An unusual presentation of perforating metastatic calcinosis cutis.

A 37-year-old white man diagnosed with multiple myeloma was admitted for respiratory distress. He was found to have hypercalcemia (13.1 mg/dL), hyperphosphatemia (7.2 mg/dL), hyponatremia (121 mEq/L), and acute renal failure (serum urea nitrogen, 116 mg/dL; creatinine, 4.9 mg/dL). On hospital day 7, skin lesions over his elbows, wrists, and fingers were noticed and the dermatology department was consulted. Physical examination revealed 0.5- to 3.0-cm erythematous denuded patches with yellow crusts at the periphery that were localized to the bilateral interdigital web spaces, medial elbows, and volar wrists (Figure 1 and Figure 2). No oral mucosal or conjunctival findings were present. Results from skin biopsies of the lesions revealed focal epidermal necrosis with zones of amorphous basophilic material that focally appeared to perforate the epidermis (Figure 3). Results from Congo red and Verhoeff-van Gieson stains were negative, and results from Von Kossa stain were positive, confirming the perforating material as calcium. Ten days after initial dermatology examination, the patient's respiratory distress worsened and he subsequently died. Autopsy revealed diffuse pulmonary calcinosis and renal tubular calcification. As a result of the autopsy findings, the patient was diagnosed with perforating metastatic calcinosis cutis.