Acquired perforating calcific collagenosis in a drug addict with rhabdomyolysis and transient hypercalcemia.

Acquired perforating calcific collagenosis (APCC), which is characterized by the calcification of dermal collagen fibers with subsequent transepidermal elimination and perforation, is an extremely rare entity. Thus far, it has only been reported in a patient with direct contact exposure to calcium chloride. Here, we report a unique case of APCC occurring in a drug addict admitted for rhabdomyolysis. The present case is a 20-year-old male patient hospitalized for drug-related rhabdomyolysis and multiple organ damage. During hospitalization, he gradually developed unusual skin rashes. There were multiple confluent umbilicated and keratotic erythematous to brownish papules and plaques with scratch-like linear plaques on his lower abdomen, inguinal areas and gluteal sulci. Also, multiple well-demarcated flesh-colored rough, hard and thin plaques with a "crepe paper"-like texture were found on the bilateral popliteal fossae, olecranon fossae and axillae. The histopathology of two biopsied lesions demonstrated acquired perforating calcific collagenosis. The lesions appeared during the rhabdomyolysis-related hypercalcemia phase and resolved spontaneously after the calcium level returned to normal. This is the first reported case of disseminated APCC occurring during transient hypercalcemia due to rhabdomyolysis.