Abstract

Background Understanding whether specific histopathologic features on skin biopsy are predictive of systemic associations in dermatomyositis would be useful to guide clinical screening. Methods Via retrospective medical record search, clinical and laboratory findings of patients with dermatomyositis were documented. Existing skin biopsy slides were re-reviewed blindly. Results Of all biopsy specimens (n=42), the most frequent histopathological finding was vacuolar interface dermatitis (95%). Other features included perivascular lymphocytic infiltrate (71%), increased dermal mucin (40%), vessel wall thickening (12%), follicular plugging (9.5%) and dermal sclerosis (7%). Neutrophilic infiltrate was observed in 3 biopsies from a patient with adualimumab-associated DM. Vasculitis was not observed. There was no statistically significant difference in the presence of any histopathological feature and that of various systemic manifestations [i.e. myopathy, interstitial lung disease (ILD) and malignancy]. However, we observed that dense lichenoid infiltrate rather than pauci-inflammatory changes correlated with severe itching (p <0.001) Patients with MDA-5 antibodies were significantly more likely to have vasculopathy than those without (p=0.029*). Conclusions No dermatopathological feature was reliably predictive of myopathy, ILD or malignancy. This finding implies that regardless of histopathologic findings, patients should be screened for associated conditions, as clinically indicated.

Financial Disclosure: No current or relevant financial relationships exist.