Cutaneous and Systemic Findings Associated With Nuclear Matrix Protein 2 Antibodies in Adult Dermatomyositis Patients

Objective. To characterize the cutaneous and systemic clinical phenotype of dermatomyositis patients with antinuclear matrix protein 2 (anti-NXP-2) antibodies. Methods. We conducted a retrospective cohort analysis of 178 dermatomyositis patients seen at the Stanford University Clinic. An electronic chart review employing a keyword search strategy was performed to collect clinical and laboratory data. Anti-NXP-2 antibodies were assayed by immunoprecipitation using NXP-2 produced by in vitro transcription/translation. Results. Antibodies to NXP-2 were detected in 20 of the 178 patients (11%). Anti-NXP-2 antibodies were associated with male sex (50% versus 25%; P = 0.02), dysphagia (74% versus 39%; P = 0.006), myalgia (89% versus 52%; P = 0.002), peripheral edema (35% versus 11%; P = 0.016), and calcinosis (37% versus 11%; P = 0.007). These patients were less likely to be clinically amyopathic (5% versus 23%; P = 0.08). Five of the 20 patients with anti-NXP-2 antibodies (25%) had an associated internal malignancy. No other cutaneous characteristics were associated with anti-NXP-2 antibodies, except a decreased frequency of Gottron's sign (44% versus 75%; P = 0.012) and a greater likelihood of having mild skin disease. Conclusion. Dermatomyositis patients with anti-NXP-2 antibodies have a distinct and often severe systemic phenotype that includes myalgia, peripheral edema, and significant dysphagia, despite having milder inflammatory skin disease.