Multiple ulcerations in anti-MDA5 dermatomyositis

A 47-year-old woman presented with multiple painful deep ulcerations on her back and left thigh for 4 months [Figures 1a and b]. A biopsy revealed vacuolar interface dermatitis with superficial and deep perivascular lymphocytic infiltrates, as well as thrombi present within small vessels [Figures 2a and b]. Laboratory tests indicated an antinuclear antibody titre of 1:100, and IgG against melanoma differentiation-associated gene 5 (anti-MDA5) was strongly positive. There was no evidence of muscle involvement, malignancy, or pulmonary complications. Consequently, the patient was diagnosed with anti-MDA5 amyopathic dermatomyositis (DM). Cutaneous ulceration, a hallmark feature of anti-MDA5 DM, reflects severe underlying vasculopathy, typically involving fingers, elbows, and knees. This case is notable for ulcerations occurring in atypical locations. Given the elevated risk of rapid progression to interstitial lung disease and poorer prognosis in anti-MDA5 DM individuals, prompt diagnosis and therapeutic intervention are critical to improve clinical outcomes.

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Figure 1a-b:

Deep ulcers exhibiting thick, hyperkeratotic crusts within areas of infiltrative erythema present on the lower back and left thigh.

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Figure 2:

a) Histopathology showing epidermal ulceration, interface changes with perivascular inflammation throughout the dermis. (Haematoxylin and eosin, 10×), b) Thrombotic occlusion within a single vessel was found in the deep dermis (Haematoxylin and eosin, 100×).

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