of cells, and negative for Desmin, MelanA, TTF1, NapsinA, p40, CK5/6, CK7, CK20, Villin, CD34, CD79a, Mum-1, SOX-10, and ALK. Conclusion INI1-deficient undifferentiated carcinoma is rare, and it should be differentiated from various tumors during cytological examination.
Keywords：INI1CarcinomaCytopathologyImmunohistochemistryRhabdomyoblast-like cells
Publication Date：2025-01-27
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：4( 64-66,77 )