Mechanic Hands/Hiker Feet in a Patient With Amyopathic Dermatomyositis and Interstitial Lung Disease.

A 30-year-old African American woman with a history of interstitial lung disease presented with bilaterally symmetrical, nonpruritic, scaling and fissuring, hyperpigmented, lichenified plaques on her hands and feet. She reported occasional erythema of her face, intermittent erythema, and irritation of her eyes but denied any muscle weakness. A biopsy of the plantar first toe showed hyperkeratosis, striking alternating ortho- and parakeratosis with underlying apoptotic bodies. There was psoriasiform acanthosis without suprapapillary thinning, numerous apoptotic keratinocytes in all layers of the epidermis extending into the corneum that were out of proportion with the minimal interface inflammation. Colloidal iron and Alcian blue stains showed increased dermal mucin deposition. Given the clinical, histopathological, and supportive serological findings (positive anti-KU and anti-SSA), a diagnosis of clinically amyopathic dermatomyositis with mechanic hand/hiker feet (MH/HF) was rendered. The pseudocheckerboard pattern of MH/HF has been previously reported in only 4 patients. The most frequent associations with MH/HF are dermatomyositis and antisynthetase syndrome; however, our patient was negative for antiaminoacyl transfer RNA synthetase antibodies, a required criterion to diagnose antisynthetase syndrome. It is imperative to recognize MH/HF clinically and histopathologically because it may be an early indication of developing dermatomyositis or other connective tissue diseases, which would guide further workup and screening for systemic involvement of the disease, including interstitial lung disease.