Objective: To investigate the clinical and pathological characteristics of dermatomyositis with muscular perifascicular atrophy (PFA).
Methods: A series of 104 consecutive patients clinically and pathologically diagnosed as dermatomyositis by muscle biopsy in our laboratory from December, 2003 to August, 2011, were enrolled in this study. Muscle biopsy of all the enrolled patients had shown PFA of muscle fibers.
Results: Among the 104 patients, 34 were males and 70 were females with a mean age of 45 years old. Among them, 8 cases had normal electromyogram; 42 had normal serum creatine kinase level; 11 were diagnosed as carcinoma; 75 were found to be combined with interstitial lung disease (ILD). Based on morphologic changes of muscle biopsy, they were divided into pure PFA group with 54 cases and PFA plus focal damage group with 50 cases. Compared with the pure PFA group, there was prominent mononuclear cell infiltration into perimysial intermediate sized vessels and membrane attack complement (MAC) deposition in the intramuscular capillaries in the PFA plus group. Skin biopsy had been taken in 12 cases together with muscle biopsy and had shown the "border effect" of both PFA and interface dermatitis in muscle and skin.
Conclusions: Our study suggests that chronic immune vascular damage and insufficiency in dermatomyositis may cause ischemia and focal myofiber damage in "watershed" regions. The incidence of ILD in our dermatomyositis patients with PFA is high.