Department of Pathology, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
Department of Genomic Medicine, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA.
J Cutan Pathol. 2022 Sep;49(9):802-807. doi: 10.1111/cup.14262. Epub 2022 Jun 10.
:NCOAx-rearranged fibroblastic tumor is a recently described, morphologically distinctive subcutaneous fibroblastic tumor with benign behavior. To date, 12 cases have been reported. Here, we report a new case of PRRX::NCOAx-rearranged fibroblastic tumor showing a prominent pigmented component. The lesion occurred on the shoulder of a 23-year-old male. It was an at least 2.5 cm subcutaneous tumor with a multinodular and plexiform appearance. Morphologically, the tumor was characterized by a variably cellular proliferation of uniform oval to spindle cells arranged in fascicles and cords within a myxocollagenous stroma. Irregular, elongated, dilated vessels were prominent at the periphery of tumor nodules. In addition, nests and clusters of pigment-laden epithelioid and dendritic cells were present. Immunohistochemically, the non-pigmented tumor cells showed patchy positivity for factor XIIIa and focal positivity for S100 protein. The pigmented cells were positive for S100 protein, SOX10, MITF, and a pan-melanocytic cocktail (Melan-A, HMB-45, and tyrosinase). Next-generation RNA sequencing identified an in-frame PRRX1::NCOA1 fusion. In summary, this case highlights a rare pigmented variant of PRRX::NCOAx-rearranged fibroblastic tumor, expanding the morphologic spectrum of this newly described mesenchymal tumor.
:NCOAx 重排型纤维母细胞性肿瘤是一种新近描述的具有独特形态学特征的皮下纤维母细胞性肿瘤，具有良性行为。迄今为止，已有 12 例报道。在此，我们报告 1 例新的 PRRX::NCOAx 重排型纤维母细胞性肿瘤，其表现出显著的色素成分。病变发生于 23 岁男性的肩部。这是一个至少 2.5 厘米的皮下肿瘤，具有多结节和丛状外观。形态上，肿瘤的特征是在黏液样胶原基质中排列成束状和条索状的均匀椭圆形至梭形细胞呈不同程度的细胞增生。不规则、伸长的扩张血管在肿瘤结节的外围很突出。此外，还存在色素沉着的上皮样和树突状细胞巢和簇。免疫组化染色显示，非色素性肿瘤细胞呈斑驳阳性表达 for factor XIIIa，局灶性阳性表达 S100 蛋白。色素性细胞阳性表达 S100 蛋白、SOX10、MITF 和泛黑色素细胞鸡尾酒（Melan-A、HMB-45 和酪氨酸酶）。下一代 RNA 测序鉴定出一个框架内的 PRRX1::NCOA1 融合。总之，本病例突出了 PRRX::NCOAx 重排型纤维母细胞性肿瘤的一种罕见的色素变体，扩展了这种新描述的间叶性肿瘤的形态学谱。
