Dialysis as a Treatment Option for a Patient With Normal Kidney Function and Familial Tumoral Calcinosis Due to a Compound Heterozygous FGF23 Mutation

Abstract

Primary tumoral calcinosis is a rare autosomal recessive disorder characterized by ectopic calcified tumoral masses. Mutations in 3 genes (GALNT3, FGF23, and KL) have been linked to this human disorder. We describe a case of a 28-year-old man with a history of painful firm masses over his right and left gluteal region, right clavicle region, knees, and left elbow. Biochemical analysis disclosed hyperphosphatemia (phosphate, 9.0 mg/dL) and normocalcemia (calcium, 4.8 mg/dL), with normal kidney function and fractional excretion of phosphate of 3%. Parathyroid hormone was suppressed (15 pg/mL), associated with a low-normal 25-hydroxyvitamin D (26 ng/mL) concentration but high 1,25-dihydroxyvitamin D concentration (92 pg/mL). Serum intact FGF-23 (fibroblast growth factor 23) was undetectable. Genetic analysis revealed tumoral calcinosis due to a compound heterozygous mutation in FGF23, c.201G>C (p.Gln67His) and c.466C>T (p.Gln156*). Due to lack of other treatment options and because the patient was facing severe vascular complications, we initiated a daily hemodialysis program even in the setting of normal kidney function. This unusual therapeutic option successful controlled hyperphosphatemia and reduced metastatic tumoral lesions. This is a report of a new mutation in FGF23 in which dialysis was an effective treatment option for tumoral calcinosis with normal kidney function.

Keywords: Case report; FGF23 mutation; extra-osseous calcifications; fibroblast growth factor 23 (FGF-23); genetic disease; hemodialysis; hyperphosphatemia; metabolic disorder; mutation; tumoral calcinosis.

Figure 1

Metastatic calcifications presenting as firm solid masses over the patient’s (A) gluteal region and knees, (B) right clavicle, and (C) left elbow regions. Image diagnostic methods including radiographs and computed tomography revealed giant calcified masses in the (D) right hip, (E) thigh, (F) left elbow, and (G) near the right clavicle, as well as vascular calcifications.

Figure 2

(A) Evolutive laboratory parameters of serum phosphate and ionized calcium concentrations from hospital admission to the last month of hemodialysis therapy. After 24 months of hemodialysis treatment, there was a substantial decrease in tumoral mass volume of the (B) gluteal region and knees, (C) right clavicle, and (D) left elbow regions.