Abstract

Thymomas are rare tumors known for their association with myasthenia gravis. More recently, thymomas have been linked to a broader spectrum of paraneoplastic autoimmune phenomena, variably referred to as thymoma-associated multiorgan autoimmunity (TAMA) and paraneoplastic autoimmune multi-organ syndrome (PAMS). The most commonly reported cutaneous eruption in TAMA/PAMS is paraneoplastic pemphigus. However, there have recently been a number of case reports describing non-pemphigus interface dermatitides, including systemic lupus erythematosus, lichen planus and graft-versus-host disease-like (GVHD-like) dermatitis. Here, we report the clinical and histopathologic findings in a series of four patients with thymoma-related cutaneous eruptions that showed interface dermatitis without evidence of paraneoplastic pemphigus. Typical of TAMA, cutaneous symptoms developed after thymoma resection and in three patients, heralded residual or recurrent disease. Cutaneous clinical findings were variable and included desquamative erythroderma in two patients, widespread eczematous plaques in another patient, and mucosal erosions accompanying a widespread lichenoid eruption in the last patient. Histopathologic findings in four patients showed either psoriasiform epidermal hyperplasia or epidermal spongiosis with prominent dyskeratosis. Eosinophils were present in varying numbers in the superficial dermal inflammatory infiltrate. The biopsy specimen from the patient with mucosal erosions and lichenoid infiltrate showed a lichenoid interface dermatitis with increased dermal mucin and basement membrane zone thickening, suggestive of connective tissue disease. It is critical for dermatopathologists to recognize the broadening clinical and histologic spectrum of cutaneous TAMA/PAMS, as early diagnosis can expedite the detection of recurrent disease and heighten suspicion for autoimmune involvement of other organ systems.

Financial Disclosure:
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