Pseudoxanthoma elasticum (PXE)-like calcification in adult dermatomyositis

A case of pseudoxanthoma elasticum (PXE)-like calcification in adult dermatomyositis (DM) is described. The patient was a 38-year-old woman with a history of dermatomyositis for 3 months. Yellowish, hard, papulo-plaque lesions, which looked like those of pseudoxanthoma elasticum, were noted on her left axilla. Calcium deposition was confirmed by X-ray, histopathological, and electron microscopic examinations. Histopathological and histochemical examinations showed acicular calcium deposition in the middle and deep dermis surrounded by mucin. Electron microscopic examination revealed that the calcium deposition was not on collagen fibers. These morphological features were distinct from those of PXE. We proposed the possibility that degenerated mucin or degenerated elastic fiber might result in subsequent calcium deposition in reticular calcinosis in adult DM. The calcification clinically disappeared without any specific treatment except for prednisolone and cyclophosphamide.