Athens Veterinary Diagnostic Laboratory, Department of Pathology, College of Veterinary Medicine, University of Georgia, Athens, GA, USA.
Red Oak Animal Hospital, South Fulton, GA, USA.
J Vet Diagn Invest. 2024 Nov;36(6):941-944. doi: 10.1177/10406387241273907. Epub 2024 Aug 20.
A 10-y-old spayed female Staffordshire Terrier dog was evaluated because of a cutaneous left ear base mass. Cytology revealed sheets of cells with anisocytosis and anisokaryosis, round-to-oval or plasmacytoid cytoplasm, and round, central, or eccentric nuclei; binucleate cells were present. Cytologic findings were consistent with a round cell tumor (plasmacytoma or agranular mast cell tumor), amelanotic melanoma, or anaplastic carcinoma. Histologically, neoplastic cells were polygonal to elongate, with round-to-oval nuclei and prominent nucleoli and arranged in sheets and nests on a fibrovascular stroma. Neoplastic cells with plasmacytoid morphology (round, glassy, eosinophilic cytoplasm with eccentric nuclei) were present in ~30% of the neoplasm. There were 18 mitoses in 2.37 mm (10 FN22/40× fields). Neoplastic cells had cytoplasmic immunolabeling for melan A and PNL2 and no immunolabeling for AE3/1 and MUM1, consistent with a dermal melanoma with plasmacytoid differentiation. The patient was re-evaluated ~1 mo after the first biopsy because of local recurrence of the original mass and new masses on the interscapular area and right elbow; these neoplasms were histologically identical to the original submission, plus scattered neoplastic cells in the new masses contained brown cytoplasmic pigment. The dog was euthanized because of swelling and hemorrhage of the tumors and right pelvic limb lameness. Our findings were consistent with a dermal melanoma with plasmacytoid features that were similar to human plasmacytoid melanoma, a rare variant of human melanoma that is diagnostically challenging as it may mimic a plasmacytoma.
一只 10 岁已去势的雌性斯塔福郡斗牛梗犬因左耳基部的皮肤肿块而接受评估。细胞学检查显示细胞呈片状排列，具有大小不等和核异型性，圆形到椭圆形或浆细胞样细胞质，以及圆形、中央或偏心核；存在双核细胞。细胞学检查结果符合圆形细胞瘤（浆细胞瘤或颗粒细胞瘤）、无黑色素性黑色素瘤或间变性癌。组织学上，肿瘤细胞为多角形到长形，具有圆形到椭圆形核和明显的核仁，并排列在纤维血管基质的片层和巢状结构中。约 30%的肿瘤中存在具有浆细胞样形态的肿瘤细胞（圆形、玻璃样、嗜酸性细胞质，偏心核）。在 2.37 mm（10 FN22/40× 视野）中发现 18 个有丝分裂。肿瘤细胞细胞质免疫标记为黑色素 A 和 PNL2，AE3/1 和 MUM1 无免疫标记，符合具有浆细胞样分化的皮肤黑色素瘤。由于最初肿块的局部复发和肩胛区及右肘出现新的肿块，该犬在第一次活检后约 1 个月再次接受评估；这些肿瘤与最初的送检标本在组织学上完全相同，并且新肿块中的散在肿瘤细胞含有棕色细胞质色素。由于肿瘤肿胀和出血以及右后肢跛行，该犬被安乐死。我们的发现与具有浆细胞样特征的皮肤黑色素瘤一致，类似于人类浆细胞样黑色素瘤，这是一种罕见的人类黑色素瘤变体，诊断具有挑战性，因为它可能类似于浆细胞瘤。
