Panse Gauri, McNiff Jennifer M, Ko Christine J
Dermatopathology Division, Department of Dermatology, Yale School of Medicine, New Haven, Connecticut.
J Cutan Pathol. 2017 Jun;44(6):553-556. doi: 10.1111/cup.12950.
Basal cell carcinoma (BCC) can resemble Merkel cell carcinoma (MCC) on histopathological examination and while CK20 is a useful marker in this differential, it is occasionally negative in MCC. CD56, a sensitive marker of neuroendocrine differentiation, is sometimes used to identify MCC, but has been reportedly variably positive in BCC as well. In contrast, CK5/6 consistently labels BCC but is not expressed in neuroendocrine tumors.
We evaluated 20 cases of BCC for the pattern of CD56 and cytokeratin 5/6 (CK5/6) staining, hypothesizing that these 2 stains could differentiate BCC from MCC in difficult cases. Seventeen cases of MCC previously stained with CD56 were also examined.
All BCCs showed patchy expression of CD56 except for 2 cases, which showed staining of greater than 70% of tumor. CK5/6 was diffusely positive in all cases of BCC. Fifteen of 17 MCCs were diffusely positive for CD56. The difference in the pattern of CD56 expression between MCC and BCC (diffuse vs patchy, respectively) was statistically significant (P < .05).
BCC typically shows patchy CD56 expression and diffuse CK5/6 positivity. These 2 markers can be used to distinguish between BCC and MCC in challenging cases.
在组织病理学检查中，基底细胞癌（BCC）可能类似于默克尔细胞癌（MCC），虽然细胞角蛋白20（CK20）是这种鉴别诊断中的有用标志物，但它在MCC中偶尔呈阴性。CD56是神经内分泌分化的敏感标志物，有时用于识别MCC，但据报道在BCC中也有不同程度的阳性表现。相比之下，CK5/6始终标记BCC，但在神经内分泌肿瘤中不表达。
我们评估了20例BCC的CD56和细胞角蛋白5/6（CK5/6）染色模式，假设这两种染色可在疑难病例中区分BCC和MCC。还检查了17例先前用CD56染色的MCC。
除2例肿瘤染色大于70%的病例外，所有BCC均显示CD56的斑片状表达。CK5/6在所有BCC病例中均呈弥漫性阳性。17例MCC中有15例CD56弥漫性阳性。MCC和BCC之间CD56表达模式的差异（分别为弥漫性和斑片状）具有统计学意义（P <.05）。
BCC通常显示斑片状CD56表达和弥漫性CK5/6阳性。这两种标志物可用于在疑难病例中区分BCC和MCC。
