具有小蓝圆细胞形态的前列腺原发性生殖细胞肿瘤病理学特征

Pathological features of primary extragonadal germ cell tumor of the prostate with small round blue cell morphology

目的探讨原发于前列腺的生殖细胞肿瘤的病理学特征及临床处理方法。方法收集复旦大学附属肿瘤医院2016年1月和9月收治的前列腺原发性生殖细胞肿瘤2例,对其病理学资料、临床处理及随访情况进行回顾性分析。结果患者年龄分别为41岁和32岁,临床表现为下尿路梗阻及排尿不畅症状,影像学提示前列腺巨大占位。前列腺穿刺活检组织学2例肿瘤均表现为小蓝圆细胞形态,浸润性生长,肿瘤背景中夹杂少量小淋巴细胞。免疫组织化学染色提示肿瘤细胞SALL4、OCT3/4、CD117和胎盘碱性磷酸酶(PLAP)标记均为阳性,而前列腺特异性抗原(PSA)、雄激素受体(AR)和突触素均阴性。此外,例1呈现特征性的广谱细胞角蛋白(CKpan)核旁点状阳性模式,可能误诊为上皮来源。体格检查及影像学检查均未查见其他器官肿瘤,综合形态学及免疫组织化学结果,诊断为前列腺原发性精原细胞瘤,随后共进行了6个周期的博来霉素、依托泊苷和顺铂联合化疗,例1随访获得了完全缓解;例2随访肿瘤复发进展且伴肿瘤标志物甲胎蛋白升高,后续根治标本最终诊断为混合性生殖细胞肿瘤。结论前列腺原发性生殖细胞肿瘤罕见,病理学上可表现为小蓝圆细胞形态学特征,合并免疫组织化学CKpan核旁点状阳性染色模式可能成为诊断陷阱。前列腺生殖细胞肿瘤的临床处理策略需结合病理诊断及肿瘤标志物综合评估。

Objective To investigate the clinicopathological features and clinical management of primary extragonadal germ cell tumor of the prostate.Methods Two cases of primary extragonadal germ cell tumor in the prostate were collected at Fudan University Shanghai Cancer Center,in January and September 2016,respectively.Their pathological features,clinical treatments and follow-up were retrospectively analyzed.Results The two patients were 41 and 32 years old,respectively,and both presented with obstructive symptoms of the lower urinary tract.Histologically,both cases showed small round blue cells and an invasive growth pattern.The immunohistochemistry(IHC)stains of SALL4,OCT3/4,CD117 and PLAP were all positive,while those of PSA,AR and syn were negative.Moreover,case 1 demonstrated perinuclear dot-like staining for CKpan,which might be a diagnostic pitfall.There was no evidence of disease in other areas via physical examination or radiographic studies.Based on these IHC findings and the morphology,the two cases were diagnosed as primary seminoma of the prostate,which were consequently treated with six cycles of bleomycin,etoposide and cisplatin-based chemotherapy.A complete response was achieved in case 1.Case 2 was followed up and showed tumor recurrence,and progression with elevated tumor marker AFP.The subsequent radical removed specimens of case 2 were finally diagnosed as mixed germ cell tumor of the prostate.Conclusion As a rare neoplastic entity,primary germ cell tumor of the prostate can show small blue round cell morphology.Pathologically,the morphology of small round blue cells combined with a perinuclear dot-like pattern of CKpan IHC staining may be a diagnostic pitfall.The clinical treatment strategy should be evaluated with consideration of the pathological diagnosis and comprehensive evaluation of the tumor markers.