Metastatic < b > < i > SMARCB1 < /i > < /b > ( < b > < i > INI-1 < /i > < /b > )-Deficient Sinonasal Carcinoma Diagnosed by Endobronchial Ultrasound-Guided Fine-Needle Aspiration (EBUS-FNA): A Potential Diagnostic Pitfall and Review of the Literature

SMARCB1 (INI-1)-deficient sinonasal carcinoma is a rare entity within the subgroup of poorly differentiated sinonasal tract carcinomas. As there are only two papers describing the cytologic features of this entity, herein we describe the unique cytomorphologic features of a pulmonary metastasis of this tumor and include the differential diagnosis based on tumor location. The patient was a 53-year-old male who initially presented with sinus congestion and vision changes including left-eye proptosis and diplopia. The initial biopsy of the ethmoid-centered sinonasal mass was non-keratinizing squamous cell carcinoma based on strong immunoreactivity with p40 and absence of immunoreactivity for chromogranin, synaptophysin, p16, and EBER. However, the final diagnosis of the surgical resection was amended toSMARCB1 (INI-1)-deficient sinonasal carcinoma after additional immunohistochemical stains were performed. Post-primary resection, follow-up computed tomography imaging revealed significant interval progression of a solitary, initially indeterminate 1-cm lung nodule in the left upper lobe. Endobronchial ultrasound-guided fine-needle aspiration with concomitant core-needle biopsy was performed. Rapid on site evaluation of cytologic smears revealed a hypercellular specimen consisting of sheets of epithelioid cells with very scant to absent cytoplasm, ill-defined cell borders, enlarged fragile nuclei, and areas of nuclear molding. Mitotic figures were present. Other areas showed tumor...
Source: Acta Cytologica - Category: Cytology Source Type: research