Track: Case Reports

Abstract:

Primary cutaneous CD4-positive small/medium-sized pleomorphic T-cell lymphoproliferative disorder (PCSM-LPD) is a rare but recognized entity, representing the second most common form of cutaneous T-cell lymphoproliferative disorders. Histologically, it is characterized by a dermal infiltrate of small to medium-sized CD4+ T-cells. Clinically, it presents as a solitary, asymptomatic cutaneous lesion, most often on the head or neck, with an indolent course and excellent prognosis. We report a case of a 60-year-old female who presented with a solitary lesion on the left central temple. Punch excision revealed dense nodular lymphoproliferation within the dermis without epidermal involvement. The infiltrate was composed predominantly of small to medium-sized lymphocytes with moderate pale cytoplasm, some exhibiting folliculotropism. Immunohistochemistry showed a predominance of CD3+, CD4+, CD5+, and CD43+ T-cells. BCL6 were positive in scattered clusters of lymphoid cells in T-cell rich zones. Ki-67 index was elevated (up to 35%) in T-cell zones, and scattered CD30+ cells were present. Cyclin D1 was negative. PCR-based molecular studies demonstrated a clonal TCR-beta gene rearrangement, with a suspicious TCR-gamma peak suggesting clonality. Based on clinical, histopathologic, immunophenotypic, and molecular features, a diagnosis of PCSM-LPD was rendered. Despite its lymphoma-like features, PCSM-LPD is a benign clonal proliferation, and misclassification as aggressive lymphoma may lead to overtreatment. Recognition of this entity is essential for accurate diagnosis and appropriate management. Presenting this case underscores the importance of raising awareness about this underrecognized disorder and the critical role of clinicopathologic correlation in cutaneous lymphoproliferative conditions.

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Geoffrey Mikita