Hyperphosphatemic Familial Tumoral Calcinosis.

Hyperphosphatemic familial tumoral calcinosis (HFTC) is a rare, autosomal recessive condition characterized by fibroblast growth factor 23 signaling pathway dysregulation, hyperphosphatemia and ectopic calcifications (which manifest as joint motion limitations), inflammatory bony pain, and disability. Given the rarity and multiorgan involvement of HFTC, a multidisciplinary approach including Dermatology, Ophthalmology, Dentistry, Nephrology, Endocrinology, Rheumatology, and Genetics is necessary for diagnosis and treatment. We present a multidisciplinary diagnostic and treatment approach for a patient with HFTC due to a GALNT3 gene mutation with unique imaging highlighting the extent of calcinosis seen in HFTC. In this case study, a 34-year-old female patient found to have HFTC was first evaluated at an outpatient academic dermatology center in October 2020 and studied for 1 year. Genetic testing revealing a homozygous c.1319C > A variant in GALNT3 predicted to result in a missense mutation p.Ala440Glu. HFTC should be considered for patients presenting with diffuse calcinosis cutis-like features, and a multidisciplinary evaluation should be pursued.