Delgado R, Klimstra D, Albores-Saavedra J
Department of Pathology, University of Texas Southwestern Medical Center, Dallas 75235-9072, USA.
Cancer. 1996 Sep 1;78(5):958-67. doi: 10.1002/(SICI)1097-0142(19960901)78:5<958::AID-CNCR4>3.0.CO;2-8.
Salivary duct carcinoma (SDC) has been established as a morphologically distinct and highly aggressive (HG) malignancy of the major salivary glands. However, a low grade (LG) or intermediate grade salivary duct neoplasm has not been described.
We report the clinicopathologic findings of 10 cases believed to represent the (LG) counterpart of SDC. Immunoperoxidase stains were performed on five cases, and electron microscopy on three.
All of the tumors occurred in adult patients with no sex predilection, and presented as slow growing parotid gland lesions. Four cases involved the superficial lobe, one the deep lobe, and one arose within an intraparotid lymph node. The exact location of the tumor within the parotid gland was not stated in four cases. The size of the tumors ranged from 0.7 to 4 cm in greatest dimension, with most measuring between 1 and 2 cm. The gross appearance was focally to predominantly cystic. Microscopically, the tumors were characterized by intraductal proliferative lesions exhibiting three main patterns: (1) cystic ducts with micropapillary, tufted, and plaque-like intraluminal projections; (2) ducts distended by a solid or pseudocribriform (fenestrated) cellular proliferation, with varied cystic dilatation; and (3) ducts exhibiting architectural atypia. The three patterns coexisted and merged in most tumors, in varying proportions. All tumors shared bland to LG cytologic features, with the exception of one that had focal high-grade cytologic ductal atypia. Despite gross circumscription, there was microscopic multifocality, and in one case, stromal invasion. By immunohistochemistry, the neoplastic cells expressed the conventional ductal and glandular epithelial cell markers in addition to strong positivity for S-100 with coexpression for CK-903. Electron microscopy confirmed the ductal phenotype of the tumors and supported an in situ process evidenced by the presence of native myoepithelial cells. Nine patients underwent total parotidectomy and one superficial parotidectomy. One patient received radiation therapy following total parotidectomy. Follow-up for 6 cases ranged from 2 to 12 years and revealed no evidence of disease.
LG-SDC represents the LG end of the spectrum of salivary duct malignant neoplasms and exhibits differentiation towards an intercalated duct-like cell phenotype. Its relationship to HG-SDC should be further explored.
涎腺导管癌（SDC）已被确认为一种形态学上独特且侵袭性很强的（高级别，HG）大涎腺恶性肿瘤。然而，低级别（LG）或中级别涎腺导管肿瘤尚未见报道。
我们报告了10例被认为代表SDC低级别对应物的临床病理特征。对其中5例进行了免疫过氧化物酶染色，3例进行了电子显微镜检查。
所有肿瘤均发生于成年患者，无性别倾向，表现为生长缓慢的腮腺病变。4例累及浅叶，1例累及深叶，1例起源于腮腺内淋巴结。4例未说明肿瘤在腮腺内的确切位置。肿瘤最大径范围为0.7至4 cm，多数在1至2 cm之间。大体外观以局灶性至主要为囊性为主。显微镜下，肿瘤的特征为导管内增殖性病变，呈现三种主要模式：（1）具有微乳头、簇状和斑块状腔内突起的囊性导管；（2）被实性或假筛状（有窗孔的）细胞增殖扩张的导管，伴有不同程度的囊性扩张；（3）表现出结构异型性的导管。这三种模式在大多数肿瘤中以不同比例共存并相互融合。除1例有局灶性高级别细胞学导管异型性外，所有肿瘤均具有温和至低级别细胞学特征。尽管大体上边界清楚，但显微镜下呈多灶性，1例有间质浸润。免疫组化显示，肿瘤细胞除了对S-100呈强阳性且与CK-903共表达外，还表达传统的导管和腺上皮细胞标志物。电子显微镜证实了肿瘤的导管表型，并支持原位过程，表现为存在天然肌上皮细胞。9例患者接受了全腮腺切除术，1例接受了浅叶腮腺切除术。1例患者在全腮腺切除术后接受了放疗。6例患者的随访时间为2至12年，未发现疾病复发迹象。
低级别涎腺导管癌代表涎腺导管恶性肿瘤谱系中的低级别末端，表现出向闰管样细胞表型的分化。其与高级别涎腺导管癌的关系应进一步探讨。
