Department of Pathology, Kartal Dr. Lütfi Kirdar City Hospital, University of Health Sciences, Istanbul, Turkey.
Department of Pathology, Koc University, School of Medicine, Istanbul, Turkey.
Acta Cytol. 2022;66(3):244-252. doi: 10.1159/000521134. Epub 2022 Feb 4.
Mucoepidermoid carcinoma (MEC) showing Warthin's tumor (WT)-like features is a low-grade malignancy which should be differentiated from WT. Morphological features may be distinctly different in each case, causing diagnostic difficulties.
Three cases were presented and discussed with their morphologies. All cases that presented with a mass in the parotid gland went to parotidectomy, and all had preoperative fine-needle aspirations (FNAs). Case 1 was a 16-year-old female; FNA was suggestive of WT and initially interpreted as WT histologically. Case 2 was a 27-year-old male; FNA was interpreted as noninformative due to the presence of cyst fluid only. Case 3 was a 53-year-old male and cytologically was found to be suspicious for MEC which contained squamous and goblet cells on a mucoid background. On histopathological examination, case 2 and case 3 were morphologically consistent with low-grade MEC with WT-like features. Prominent lymphoid stroma and the cystic pattern were the characters of these tumors. Case 1 had the classical WT appearance with some mucinous and squamous metaplasia which could only be interpreted as MEC after the detection of MAML2 rearrangement by FISH. The other 2 showed either focal or relatively diffuse usual low-grade MEC findings, and case 3 was also confirmed by MAML2 rearrangement.
Cytological and histopathological features revealed a spectrum. Differentiating WT-like MECs from ordinary WTs may be challenging. On the one end of the spectrum, they may look very much like WT, and on the other end, even though usual MEC features are present, still, WT-like appearance may pose diagnostic difficulty. Showing MAML2 rearrangement in these cases is very helpful. The presence of mucinous and squamous cells in an otherwise WT-like looking tumor should be alarming for MEC, and if possible, each case should be analyzed for MAML2 rearrangement.
具有涎沃辛瘤（WT）样特征的黏液表皮样癌（MEC）是一种低度恶性肿瘤，应与 WT 相鉴别。由于每种情况下的形态特征可能明显不同，因此会导致诊断困难。
呈现了三个病例并讨论了它们的形态。所有表现为腮腺肿块的病例均行腮腺切除术，且所有病例均行术前细针抽吸（FNA）。病例 1 为 16 岁女性；FNA 提示为 WT，最初组织学上也解释为 WT。病例 2 为 27 岁男性；由于仅存在囊液，FNA 被解释为无信息。病例 3 为 53 岁男性，细胞学检查怀疑为 MEC，含有黏液背景下的鳞状和杯状细胞。在组织病理学检查中，病例 2 和病例 3 在形态上与具有 WT 样特征的低级别 MEC 一致。明显的淋巴间质和囊性模式是这些肿瘤的特征。病例 1 具有经典的 WT 外观，伴有一些黏液和鳞状化生，仅在 FISH 检测到 MAML2 重排后才能解释为 MEC。另外 2 例显示为局灶性或相对弥漫性的普通低级别 MEC 表现，且病例 3 也通过 MAML2 重排得到证实。
细胞学和组织病理学特征显示出一个谱系。将具有 WT 样特征的 MEC 与普通 WT 区分开来可能具有挑战性。在谱系的一端，它们可能看起来非常像 WT，而在另一端，即使存在普通 MEC 特征，WT 样外观仍可能导致诊断困难。在这些病例中显示 MAML2 重排非常有帮助。在其他方面表现为 WT 样的肿瘤中出现黏液和鳞状细胞应引起对 MEC 的警惕，如果可能的话，应分析每个病例是否存在 MAML2 重排。
