Abstract

Background: While dermatomyositis (DM) is generally considered to be an idiopathic inflammatory myopathy, amyopathic variants exist. A rare distinctive variant known as “Wong-type” is characterized clinically by an erythrodermic papulosquamous eruption, histologically by porokeratosis-like columnar dyskeratosis, and may mimic pityriasis rubra pilaris (PRP). Previously published case reports have remarked upon the presence of these distinctive findings in the absence of the typical findings of DM and/or myositis. Case report: We describe a 67-year-old Caucasian woman with a medical history of ovarian cancer (~3 years prior) and rosacea. The rosacea showed progression despite treatment with triamcinolone and betamethasone. She presented with a photo distributed rash in the scalp and retro auricular areas. A shave biopsy of a “psoriasiform eruption” from the back revealed vacuolar interface dermatitis, follicular plugging reminiscent of cornoid lamellae, reduplication of the basement membrane, a mild perivascular lymphocytic infiltrate, and increased dermal mucin. The morphologic alterations were suspicious for Wong-type DM, thus prompting clinical evaluation to assess for an unusual presentation of DM. Clinical follow up showed Gottron’s papules without evidence of a heliotrope rash or myositis. A myositis-specific workup was performed which included (but not limited to) testing for Anti-Jo, Anti-Mi-2, ANA, and CK with results within normal limits. Administration of topical corticosteroids resulted in improvement of the rash and she remained clinically amyopathic. Conclusion: It is important to recognize Wong-type DM as a clinical mimic of other papulosquamous diseases. Similarly, the histologic changes in the epidermis may overshadow the subtle vacuolar change critical for the diagnosis. Careful clinicopathologic correlation is required to provide an accurate diagnosis.

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