Nath Vikas, Parks Graham E, Baliga Mithra, Hartle Edgar O, Geisinger Kim R, Shenoy Veena
Department of Pathology, University of Mississippi Medical Center, 2500 North State Street, Jackson, MS, 39216, USA.
Endocr Pathol. 2014 Dec;25(4):427-32. doi: 10.1007/s12022-014-9338-3.
We report two cases of mucoepidermoid carcinoma (MEC) of the thyroid gland coexisting with, and possibly arising in, papillary thyroid carcinoma (PTC). In the first case, CT-guided fine-needle aspiration (FNA) was performed on a paratracheal mass representing extrathyroidal invasion of a right thyroid lobe tumor. The aspirate showed papillary fronds and cells in honeycombed arrangements with fine chromatin, enlarged nuclei, nuclear grooves, and intranuclear inclusions in a background of mucus and blood; a diagnosis of PTC was rendered initially. However, examination of histologic sections of the mass showed nests of malignant squamous cells with interspersed mucous cells and extracellular mucin, concordant with MEC, as well as PTC. A retrospective review of the FNA specimen identified MEC. In the second case, ultrasound-guided FNA was performed on a right thyroid lobe nodule. The aspirate contained two populations of epithelial cells: larger cells showing foci of both squamous and glandular differentiation that were interpreted as MEC and smaller follicular cells with nuclear changes characteristic of PTC; both were addressed in the diagnostic report. Primary MEC of the thyroid is a rare neoplasm typically exhibiting indolent clinical behavior, although our first case demonstrated extensive local invasion. It is thought to arise from squamous metaplasia associated with PTC, Hashimoto thyroiditis, or other inflammatory or neoplastic processes. In thyroid FNAs, the presence of neoplastic mucous cells and extracellular mucin plus malignant squamous cells is diagnostic of MEC. As MEC is thought to arise in PTC, the finding of the latter in these aspiration specimens is not unexpected.
我们报告了两例甲状腺黏液表皮样癌（MEC），它们与甲状腺乳头状癌（PTC）共存，并且可能起源于PTC。在第一例中，对代表右甲状腺叶肿瘤甲状腺外侵犯的气管旁肿块进行了CT引导下细针穿刺抽吸（FNA）。抽吸物显示乳头样结构和呈蜂窝状排列的细胞，染色质细腻，细胞核增大，有核沟，且在黏液和血液背景中有核内包涵体；最初诊断为PTC。然而，对肿块组织切片的检查显示有恶性鳞状细胞巢，其间散在黏液细胞和细胞外黏液，这与MEC以及PTC相符。对FNA标本的回顾性检查发现了MEC。在第二例中，对右甲状腺叶结节进行了超声引导下FNA。抽吸物包含两种上皮细胞群体：较大的细胞显示出鳞状和腺性分化灶，被解释为MEC，较小的滤泡细胞具有PTC特征性的核改变；诊断报告中提及了这两者。甲状腺原发性MEC是一种罕见的肿瘤，通常表现为惰性临床行为，尽管我们的第一例显示有广泛的局部侵犯。它被认为起源于与PTC、桥本甲状腺炎或其他炎症或肿瘤性过程相关的鳞状化生。在甲状腺FNA中，肿瘤性黏液细胞和细胞外黏液以及恶性鳞状细胞的存在可诊断为MEC。由于MEC被认为起源于PTC，在这些抽吸标本中发现PTC并不意外。
