CSEM2404 - CSEM Resident Oral Abstract Presentations - An Unusual Presentation of an Exceedingly Rare Disease: The First Ever Reported Case of Hereditary Tumoral Calcinosis in a Canadian Indigenous Patient

Abstract: BACKGROUND
Hyperphosphatemic Hereditary Tumoral Calcinosis (HTC) is a rare syndrome of phosphate metabolism caused by FGF23/GALNT3/KLOTHO mutations which compromise FGF23 action and subsequently impair renal phosphate excretion.(1–4) Hyperphosphatemia leads to accumulation of CaCO3 and hydroxyapatite tumors in various tissues - classically bony surfaces subjected to trauma/inflammation.(5–9) The disease is inherited in an autosomal recessive pattern and most often reported in African or Middle-Eastern populations.(10–16) Treatment consists of a low-phosphate diet, phosphate-lowering medications, and anti-inflammatories.(9)

CASE PRESENTATION
MP is a 63-year-old female of the [blinded] Nation who presented with progressive neck pain and radiculopathy after a whiplash injury. Serial imaging revealed an expanding C2 mass, which yielded a “chalky fluid” on biopsy. HTC was suspected, but diagnosis was delayed 2 years due to atypical metabolic and clinical factors. Eventually, the patient developed characteristic hyperphosphatemia, impaired renal phosphate excretion, and multiple tumors.(fig1-4) The diagnosis of HTC was made and treatment was initiated. There is no known family history of HTC and genetic investigations are underway.

DISCUSSION
This is, to our knowledge, the first reported case of TCS in a person of Canadian Indigenous Heritage. It remains to be seen if this case will identify a de-novo mutation or a new genetic kinship.
With less than 100 case reports worldwide, diagnosis and management of HTC is hindered by poor recognition and limited experimental data.(2,9,12,17) This challenge is compounded by atypical presentations such as MP. It is important for providers to recognize this extremely rare disease early to prevent progression and fibrosis of tumors.(2,5,9,17)