A 10-year-old female with a several-year history of pityriasis lichenoides (PL) presented with a new, asymptomatic, large, and necrotic ulcer of her right upper arm. Skin biopsy was consistent with lymphomatoid papulosis (LyP) Type D, a recently recognized subtype of LyP that is distinguished histologically by marked epidermotropism and a perivascular infiltrate of medium-sized pleomorphic lymphocytes with a cytotoxic phenotype (CD3+, CD8+). This is only the sixth reported case of LyP Type D in a child, and while the prognosis in children appears favorable, with no reports of progression to lymphoma to date, more experience in children with longer-term follow-up is needed. Our case highlights both the challenging clinical diagnosis, since in our patient the longstanding clinical presentation was indistinguishable from PL, as well as histopathologic diagnosis, which required expert opinion and consensus.

中文翻译：

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儿童淋巴瘤样丘疹病 D 型，一种罕见且具有挑战性的诊断

一名 10 岁女性，有多年苔藓样糠疹 (PL) 病史，右上臂出现新的无症状大坏死性溃疡。皮肤活检与 D 型淋巴瘤样丘疹病 (LyP) 一致，这是一种最近发现的 LyP 亚型，其组织学特征是显着的嗜表皮性和血管周围浸润的中型多形性淋巴细胞，具有细胞毒性表型（CD3+、CD8+）。这只是第六例报告的儿童 D 型 LyP 病例，虽然儿童的预后似乎良好，但迄今为止尚无进展为淋巴瘤的报告，但需要对儿童进行更长期随访的更多经验。我们的案例突出了具有挑战性的临床诊断，因为在我们的患者中，长期的临床表现与 PL 无法区分，