Abstract:

Paraneoplastic syndromes associated with thymoma most commonly present as myasthenia gravis secondary to autoantibodies to acetylcholine receptors but may also present as thymoma-associated multiorgan autoimmunity (TAMA), pure red cell aplasia due to autoimmune-mediated hypoproliferation of erythrocyte precursors, and hypogammaglobulinemia with pure white blood cell aplasia. TAMA is a newly described rare paraneoplastic disorder presenting similarly to graft-versus-host disease. We report a case of an 82-year-old male with a history of a chronic stable thymoma and acquired immunoglobulin deficiency presenting with erythroderma for two-month duration. Skin biopsies showed interface dermatitis with vacuolar degeneration of the basal layer, necrotic keratinocytes, and mild mononuclear inflammatory infiltrate. The histologic differential diagnosis included graft-versus-host disease, erythema multiforme, connective tissue disease, and drug reaction. Direct immunofluorescence studies were negative for connective tissue disease. Given the negative history of organ transplant, all medications initiated within the last year were discontinued without improvement. During the work up of erythroderma, the patient was hospitalized for multiple episodes of acute anemia requiring multiple units of blood each month. Bone marrow biopsy showed absence of erythroid precursors and B-cells, without presence of abnormal morphology, viral change, neoplasm, or secondary infiltrate, consistent with thymoma-associated paraneoplastic pure red cell aplasia and hypogammaglobulinemia. These findings confirmed suspicion that the skin biopsies were consistent with thymoma antibodies presenting as graft-versus-host disease-like reaction. Systemic glucocorticoid treatment was initiated with significant improvement. This case presents a unique clinical course and histopathological findings consistent with a graft-versus-host disease-like reaction seen in the rare condition of TAMA.

Financial Disclosure:
No current or relevant financial relationships exist.

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Noah Hewitt, BS