Furihata Kaoru, Iwashita Waka, Kurabayashi Atsushi, Koji Kojima, Furihata Mutsuo
Department of Pathology, Kochi Medical School, Kochi University, Nankoku, Kochi, Japan.
Department of Gastroenterology, Division of Internal Medicine, Tosa Municipal Hospital, Tosa, Kochi, Japan.
Pathol Int. 2025 Jun;75(6):310-314. doi: 10.1111/pin.70014. Epub 2025 Apr 14.
This study presents the ultrastructural and immunohistochemical findings of a gastric bizarre leiomyoma arising in the vestibule of a 79-year-old male. Histologically, loosely proliferating tumor cells consist of large, multinucleated, bizarre nuclei with intranuclear inclusions and abundant cytoplasm-containing vacuoles. A murky line was apparent between the tumor cells and eosinophilic and heterogenous stroma-like areas. Immunohistochemically, tumor cells exhibited positively stained dot patterns of α-smooth muscle actin and caldesmon, which were distributed in the cytoplasm of tumor cells and stroma-like regions. Ultrastructurally, tumor cells exhibited extended and complex cytoplasmic processes comprising the fascicles of filamentous fibers. These structures were also detected in the apparent stroma-like regions observed histologically and were consistent with the α-smooth muscle actin- and caldesmon-immunopositive dot structures. The original stromal areas remained as considerably narrow gaps between tumor cells with extended cytoplasmic processes. To the best of our knowledge, this is the first report detailing the unique ultrastructural and immunohistochemical characteristics of tumor cells and the limited stromal composition of an extremely rare primary gastric bizarre leiomyoma.
本研究展示了一名79岁男性胃前庭发生的奇异型平滑肌瘤的超微结构和免疫组化结果。组织学上，肿瘤细胞呈松散增殖，由具有核内包涵体的大的、多核的、奇异核以及含有丰富空泡的细胞质组成。肿瘤细胞与嗜酸性且异质性的基质样区域之间可见一条模糊的界限。免疫组化方面，肿瘤细胞呈现α-平滑肌肌动蛋白和钙调蛋白阳性染色的点状模式，分布于肿瘤细胞和基质样区域的细胞质中。超微结构上，肿瘤细胞呈现出由丝状纤维束组成的延伸且复杂的细胞质突起。这些结构在组织学观察到的明显基质样区域也被检测到，并且与α-平滑肌肌动蛋白和钙调蛋白免疫阳性的点状结构一致。原始基质区域在具有延伸细胞质突起的肿瘤细胞之间保留为相当狭窄的间隙。据我们所知，这是第一份详细描述极罕见的原发性胃奇异型平滑肌瘤肿瘤细胞独特的超微结构和免疫组化特征以及有限的基质组成的报告。
