DUSP22-rearranged primary cutaneous anaplastic large-cell lymphoma (pcALCL) has a biphasic histological pattern defined by large dermal atypical lymphocytes and epidermotropic small lymphocytes resembling pagetoid reticulosis, but the positivity rate of the biphasic pattern in DUSP22-rearranged pcALCL is unknown. Immunohistochemically, LEF1 expression in >75% of tumor cells is associated with DUSP22-rearrangement (DUSP22-R) in systemic ALCL. However, whether this association applies to pcALCL remains unclear. To analyze these pathological clues for screening DUSP22-R, we reviewed 11 skin biopsies from three patients with DUSP22-rearranged pcALCL. All specimens showed a biphasic pattern, of which three showed nonpagetoid infiltration of the epidermis. In all lesions, small-cell changes of tumor cells were observed not only within the epidermis but also under the epidermis. LEF1 positivity rates varied by lesion (range: 30%–90%, mean: 59.6%) with only three patients expressing LEF1 in more than 75% of tumor cells. In conclusion, the biphasic pattern was a constant finding in DUSP22-rearranged pcALCL, but it was not always pagetoid reticulosis-like. The recognition of small-cell change outside the epidermis may be helpful in diagnosing DUSP22-rearranged pcALCL. However, LEF1 expression was variable and its diagnostic usefulness may be limited.

中文翻译：

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DUSP22 重排的原发性皮肤间变性大细胞淋巴瘤中恒定的小细胞变化和可变的 LEF1 表达：三名患者的重复活检分析

DUSP22重排的原发性皮肤间变性大细胞淋巴瘤（pcALCL）具有由大真皮非典型淋巴细胞和亲表皮性小淋巴细胞定义的双相组织学模式，类似于佩吉样网织组织病，但DUSP22重排的pcALCL中双相模式的阳性率尚不清楚。免疫组织化学显示，>75% 的肿瘤细胞中 LEF1 表达与系统性 ALCL 中的DUSP22重排 ( DUSP22 -R)相关。然而，这种关联是否适用于 pcALCL 仍不清楚。为了分析这些病理线索以筛查DUSP22 -R，我们回顾了三名DUSP22重排 pcALCL患者的 11 份皮肤活检组织。所有标本均显示双相模式，其中三个显示表皮的非页状浸润。在所有病灶中，不仅在表皮内而且在表皮下均观察到肿瘤细胞的小细胞变化。LEF1 阳性率因病变而异（范围：30%–90%，平均值：59.6%），只有 3 名患者在超过 75% 的肿瘤细胞中表达 LEF1。总之，双相模式在DUSP22重排的 pcALCL中经常出现，但并不总是类似佩吉样网状组织增生。识别表皮外的小细胞变化可能有助于诊断DUSP22重排的 pcALCL。然而，LEF1 表达是可变的，其诊断用途可能有限。