Neglected basal cell carcinoma presenting with diffuse skeletal metastases

Metastatic basal cell carcinoma (mBCC) is exceedingly rare, with an estimated incidence of 0.0028% to 0.55%.1 Although the behavior of mBCC is poorly understood, the primary tumor typically exhibits aggressive histopathology, such as morpheaform, infiltrating, or basosquamous features. Basal cell carcinoma (BCC) usually metastasizes to regional lymph nodes (53%), lungs (33%), and bone (20%). Until a few years ago, the median survival after diagnosis was only 8 to 10 months. After the demonstration that more than 90% of BCC expressed abnormal Hedgehog signaling, 2 Hedgehog pathway inhibitors, vismodegib and sonidegib, were approved for advanced BCC.