Department of Dermatology, Xijing Hospital, The Fourth Military Medical University, Xian, China.
Department of Dermatology, Huashan Hospital, Fudan University, Shanghai, China.
J Cutan Pathol. 2023 Dec;50(12):1094-1098. doi: 10.1111/cup.14514. Epub 2023 Aug 19.
Onychomatricoma is a nail neoplasm that usually presents as longitudinal nail plate thickening, involving either the partial or whole nail. Histopathologically, it is characterized by deep invaginations of the proliferating nail matrix and proliferation of CD34+ and CD10+ spindle cells with collagenous to myxoid stroma. Onychomatricoma has been considered a fibroepithelial neoplasm. Recently, RB1 loss has been verified using array comparative genomic hybridization.
This study investigated the RB1 status in onychomatricoma with morphological methods.
Six patients with onychomatricoma were included in the study. RB1 status was assessed using immunohistochemical staining and fluorescence in situ hybridization. Immunohistochemical staining showed that all six cases experienced RB1 loss in the mesenchymal component of onychomatricoma but not in the proliferated nail matrix. Fluorescence in situ hybridization in five cases showed a monoallelic deletion of the RB1 locus in the mesenchymal component but not in the proliferated nail matrix.
RB1 loss was observed only in the mesenchymal component of onychomatricoma. Our findings suggest that the proliferated nail matrix in onychomatricoma represents reactive hyperplasia of various degrees secondary to neoplastic mesenchymal proliferation. This indicates that onychomatricoma should be recognized as an RB1-deleted soft tissue neoplasm rather than a fibroepithelial neoplasm.
甲床瘤是一种甲下肿瘤，通常表现为纵向甲板增厚，累及部分或整个甲板。组织病理学上，其特征为增生的甲母质深内陷和 CD34+和 CD10+梭形细胞增生，伴有胶原样至黏液样基质。甲床瘤被认为是一种纤维上皮性肿瘤。最近，使用阵列比较基因组杂交技术证实了 RB1 缺失。
本研究采用形态学方法研究了甲床瘤中的 RB1 状态。
本研究纳入了 6 例甲床瘤患者。采用免疫组织化学染色和荧光原位杂交检测 RB1 状态。免疫组织化学染色显示，所有 6 例甲床瘤的间充质成分均存在 RB1 缺失，但增生的甲母质中不存在 RB1 缺失。5 例荧光原位杂交显示，间充质成分中存在 RB1 基因座的单等位基因缺失，但增生的甲母质中不存在。
仅在甲床瘤的间充质成分中观察到 RB1 缺失。我们的研究结果表明，甲床瘤中增生的甲母质是肿瘤性间充质增殖引起的不同程度的反应性增生。这表明甲床瘤应被认为是一种 RB1 缺失的软组织肿瘤，而不是纤维上皮性肿瘤。
