Abstract：
POU class 2 homeobox 3 (POU2F3)-positive small cell bladder carcinoma (SCBC) is an extremely rare entity, and its clinicopathologic features have not been fully described. Here, we investigated the clinicopathologic features of 4 cases of POU2F3-positive small cell bladder carcinoma (SCBC) and reviewed the literature. We collected 12 cases of SCBC from our departmental archives and detected the expression of POU2F3 by immunohistochemical (IHC) staining. Selected cases with or without POU2F3 expression were subjected to gene expression analysis between two different groups using DESeq2 software. We identified 4 POU2F3-positive SCBC patients, 2 males and 2 females, with a mean age of 77 years. Three patients had hematuria, and 1 patient had dysuria. Radiologic findings showed a bladder mass. Pathologic diagnosis showed that 3 cases were pure SCBC and 1 was mixed urothelial cancer (UC). Histopathologically, four POU2F3-positive SCBC tumors were composed of small round cells with sparse cytoplasm, the nuclei were salt-and-pepper-like or finely granular. Tumor cells showed characteristic cytoplasmic staining with punctate positive signals for cytokeratin. Syn and CD56 were diffusely positive in all the 4 patients. CgA was positive in only one patient. POU2F3-positive SCBC showed higher expression levels of POU2F3, HMGA2 and PLCG2 genes by RNA-Seq. Our data showed the specific clinicopathologic features of 4 rare POU2F3-positive SCBC cases, and the distinct molecular feature was observed between POU2F3-positive and negative SCBC in the limited number of cases.
摘要：
POU2类同源盒3（POU2F3）阳性小细胞膀胱癌（SCBC）是一种极为罕见的实体，其临床病理特征尚未得到充分描述。这里,我们研究了4例POU2F3阳性小细胞膀胱癌（SCBC）的临床病理特征并复习了文献。我们从我科档案中搜集12例SCBC，用免疫组化(IHC)染色检测POU2F3的表达。使用DESeq2软件对具有或不具有POU2F3表达的选定病例进行两个不同组之间的基因表达分析。我们确定了4名POU2F3阳性SCBC患者，2男2女,平均年龄77岁.三个病人有血尿,1例患者出现排尿困难。放射学检查结果显示膀胱肿块。病理诊断为单纯SCBC3例,混合型尿路上皮癌(UC)1例。组织病理学,四个POU2F3阳性的SCBC肿瘤由小圆形细胞组成，细胞质稀疏，核呈盐和胡椒状或颗粒状。肿瘤细胞显示特征性的细胞质染色,具有细胞角蛋白的点状阳性信号。4例患者中Syn和CD56均为弥漫阳性。CgA仅在一名患者中呈阳性。POU2F3阳性SCBC通过RNA-Seq显示POU2F3、HMGA2和PLCG2基因的较高表达水平。我们的数据显示了4例罕见的POU2F3阳性SCBC病例的具体临床病理特征，在有限的病例中，POU2F3阳性和阴性SCBC之间观察到了明显的分子特征。
