A story of cutaneous pearls: asymptomatic plaques and nodules on buttocks associated with cutaneous calcinosis

Introduction
Calcinosis cutis is a rare disorder characterized by an aberrant calcium deposition in the skin and subcutaneous tissue. Clinical manifestations vary from localized papules and nodules to debilitating lesions that can involve large areas of the body. Idiopathic calcinosis cutis is the rarest subtype.

Objective
To present a rare morphological form of idiopathic calcinosis cutis on the right side of the buttocks occurring in an uncommon age.

Case Report
A 62-year-old woman presented with asymptomatic plaques and nodules on the buttocks for the past 3 years. She had a history of repeated whitish discharge from the lesions. The cutaneous examination showed ill-defined, hyperpigmented plaques, studded with white-coloured nodules and papules. Her laboratory investigations such complete haemogram, liver function tests, renal function tests, serum electrolytes, calcium (9.2 mg/dl) and phosphorus (3 mg/dl) levels were within the normal limits. The histopathological examination of the biopsied tissue showed basophilic calcium deposits extruding through the epidermal layers. The von Kossa stain showed black deposits.

Conclusions
Idiopathic calcinosis cutis is a skin calcification with no known aetiology and an unclear pathogenesis. Idiopathic calcinosis cutis of the buttocks is very rare in old age. Differentiation of idiopathic calcinosis cutis from other causes of soft tissue calcifications, nocardiosis and parasitic infestations is essential. Knowledge of this benign condition can prevent unnecessary diagnostic tests and aggressive medical treatment.