Cutaneous leiomyosarcomas are malignant mesenchymal tumors of smooth muscle origin and are reported occasionally in avian species. A 14-y-old male laboratory White Carneau pigeon (Columba livia) was presented for surgical excision of a cervical soft tissue mass. Ultrasonography with color flow Doppler imaging revealed multiple cavitations of mixed echogenicity within the mass and vascularization. Histologically, the dermis and subcutis were expanded by a densely cellular multinodular mass comprised of fusiform cells forming haphazardly arranged broad streams and short interwoven bundles, often surrounding blood vessels and variably sized cavitations. Neoplastic cells were strongly immunopositive for desmin and α–smooth muscle actin, and negative for pancytokeratin, S100, and von Willebrand factor. Based on histopathology and IHC findings, the cutaneous mass was diagnosed as leiomyosarcoma (LMS). The pigeon died 312 d post-operatively. Postmortem examination revealed masses infiltrating the left and right pulmonary airways and one hepatic nodule, but no regrowth at the surgical site. Histologic and IHC evaluation of the pulmonary and hepatic masses were consistent with LMS, representing metastatic foci from the primary cutaneous LMS. Our case highlights the malignant behavior and histomorphologic features of cutaneous LMS in an avian species.

皮肤平滑肌肉瘤是平滑肌来源的恶性间叶性肿瘤，偶尔有鸟类报道。一只 14 岁雄性实验室白卡诺鸽 ( Columba livia ) 接受手术切除颈部软组织肿块。彩色血流多普勒成像超声检查显示肿块和血管内存在多个混合回声空泡。在组织学上，真皮和皮下组织被致密的细胞多结节团块扩张，该团块由梭形细胞组成，形成随意排列的宽流和短交织束，通常围绕血管和大小不一的空洞。肿瘤细胞对结蛋白和 α-平滑肌肌动蛋白呈强免疫阳性，对全细胞角蛋白、S100 和冯维勒布兰德因子呈阴性。根据组织病理学和 IHC 结果，皮肤肿块被诊断为平滑肌肉瘤 (LMS)。鸽子术后312天死亡。尸检发现左右肺气道有肿块浸润，还有一个肝结节，但手术部位没有再生长。肺部和肝脏肿块的组织学和 IHC 评估与 LMS 一致，代表来自原发皮肤 LMS 的转移灶。我们的病例强调了鸟类皮肤 LMS 的恶性行为和组织形态学特征。