Tumor calcinosis is a rare pathology characterized by circumscribed calcifications in the periarticular connective tissue. They are composed mainly of crystals of hydroxyapatite and amorphous calcium phosphate [1]. This term has usually been employed to describe metastatic periarticular calcification secondary to renal failure, hyperparathyroidism, hypervitaminosis D, and milk-alkali syndrome [2].

Herein, we present the case of a 58-year-old female who consulted for a tumor in the lower anterior region of the knee, subcutaneous, of months of evolution, bothering the flexion of the joint. She suffered from multiple sclerosis with a favorable evolution without medication and osteoporosis with multiple vertebral fractures. Treatment consisted of risedronate and calcifediol. On physical examination, a nodule of about 2–3 cm, infrapatellar, subcutaneous, mobile, not attached to deep planes, with a hard consistency was observed. With the diagnosis of a probable epidermal inclusion cyst, surgical excision was indicated, and the sample was sent for a histopathological study. The histological sections examined (Figs. 1a and 1b) corresponded to soft tissue, consisting of subcutaneous tissue and connective tissue, showing multiple calcified nodular formations associated with a histiocytic reaction with multinucleated giant cells.

Figure 1: (a) Subcutaneous and connective tissue revealing multiple calcified nodular formations (H&E, 20×). (b) Calcified nodular formations associated with a histiocytic reaction with multinucleated giant cells (H&E, 20×).

The histological picture was compatible with a cutaneous calcium deposit (calcinosis cutis), and the preferential involvement at the level of periarticular soft tissue could correspond to tumoral calcinosis. With this diagnosis, the patient was referred to internal medicine, where they assessed the extent of the disease and adjusted the treatment.

Histologically, these lesions are identical regardless of etiology, which explains why periarticular calcifications are often referred to as tumoral calcinosis. Surgical resection is the usual treatment, yet recurrences are frequent after incomplete excisions or in cases with osteoblastic activity [3].

REFERENCES

1. Olsen KM, Chew FS. Tumoral calcinosis:Pearls, polemics, and alternative possibilities. Radiogr Rev Publ Radiol Soc N Am Inc. 2006;26:871-85.

2. Franco M, Van Elslande L, Passeron C, Verdier JF, Barrillon D, Cassuto-Viguier E, et al. Tumoral calcinosis in hemodialysis patients:A review of three cases. Rev Rhum Engl Ed. 1997;64:59-62.

3. Yano H, Kinjo M. Tumoral calcinosis. Cleve Clin J Med. 2021;88:208-9.