Qiu Suimin, Luna Mario A
Department of Surgical Pathology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas, USA.
Head Neck. 2005 Oct;27(10):923-6. doi: 10.1002/hed.20229.
Among salivary glands, the parotid gland is the most common site for secondary neoplastic involvement, and carcinomas and melanomas are the two most common secondary tumors.
We present a case of testicular seminoma metastasizing to the parotid gland. The patient, who had a remote history of testicular seminoma, was initially seen with a parotid mass. A primary parotid lesion was anticipated, and excisional biopsy was performed. The diagnosis of testicular seminoma metastasizing to the parotid gland was established on the basis of histologic findings and was confirmed by immunohistochemical analysis.
Metastatic and primary seminomas have the same morphologic features and cellular composition, and granulomatous reaction is often present in both neoplasms. Extragonadal seminoma often occurs in the midline (presacral, retroperitoneal, anterior mediastinal, and pineal regions); when present in any other locations, the tumor should be considered to be metastatic. Placenta alkaline phosphatase is a useful immunohistochemical stain to confirm the diagnosis, and cytokeratin immunohistonegativity rules out carcinomas or epithelioid sarcomas.
To our knowledge, this is the first published case of metastatic testicular seminoma to the parotid gland. Cytomorphologic features of seminoma and the presence of granulomatous giant cells are important diagnostic clues. Two other neoplasms with granulomatous reactions, nasopharyngeal carcinoma and epithelioid sarcoma, should be considered in the differential diagnosis.
在唾液腺中，腮腺是继发性肿瘤累及最常见的部位，癌和黑色素瘤是两种最常见的继发性肿瘤。
我们报告一例睾丸精原细胞瘤转移至腮腺的病例。该患者有睾丸精原细胞瘤病史，最初因腮腺肿块就诊。预计为原发性腮腺病变，遂行切除活检。根据组织学表现确诊为睾丸精原细胞瘤转移至腮腺，并经免疫组化分析证实。
转移性和原发性精原细胞瘤具有相同的形态学特征和细胞组成，两种肿瘤中常出现肉芽肿反应。性腺外精原细胞瘤常发生于中线部位（骶前、腹膜后、前纵隔和松果体区）；当出现在其他任何部位时，应考虑为转移性肿瘤。胎盘碱性磷酸酶是一种有助于确诊的免疫组化染色，细胞角蛋白免疫组化阴性可排除癌或上皮样肉瘤。
据我们所知，这是首例睾丸精原细胞瘤转移至腮腺的病例报告。精原细胞瘤的细胞形态学特征和肉芽肿巨细胞的存在是重要的诊断线索。鉴别诊断时应考虑另外两种有肉芽肿反应的肿瘤，即鼻咽癌和上皮样肉瘤。
