Normophosphatemic familial tumoral calcinosis: description of a case with phosphate lowering therapy

Normophosphatemic familial tumoral calcinosis (NFTC) is characterized by cutaneous calcifications with no metabolic disorders; it manifests in the first years of life; associated with mutations in SAMD9 gene. Chronic trauma and transient hyperphosphatemia play a leading role in calcification formation.

Surgical treatment can remove calcifications, but it does not prevent recurrence and can cause complications. Various conservative therapy is used. Lowering of blood phosphate levels is considered a promising pathogenetic treatment method.

We present a clinical case of a patient with NFTC associated with the homozygous variant p.E1200K in SAMD9. A characteristic feature of our patient is the presence of multiple calcifications not only in the areas of injury (limbs), but also in areas of acne (face), as well as particularly active progression of the disease during puberty. A reduction in calcification size was observed after one year of continuous hypophosphatemic therapy (aluminum hydroxide and sevelamer 800 mg). The effectiveness of this therapy is debatable and limited by both poor patient tolerability of sevelamer and poor adherence.

This is the first description of a patient with molecularly confirmed NFTC in Russia. A precise diagnosis allowed us to clarify the pathogenetic mechanism of calcification formation and propose treatment options.

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