Tumoral calcinosis. Observations during six years

Hyperphosphatemic familial tumoral calcinosis: genetic models of deficient FGF23 action

Hyperphosphatemic familial tumoral calcinosis (hFTC) is a rare disorder of phosphate metabolism defined by hyperphosphatemia and ectopic calcifications in various locations. To date, recessive mutations have been described in three genes involving phosphate metabolism: FGF23, GALNT3, and α-Klotho, all of which result in the phenotypic presentation of hFTC. These mutations result in either inadequate intact fibroblast growth factor-23 (FGF23) secretion (FGF23 or GALNT3) or resistance to FGF23 activity at the fibroblast growth factor receptor/α-Klotho complex (α-Klotho). The biochemical consequence of limitations in FGF23 activity includes increased renal tubular reabsorption of phosphate, hyperphosphatemia, and increased production of 1,25-dihydroxyvitamin D. The resultant ectopic calcifications can be painful and debilitating. Medical treatments are targeted toward decreasing intestinal phosphate absorption or increasing phosphate excretion; however, results have been variable and generally limited. Treatments that would increase FGF23 levels or signaling would more appropriately target the genetic etiologies of this disease and perhaps be more effective.

Differential response of idiopathic sporadic tumoral calcinosis to bisphosphonates

CONTEXT

Tumoral calcinosis is a disorder of phosphate metabolism characterized by ectopic calcification around major joints. Surgery is the current treatment of choice, but a suboptimal choice in recurrent and multicentric lesions.

AIMS

To evaluate the efficacy of bisphosphonates for the management of tumoral calcinosis on optimized medical treatment.

SETTINGS AND DESIGN

The study was done in the endocrine department of a tertiary care hospital in South India. We prospectively studied two patients with recurrent tumoral calcinosis who had failed therapy with phosphate lowering measures.

MATERIALS AND METHODS

After informed consent, we treated both patients with standard age adjusted doses of bisphosphonates for 18 months. The response was assessed by X ray and whole body 99mTc-methylene diphosphonate bone scan at the beginning of therapy and at the end of 1 year. We also estimated serum phosphate levels and urinary phosphate to document serial changes.

RESULTS

Two patients (aged 19 and 5 years) with recurrent idiopathic hyperphosphatemic tumoral calcinosis, following surgery were studied. Both patients had failed therapy with conventional medical management - low phosphate diet and phosphate binders. They had restriction of joint mobility. Both were given standard doses of oral alendronate and parenteral pamidronate respectively for more than a year, along with phosphate lowering measures. At the end of 1 year, one of the patients had more than 95% and 90% reduction in the size of the lesions in right and left shoulder joints respectively with total improvement in range of motion. In contrast, the other patient (5-year-old) had shown no improvement, despite continuing to maintain normophosphatemia following treatment.

CONCLUSIONS

Bisphosphonate therapy in tumoral calcinosis is associated with lesion resolution and may be used as a viable alternative to surgery, especially in cases with multicentric recurrence or treatment failure to other drugs.

Miscellaneous non-inflammatory musculoskeletal conditions. Hyperphosphatemic familial tumoral calcinosis (FGF23, GALNT3 and αKlotho)

Familial tumoral calcinosis (TC) is a rare disorder distinguished by the development of ectopic and vascular calcified masses that occur in settings of hyperphosphatemia (hFTC) and normophosphatemia (nFTC). Serum phosphorus concentrations are relatively tightly controlled by interconnected endocrine activity at the level of the intestine, kidney, and skeleton. Discovering the molecular causes for heritable forms of hFTC has shed new light on the regulation of serum phosphate balance. This review will focus upon the genetic basis and clinical approaches for hFTC, due to genes that are related to the phosphaturic hormone fibroblast growth factor-23 (FGF23). These include FGF23 itself, an FGF23-glycosylating enzyme (GALNT3), and the FGF23 co-receptor α-Klotho (αKL). Our understanding of the molecular basis of hFTC will, in the short term, aid in understanding normal phosphate balance, and in the future, provide potential insight into the design of novel therapeutic strategies for both rare and common disorders of phosphate metabolism.

Tumoral calcinosis: a case report and review of the literature

Tumoral calcinosis is an uncommon and seemingly unrecognised disease of obscure aetiology. A case in a young Caucasian boy aged 14 is reported. The characteristic clinical features, radiological and pathological findings are described. The condition must be differentiated from other varieties of pathological calcification such as chronic vitamin D intoxication, the milk-alkali syndrome, chronic nephritis, primary hyperparathyroidism, calcinosis universalis, calcinosis circumscripta and dystrophic calcification.