Omman Reeba A, Speiser Jodi, Robinson Shamika, Lapadat Razvan, Mudaliar Kumaran
Department of Pathology, Loyola University Medical Center, Maywood, Illinois.
J Cutan Pathol. 2019 Jun;46(6):411-417. doi: 10.1111/cup.13449. Epub 2019 Apr 3.
At times, distinguishing Bowen disease (BD) and benign seborrheic keratosis (SK) is histologically challenging, especially when SK shows clonal features (clonal seborrheic keratosis [CSK]). While p16 is often reported as positive in BD and negative in SK, p16 expression in CSK is rarely studied. Here we investigate p16 immunohistochemistry in CSK, SK, and BD.
p16 immunohistochemistry with pattern of expression was noted for 14 CSK, 12 SK, and 18 BD. The degree of inflammation among lesions with respect to p16 expression was also noted.
When examining p16 staining in clonal nests of CSK, 57% showed diffuse or patchy/diffuse positivity, 21% showed patchy positivity, and 21% showed clusters of single positive cells. 67% of BD showed diffuse positivity, 11% showed patchy/diffuse positivity, 17% showed patchy positivity, and 6% were negative. 25% of SK showed focal areas of patchy to full thickness positivity, 25% showed moderate number of positive single cells with or without patchy staining, and 50% showed negative/scattered single cell positivity.
Our findings support that p16 positivity limited to clonal nests in CSK is normal. p16 positivity in clonal nests of CSK in isolation without concurrent atypical histologic features should not be used to support a diagnosis of BD.
有时，在组织学上区分鲍温病（BD）和良性脂溢性角化病（SK）具有挑战性，尤其是当SK表现出克隆性特征时（克隆性脂溢性角化病[CSK]）。虽然p16在BD中通常呈阳性，而在SK中呈阴性，但很少研究CSK中的p16表达。在此，我们研究CSK、SK和BD中的p16免疫组化情况。
对14例CSK、12例SK和18例BD进行p16免疫组化并记录其表达模式。还记录了病变中与p16表达相关的炎症程度。
在检查CSK的克隆巢中的p16染色时，57%表现为弥漫性或斑片状/弥漫性阳性，21%表现为斑片状阳性，21%表现为单个阳性细胞簇。67%的BD表现为弥漫性阳性，11%表现为斑片状/弥漫性阳性，17%表现为斑片状阳性，6%为阴性。25%的SK表现为斑片状至全层阳性的局灶区域，25%表现为中等数量的阳性单个细胞，有或无斑片状染色，50%表现为阴性/散在单个细胞阳性。
我们的研究结果支持CSK中仅限于克隆巢的p16阳性是正常的。孤立的CSK克隆巢中p16阳性，若无并发的非典型组织学特征，不应作为支持BD诊断的依据。
