Bakr Farrah, Wain E Mary, Wong Sharon, Palmer Roy, Robson Alistair
Department of Dermatology, St John's Institute of Dermatology, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom.
Consultant Dermatologist, HCA UK, London, United Kingdom.
Am J Dermatopathol. 2021 Dec 1;43(12):e190-e196. doi: 10.1097/DAD.0000000000001979.
Primary cutaneous CD4+ small/medium T-cell lymphoproliferative disorder (PCSM-LPD), recently downgraded from a T-cell lymphoma, is a poorly characterized histopathological entity. Presenting as a solitary lesion that often grows rapidly, it may raise suspicion for a cutaneous B-cell lymphoma. However, classically, the dermal lymphoid proliferation is predominantly CD4+ with a follicular T-helper profile and a smaller B-cell fraction. Diagnostic uncertainty may arise when B cells are present in large numbers, a B-cell clone is present, or large cell populations are seen. To meet the diagnostic criterion of PCSM-LPD, large cells should not constitute more than 30% of the infiltrate. The 2 cases presented in this article caused diagnostic uncertainty owing to the observation of high numbers of large cells and in one case the presence of a B-cell clone, on the background of otherwise typical clinicopathological features of PCSM-LPD. We review the literature specifically regarding the prevalence of large cell populations and their immunophenotypic characteristics and in light of this discuss whether a current diagnostic criterion should be reconsidered.
原发性皮肤CD4⁺小/中型T细胞淋巴增殖性疾病（PCSM-LPD），最近从T细胞淋巴瘤降级而来，是一种组织病理学特征尚不明确的实体。它表现为单个病变，通常生长迅速，可能会让人怀疑是皮肤B细胞淋巴瘤。然而，经典情况下，真皮内的淋巴细胞增殖主要为CD4⁺，具有滤泡辅助性T细胞表型，B细胞比例较小。当出现大量B细胞、存在B细胞克隆或可见大细胞群体时，可能会出现诊断不确定性。为符合PCSM-LPD的诊断标准，大细胞不应占浸润细胞的30%以上。本文报道的2例病例，在具有PCSM-LPD典型临床病理特征的背景下，由于观察到大量大细胞，且其中1例存在B细胞克隆，导致诊断存在不确定性。我们专门回顾了有关大细胞群体的患病率及其免疫表型特征的文献，并据此讨论是否应重新考虑当前的诊断标准。
