Primary Cutaneous CD4⁺ Small/Medium T-cell Lymphoproliferative Disorder With T-cell Receptor (TCR) Clonality: The Importance of Clinical Context in Management.

Primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorder (PCSM-TCLPD) is an uncommon, indolent lymphoid proliferation that can resemble more aggressive cutaneous T-cell lymphomas. Recognizing this entity is important to avoid unnecessary workup and treatment. We report a case of PCSM-TCLPD with T-cell receptor (TCR) clonality in a 59-year-old Hispanic female who presented with a six-month history of a slowly enlarging nodule on the left forehead, associated with intermittent pruritus and mild tenderness without bleeding or ulceration. She denied systemic symptoms, including fevers, night sweats, or weight loss. Histopathologic and immunophenotypic findings supported the diagnosis in the appropriate clinical setting. Laboratory studies, imaging, and bone marrow analysis demonstrated no evidence of systemic involvement. Given the lesion's location in a cosmetically sensitive area, care was coordinated with dermatology, hematology/oncology, and plastic surgery. This case highlights the importance of clinicopathologic correlation in distinguishing PCSM-TCLPD from its malignant mimickers and in guiding appropriate management.