A Novel Mutation in FGF23 Causing Severe Manifestation of Hyperphosphataemic Familial Tumoral Calcinosis

We present a 16-year girl, second issue of a consanguineous couple presented with painless symmetrical bony swellings around hips for 3 years. She lost 25 kg weight due to profound anorexia in the first year of illness and developed secondary amenorrhea. Last 7 months she had repeated generalized tonic clonic seizure due to hypocalcaemia. The bony swellings were located in both gluteal regions and were 30x35 cm2, hard and non tender. Mobility of hip joints were restricted. Except for severe wasting as a part of generalized cachexia other systemic examination was unremarkable. Investigations revealed anaemia (Hb-E trait), low albumin, low corrected calcium (during convulsions) otherwise normal, persistently high phosphate & vitamin-D level, normal iPTH & alkaline phosphatase (ALP), low serum ascorbic acid, normal ESR & CRP. X-ray & CT scan of pelvis showed large calcified mass in periarticular soft tissues. Biopsy confirmed presence of dystrophic calcification. Diagnosis of tumoral calcinosis was based on biochemical parameters, imaging and biopsy findings. A homozygous novel mutation in FGF homology domain: B-21 mutated from G to A at 232 in exon 2. As a result glutamic acid is replaced by lysine. Phosphate restricted diet and phosphate lowering agent improved biochemical paramaters. Surgical excision has been withheld. Contemporary manifestation of hFTC and Hb E trait; two disease of autosomal recessive inheritance in an individual makes it extremely rare. High index of suspicion is needed for early diagnosis and treatment.