Dermatomyositis and mucinosis.

Background: Mucin deposition is a common feature in autoimmune collagen diseases including dermatomyositis. Nevertheless, clinical manifestations of mucinosis are uncommon in patients with dermatomyositis. Two cases of mucinosis associated with dermatomyositis are reported.

Patients: A 53-year-old woman presented with symmetrical plaques on the upper limbs formed by the coalescence of small, violaceous papules. In addition, she showed the typical cutaneous and muscle features of dermatomyositis. A 44-year-old woman with dermatomyositis of 5 years' evolution developed linear, flesh-colored papules across the flexural creases of her palms and fingers.

Results: Skin biopsy of the upper limb lesions in the first patient showed epidermal changes compatible with dermatomyositis and dermal mucin deposition. Histopathologic examination of the palmar lesions of the second patient showed less intense epidermal changes of dermatomyositis and dermal mucin deposition.

Conclusions: Mucin deposition in patients with dermatomyositis may have an unusual clinical presentation, and it should be considered in the differential diagnosis of atypical cutaneous lesions in these patients.