Track: Case Reports

Topic: Lymphoproliferative Disorders

Abstract:

Introduction: Cutaneous pseudolymphoma (CPL) is a benign lymphoproliferative condition that clinically mimics malignant cutaneous lymphomas, such as cutaneous T-cell lymphoma (CTCL). Although most cases of CPL are idiopathic, a few medications have been associated with inducing CPL. Case Presentation: We present a case of a 55-year-old African American female with a history of systemic lupus erythematosus who was seen for the acute development of 5-10 circular to oval plaques scattered on her right flank, right lower abdomen, buttock, and right breast with lesions ranging from 1-5cm in diameter. These lesions developed shortly after completing a course of Trimethoprim-sulfamethoxazole for UTI. A punch biopsy was obtained from a lesion on her right buttock, and results showed sections with atypical lymphocytic infiltrate consistent with a final diagnosis of CTCL. Furthermore, immunohistochemistry revealed a clonal expansion of T-cell population via T-cell receptor, detected gamma gene rearrangement, and positive clonality. At her 3-month follow-up, the patient’s lesions largely resolved after discontinuation of Trimethoprim-sulfamethoxazole and application of topical betamethasone cream. There was no evidence of CTCL on physical exam at this time, so it is likely that the histopathologic changes were due to Trimethoprim-sulfamethoxazole and not a true cutaneous lymphoma given the resolution of lesions with topical steroids and discontinuation of Trimethoprim-sulfamethoxazole. Discussion: This case illustrates an interesting case of Trimethoprim-sulfamethoxazole induced pseudolymphoma, highlighting how even benign reactive cases can have positive clonality. The most important point of treatment in drug-induced pseudolymphoma is to remove the causative agent and avoid re-exposure.

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Natalya Gallaga, MD