Recurrent Unresectable Malignant Granular Cell Tumor With Response to Pazopanib.

Malignant granular cell tumors (MGCTs) are rare and aggressive variants of granular cell tumors. They usually involve the head and neck region, skin and soft tissues. There are no standard therapeutic guidelines for management; however, surgical resection, whenever feasible, is considered to be first line. We report a patient with recurrent unresectable MGCT of lower lip who responded to pazopanib monotherapy. This drug has been recently approved for the treatment of advanced soft tissue sarcomas. It is a potent oral tyrosine kinase inhibitor and acts on multiple receptors, including vascular endothelial growth factor receptor (VEGFR), epidermal growth factor receptor (EGFR), c-kit, platelet-derived growth factor receptor (PDGFR) and fibroblast growth factor receptor (FGFR). Due to the overexpression of multiple genes by the tumor and multiple targets of this drug, it is difficult to establish the mechanism of action responsible for disease response.