Nodulo-Infiltrative Subtype of Basal Cell Carcinoma With Follicular and Sebaceous Differentiation

Basal cell carcinoma (BCC) is the most common cancer and typically presents as a slow-growing pearly papule with telangiectasias on sun-damaged skin, particularly the head and neck. Although BCC metastasizes rarely, delayed treatment can lead to significant local tissue destruction. Common subtypes of BCC include nodular, micronodular, superficial, and infiltrative. Rarer variants with sebaceous or follicular differentiation have also been reported. We describe a case of a 69-year-old woman with a 7 mm red papulonodule on the upper back. Shave biopsy revealed nodulo-infiltrative BCC with sebaceous and follicular differentiation. Histopathology showed sebaceous cells with vacuolated, foamy cytoplasm expressing epithelial membrane antigen (EMA) and carcinoembryonic antigen (CEA). Follicular differentiation was characterized by infundibular cyst-like formations and cellular arrangements mimicking telogen follicles. These rare subtypes, particularly in combination, pose diagnostic challenges. Increased awareness of their unique characteristics is essential to avoid misdiagnosis and ensure appropriate management. Further studies are needed to clarify their clinical behavior and outcomes.