Hyperphosphatemic Familial Tumoral Calcinosis With a Large Hip Mass.

Hyperphosphatemic familial tumoral calcinosis (HFTC) is a rare autosomal recessive disorder that generally presents in the first two decades of life with ectopic calcification throughout the body. The underlying metabolic disorder is caused by a mutation in a gene responsible for regulating fibroblast growth factor 23 (FGF23) activity. Loss of regulation of FGF23 results in hyperphosphatemia resulting in the characteristic tissue calcinosis deposits, especially in periarticular locations. The diagnosis is made with imaging, hyperphosphatemia, and genetic testing. Medical and surgical treatments are recommended to reduce blood phosphate and remove the masses. A 35-year-old male presented with a painful left lateral hip mass that had been gradually enlarging over the past four months. X-rays showed amorphous calcific densities in the left hip consistent with tumoral calcinosis. Magnetic resonance imaging (MRI) noted a stable complex mass in the left posterior hip and ischio-femoral space consistent with tumoral calcinosis. He had an elevated phosphorus level of 6.0 mg/dL (reference range 2.5 to 4.5 mg/dL). Excision of the mass was successful and genetic testing showed a pathogenic variant in polypeptide N-acetylgalactosaminyltransferase 3 (