Pembrolizumab Induced Tumor Shrinkage in Rare Osseous Metastasis of Basal Cell Carcinoma

Abstract

Cutaneous basal cell carcinoma (BCC) is an increasingly common malignancy with a rising incidence over the past decade. 1 BCC seldom exhibits lymphatic or hematogenous metastasis with an incidence of only 0.0028% to 0.5%. 2 There are only around 400 combined reports of metastatic spread of basal cell carcinoma (mBCC) since the 1980s, with hematogenous cases constituting a small minority. Typically, those diagnosed with hematogenous mBCC have a median survival of 8-14 months compared to those diagnosed with lymphatic mBCC, whose survival average is reported to be 3.6 years. 3 This case report focuses on a patient who presented with a basal cell carcinoma on his left shoulder that had metastasized to the spine. Ultimately, a multimodal therapeutic approach was required to bring the patient’s metastatic disease under control, including surgical resection, radiation therapy, and systemic therapy with hedgehog inhibitors (vismodegib, sonidegib) and novel employment of immunotherapy agents including pembrolizumab. To the author’s knowledge and based on our included literature review, this is the first case where pembrolizumab was used to treat osseous mBCC.