Zhang Lingxin, Yang Chen, Lewis James S, El-Mofty Samir K, Chernock Rebecca D
Department of Pathology and Immunology, Washington University School of Medicine, St Louis, MO 63110, USA.
Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, TN 37232, USA; Department of Otolaryngology, Vanderbilt University Medical Center, Nashville, TN 37232, USA.
Hum Pathol. 2017 Aug;66:40-47. doi: 10.1016/j.humpath.2017.05.019. Epub 2017 May 26.
Follicular dendritic cell sarcoma is a rare mesenchymal neoplasm that most commonly occurs in cervical lymph nodes. It has histologic and clinical overlap with the much more common p16-positive human papillomavirus (HPV)-related squamous cell carcinoma of the oropharynx, which characteristically has nonkeratinizing morphology and often presents as an isolated neck mass. Not surprisingly, follicular dendritic cell sarcomas are commonly misdiagnosed as squamous cell carcinoma. Immunohistochemistry is helpful in separating the 2 entities. Follicular dendritic cell sarcoma expresses dendritic markers such as CD21 and CD23 and is almost always cytokeratin negative. However, in many cases of HPV-related oropharyngeal carcinoma, only p16 immunohistochemistry as a prognostic and surrogate marker for HPV is performed. p16 expression in follicular dendritic cell sarcoma has not been characterized. Here, we investigate the expression of p16 in follicular dendritic cell sarcoma and correlate it with retinoblastoma protein expression. A pilot study of dendritic marker expression in HPV-related oropharyngeal squamous cell carcinoma was also performed. We found that 4 of 8 sarcomas expressed p16 with strong and diffuse staining in 2 cases. In 2 of the 4 cases, p16 expression corresponded to loss of retinoblastoma protein expression. Dendritic marker expression (CD21 and CD23) was not found in HPV-related oropharyngeal squamous cell carcinomas. As such, positive p16 immunohistochemistry cannot be used as supportive evidence for the diagnosis of squamous cell carcinoma as strong and diffuse p16 expression may also occur in follicular dendritic cell sarcoma. Cytokeratins and dendritic markers are critical in separating the two tumor types.
滤泡树突状细胞肉瘤是一种罕见的间叶性肿瘤，最常发生于颈部淋巴结。它在组织学和临床上与更为常见的p16阳性人乳头瘤病毒（HPV）相关的口咽鳞状细胞癌存在重叠，后者具有非角化形态特征，且常表现为孤立的颈部肿块。不出所料，滤泡树突状细胞肉瘤常被误诊为鳞状细胞癌。免疫组织化学有助于区分这两种实体。滤泡树突状细胞肉瘤表达树突状细胞标志物如CD21和CD23，且几乎总是细胞角蛋白阴性。然而，在许多HPV相关的口咽癌病例中，仅进行p16免疫组织化学检测作为HPV的预后和替代标志物。滤泡树突状细胞肉瘤中p16的表达尚未得到明确描述。在此，我们研究了p16在滤泡树突状细胞肉瘤中的表达，并将其与视网膜母细胞瘤蛋白表达相关联。我们还对HPV相关的口咽鳞状细胞癌中的树突状细胞标志物表达进行了一项初步研究。我们发现8例肉瘤中有4例表达p16，其中2例呈强弥漫性染色。在这4例中的2例中，p16表达与视网膜母细胞瘤蛋白表达缺失相对应。在HPV相关的口咽鳞状细胞癌中未发现树突状细胞标志物（CD21和CD23）表达。因此，p16免疫组织化学阳性不能作为支持鳞状细胞癌诊断的证据，因为强弥漫性p16表达也可能出现在滤泡树突状细胞肉瘤中。细胞角蛋白和树突状细胞标志物对于区分这两种肿瘤类型至关重要。
