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Case Reports

Abstract

Wong-type dermatomyositis is an extremely rare variant with overlapping findings and symptoms of dermatomyositis and pityriasis rubra pilaris (PRP). It is associated with myositis and interstitial lung disease; its association with malignancy is not well established. Diagnosis is often delayed due to suspicion of other conditions including PRP, discoid lupus, and psoriasis. We present the case of a 61-year-old male on chronic prednisone with two years of joint pains and hyperkeratotic plaques on the palms and soles.  Biopsy favored psoriasiform versus subacute spongiotic dermatitis. He was given a presumptive diagnosis of psoriasis with psoriatic arthritis but failed to improve on guselkumab or risankizumab. He also developed muscle pain and transaminitis, prompting further workup. Repeat biopsy showed an unusual combination of vacuolar/interface dermatitis and stratum corneum changes characteristic of PRP (alternating “checkerboard” orthokeratosis and parakeratosis) and porokeratosis (cornoid lamellae). Subsequent review of the initial biopsy showed similar findings, albeit more subtle and with psoriasiform changes. Laboratory testing was significant for positive SSA-52 (anti-Ro), ANA (1:1280, nucleolar and speckled), and highly elevated CK peaking at 4,322. CT chest/abdomen/pelvis showed peripheral ground-glass opacities and no evidence of malignancy. Our patient was started on methotrexate, with improvement in his myositis. This was escalated to rituximab given the worsening of his rash and interstitial lung disease. He experienced marked improvement in symptoms and continues on rituximab with topical clobetasol, celecoxib, and a prolonged prednisone taper. This case highlights the importance of considering alternative diagnoses, and the value of repeat biopsy or reevaluation of previous biopsies, following nonresponse to or progression on well-established therapies.