Carcinoma showing thymus-like elements (CASTLE) is a rare tumor that commonly occurs in the thyroid gland. Extrathyroidal CASTLE is rarer, and only 11 cases of CASTLE of major salivary glands have been reported to date. We report the first case of amyloid deposition in parotid CASTLE. A 63-year-old man presented with a slowly growing mass in the left parotid region. Computed tomography revealed an approximately 28 × 23 mm mass lesion in the left parotid gland, and squamous cell carcinoma was suspected on biopsy. The patient underwent a parotidectomy with neck dissection. Morphologically, the tumor cells were squamoid and formed nests with lymphoid infiltration. Immunohistochemically, the tumor cells exhibited immunoreactivity for CD5, CD117/c-kit and Bcl-2, p40, and CK5 but not for p16. We diagnosed the tumor as parotid CASTLE. Amyloid deposition was also observed in the primary tumor and metastatic lymph node lesions, which were immunoreactive for cytokeratin 5. Tumor cytokeratin-derived amyloid deposition may be one of characteristics of parotid CASTLE.

中文翻译：

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癌显示胸腺样成分（CASTLE），腮腺内有淀粉样蛋白沉积

显示胸腺样成分的癌（CASTLE）是一种罕见的肿瘤，常见于甲状腺。甲状腺外CASTLE较为罕见，迄今仅报道11例大唾液腺CASTLE。我们报告了第一例腮腺 CASTLE 淀粉样蛋白沉积病例。一名 63 岁男性因左腮腺区域出现缓慢生长的肿块就诊。计算机断层扫描显示左腮腺有一处约 28 × 23 毫米的肿块，活检怀疑鳞状细胞癌。患者接受了腮腺切除术和颈清扫术。形态学上，肿瘤细胞呈鳞状，形成巢状，有淋巴样浸润。免疫组织化学显示，肿瘤细胞对 CD5、CD117/c-kit 和 Bcl-2、p40 和 CK5 表现出免疫反应性，但对 p16 没有免疫反应性。我们诊断肿瘤为腮腺城堡。在原发肿瘤和转移淋巴结病灶中也观察到淀粉样蛋白沉积，这些病灶对细胞角蛋白5呈免疫反应。肿瘤细胞角蛋白衍生的淀粉样蛋白沉积可能是腮腺CASTLE的特征之一。