The cutaneous histology of dermatomyositis in collie dogs.

Cutaneous lesions of 36 collie dogs affected with dermatomyositis were reviewed. The most common histologic features were follicular atrophy and perifollicular inflammation in 30 dogs, which correlated with alopecia clinically. Other less common findings included formation of colloid bodies, basal cell vacuolation, and subepidermal vesiculation. Results indicated that the most diagnostic cutaneous histologic features of dermatomyositis may be follicular atrophy and inflammation.