Fatal Outcome of Widespread Cranial Basal Cell Carcinoma Due to Intraparenchymal Brain Extension in a Setting of Local Recurrences.

Basal cell carcinoma (BCC) is one of the most commonly encountered carcinomas; however, progression to invasive or locally advanced disease is extremely rare. The clinical course of locally advanced BCC is typically aggressive and has a poorer prognosis with variable survival. We present the case of a 58-year-old unhoused female with recurrent BCC of the left cranial vertex who underwent excision at an outside hospital. Intraoperative frozen section margins were negative for BCC; however, permanent sections demonstrated widespread residual tumor with morpheaform histology involving the parietal bone and aponeurosis at the deep margins. She subsequently underwent re-excision, multiple reconstructive procedures with grafts from the bilateral thighs, left forearm, and back, and immunotherapy with vismodegib. In September 2025, she presented with right upper extremity weakness and headache. Magnetic resonance imaging (MRI) revealed osteomyelitis and a left intra- and periventricular parietal fluid collection consistent with an abscess. She underwent left hemicraniectomy with wound debridement and full-thickness skin grafting. Histology demonstrated infiltrative nests and irregular strands of basaloid cells with peripheral palisading invading the skin, parietal bone, and brain parenchyma. Management included repeated wound debridement, full-thickness skin grafting, and consideration of adjuvant radiation to reduce recurrence after grafting. Three free-flap reconstructions with revisions were required because of infection, wound progression, and dehiscence. Persistent infection and a nonhealing wound ultimately precluded further surgical intervention. She was transitioned to comfort care and died in October 2025. This is a unique case of recurrent invasive and locally advanced BCC that supports the notion that this is an aggressive form of the more common indolent cancer seen in daily practice. Emphasis on early detection and intervention is vital in these particularly aggressive cases.