All that is squamoid is not squamous: A rare case of Squamoid Eccrine Ductal Carcinoma presenting as an intranasal mass

Abstract Introduction/Objective Squamoid eccrine ductal carcinoma (SEDC) is a rare adnexal tumor that poses diagnostic challenges because of the rarity, variable clinical presentation, and misdiagnosis on superficial biopsy sampling. Methods/Case Report We report a 52-year-old immunosuppressed male, status-post kidney and heart transplants who presented with an anterior nasal mass, the biopsy of which was interpreted as squamous cell carcinoma (SCC). Resection revealed a 2.5cm intranasal mass eroding through the hard palate. Histology showed a biphasic tumor arising from nasal vestibular skin with a superficial squamoid component (p40 positive) and a deeply invasive component demonstrating ductal differentiation (CEA positive) consistent with SEDC. SEDC has a predilection towards skin of head and neck region but SEDC presenting as an intranasal mass has not been reported. In our case, the tumor arose from nasal vestibular skin with destructive bony invasion within the nasal cavity. The patient’s long- term immunosuppression likely played a role in the etiopathogenesis and aggressive progression of this tumor. Interestingly, he also had history of multiple sebaceous carcinomas and cutaneous T-cell lymphoma with no known genetic predisposition, further implicating immunosuppression as the key risk factor for development of his cutaneous malignances. Results (if a Case Study enter NA) N/A Conclusion This case exemplifies the potential diagnostic pitfalls in squamoid lesions of the head and neck. Given the overwhelming prevalence of conventional SCC, rarer tumors with squamous differentiation often are not considered in the differential diagnosis, especially of an intranasal mass. A superficial biopsy often is misdiagnosed as SCC due to the lack of representation of deep-seated ductal components. A high index of suspicion and adequate examination of deeper aspects of the lesion are imperative for accurate diagnosis.