Histopathological evidence of small-vessel vasculitis within the skin and lungs associated with interstitial pneumonia in an adult patient with dermatomyositis.

Dermatomyositis (DM) often has a poor prognosis, due to complications associated with malignancy or interstitial pneumonia (IP). It is uncommon to find histopathological small-vessel vasculitis within cutaneous lesions and pulmonary capillaritis in patients with DM. A 64-year-old woman was diagnosed with DM based on the presence of quadriparesis, typical heliotropic rash, Gottron's papules, increased serum levels of muscle enzymes and typical muscle biopsy findings. She also had associated IP, which subsequently developed into a rapidly progressive condition. We found a high titre of Krebs von den Lunge (KL)-6 in her serum. Measurement of serum KL-6 level is widely accepted as a diagnostic test to monitor the activity of interstitial lung diseases. Histopathological examinations of the cutaneous and lung-associated features showed small-vessel vasculitis. We suggest that investigation of KL-6 levels in patients with DM and associated conditions should be carried out to determine if raised KL-6 levels are useful at predicting outcome or severity of various features.