Oncogenic Osteomalacia as the Initial Presentation of Pleural Epithelioid Hemangioendothelioma: A Case Report.

Epithelioid hemangioendothelioma (EHE) is a rare form of vascular neoplasm that can manifest with various symptoms or be discovered incidentally in asymptomatic patients. In this report, we describe a case of a 56-year-old male who presented with progressive lower limb weakness over four years. The evaluation revealed severe hypophosphatemia, an inappropriately normal fibroblast growth factor 23 C-terminal (cFGF-23) level, and a 30 x 20 mm hypermetabolic right pleural mass, which was subsequently proven to be EHE. Following tumor resection, the patient experienced complete recovery, with normalization of his serum phosphate levels and resolution of his presenting symptoms. This case highlights the association between EHE and oncogenic osteomalacia, a rare paraneoplastic syndrome.