Liu Xiaoqin, Liao Xiaoyan, Zhang Dongwei
Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, Rochester, NY, U.S.A.
Cancer Diagn Progn. 2021 Jul 3;1(4):279-283. doi: 10.21873/cdp.10036. eCollection 2021 Sep-Oct.
Carcinoma ex pleomorphic adenoma (PA) of the salivary gland with squamous cell carcinoma (SCC) component is extremely rare and can be easily misdiagnosed as a benign PA or SCC (primary or metastatic).
A 75-year-old male who had no significant past medical history, presented with a rapid growing right parotid gland mass. A fine needle aspiration revealed malignant cells. Following partial parotidectomy, a 2.4 cm ill-defined mass was grossly identified. Microscopically, it showed a keratinizing SCC with adjacent component of residual PA. Immunohistochemically, the malignant tumor cells were positive for p40, p63 and CK5. The residual PA was focally positive for CAM5.2, SMA, p63 and S100. The pathological features were consistent with SCC ex PA. The patient was well at the 7 month-follow-up post-surgery.
SCC ex PA is a rare entity that can be mistaken for a benign PA with squamous metaplasia, or primary or metastatic SCC. It behaves aggressively and has high recurrence and metastasis rate. Awareness of this disease and the diagnostic pitfalls are essential to avoid misinterpretation in difficult cases.
涎腺多形性腺瘤（PA）恶变伴鳞状细胞癌（SCC）成分极为罕见，且极易被误诊为良性PA或SCC（原发性或转移性）。
一名75岁男性，既往无重大病史，因右侧腮腺肿物迅速增大前来就诊。细针穿刺显示存在恶性细胞。行部分腮腺切除术后，大体可见一个2.4 cm边界不清的肿物。显微镜下，可见角化性SCC伴有残留PA的相邻成分。免疫组化显示，恶性肿瘤细胞p40、p63和CK5呈阳性。残留PA局部CAM5.2、SMA、p63和S100呈阳性。病理特征符合PA恶变伴SCC。术后7个月随访时患者情况良好。
PA恶变伴SCC是一种罕见的疾病，可被误诊为伴有鳞状化生的良性PA或原发性或转移性SCC。其行为具有侵袭性，复发和转移率高。认识这种疾病及其诊断陷阱对于避免在疑难病例中出现误诊至关重要。
