An Atypical Presentation of Basal Cell Carcinoma: A Giant Verrucous Ulcer on the Upper Arm

Giant basal cell carcinoma (GBCC) is a rare and clinically aggressive subtype of BCC. We report an unusual case of a 71-year-old male with a 30-year history of a slowly enlarging tumor on the extensor surface of his left upper arm. The lesion presented as a giant, irregular ulceration measuring 12×10 cm with coalescing verrucous borders. Histopathological examination confirmed the diagnosis, revealing characteristic nests of basaloid cells with peripheral palisading and stromal retraction artifact in the dermis. Immunohistochemical staining was positive for Ber-EP4, CK15, Ki-67, Bcl-2. The patient was diagnosed with GBCC with Ulcer. Staging workup with computed tomography (CT) of the left humerus and axillary lymph node ultrasonography showed no evidence of metastasis. The patient was successfully treated with slow Mohs micrographic surgery. Subsequent histopathological assessment of the excised specimen confirmed tumor-free margins. At 12-month follow-up, no local recurrence was observed. This case highlights the importance of recognizing GBCC in uncommon locations and demonstrates the efficacy of slow Mohs technique for achieving complete excision in large, complex tumors.