Abstract
Introduction: Hyperphosphatemic familial tumoural calcinosis (HFTC) is a rare autosomal recessive disorder characterised by ectopic calcium phosphate deposition around the joints due to mutations affecting phosphate regulation.
Case outline: We report a 7-year-old boy who presented with hip pain and swelling, mimicking malignancy. Imaging revealed a large lobulated soft tissue mass involving the left iliac fossa and pelvic musculature. The FDG-PET and MRI findings suggested a neoplastic lesion, but the FNAC revealed only calcific debris. Biochemical analysis revealed elevated serum phosphorus levels and low PTH. Whole-exome sequencing identified a homozygous likely pathogenic mutation in GALNT3 (c.840T>A; p.Cys280Ter). Medical management included phosphate binders and acetazolamide. Despite initial improvement, recurrence occurred one year later. Surgical options were deemed high-risk and conservative treatment was continued.
Conclusion: This case highlights the importance of considering HFTC in the differential diagnosis of calcified soft tissue masses in children and the role of genetic testing in diagnosis and management.
References
Pakasa NM, Kalengayi RM. Tumoral calcinosis: a clinicopathological study of 111 cases with emphasis on the earliest changes. Histopathology. 1997;31(1):18–24.
El Houss S, LRhorfi N, El Yousfi Z, El Haddad S, Chat L, Allali N, et al. Hyperphosphatemic familial tumoral calcinosis mimicking a cystic hemo-lymphangioma on MRI. Radiol Case Rep. 2022;17(12):4603–7.
Anilkumar A, Högler W, Bursell J, Nadar R, Ryan F, Randell T, et al. Successful treatment approaches for tumoral calcinosis in children and young people: a condition of diverse pathogenesis. Bone. 2024;182:116289. doi:10.1016/j.bone.2024.117049.
Cavaliere RJ, Lotufo CD, Kruse DL, Sachs BD, Stone PA. Primary tumoral calcinosis in a pediatric patient: a rare presentation. J Foot Ankle Surg. 2020;59(6):1313–7.
Topaz O, Shurman DL, Bergman R, Indelman M, Ratajczak P, Mizrachi E, et al. Mutations in GALNT3, encoding a protein involved in O-linked glycosylation, cause familial tumoral calcinosis. Nat Genet. 2004;36(6):579–81.
Ichikawa S, Imel EA, Kreiter ML, Euro L, Rupar T, Fraser WD, et al. A homozygous missense mutation in human GALNT3 causes familial tumoral calcinosis. J Bone Miner Res. 2007;22(1):163–70.
Olsen KM, Chew FS. Tumoral calcinosis: pearls, polemics, and alternative possibilities. Radiographics. 2006;26(3):871–85.
Benet-Pagès A, Orlik P, Strom TM, Lorenz-Depiereux B. An FGF23 missense mutation causes familial tumoral calcinosis with hyperphosphatemia. Hum Mol Genet. 2005;14(3):385–90.
Frishberg Y, Topaz O, Bergman R, Indelman M, Ratajczak P, Mizrachi E, et al. Identification of a recurrent mutation in GALNT3 demonstrates that hyperostosis-hyperphosphatemia syndrome and familial tumoral calcinosis are allelic disorders. J Clin Endocrinol Metab. 2005;90(9):5515–20.
Courpron P. Tumoral calcinosis. Clin Orthop Relat Res. 1970;(69):265–80.
Sprecher E. Familial tumoral calcinosis: from characterization of a rare phenotype to the pathogenesis of ectopic calcification. J Invest Dermatol. 2010;130(3):652–60.
Fathi I, Sakr M. Review of tumoral calcinosis: a rare clinicopathological entity. World J Clin Cases. 2014;2(9):409–14.
Mak RH. Phosphate metabolism and disorders. In: Kher KK, Schnaper HW, Greenbaum LA, editors. Clinical Pediatric Nephrology. 3rd ed. Boca Raton (FL): CRC Press; 2017. p. 507–21.