化生性胸腺瘤2例临床病理分析

目的：探讨化生性胸腺瘤的临床及病理学特征。方法：应用光镜及免疫组织化学方法观察2例化生性胸腺瘤的组织学特点及免疫学表型,并复习相关文献。结果：2例均为男性,年龄55岁及56岁。组织学肿瘤显示双相分化特点,上皮细胞区域与梭形细胞区域交错分布并相互移行。上皮细胞呈相互吻合的束状、岛状及宽大的梁状排列,细胞轻度异型,可见核沟及核内假包涵体,偶见核分裂像;梭形细胞呈短束状或席纹状排列,细胞温和,未见核分裂像。免疫表型：上皮细胞区域CK19和AE1/AE3呈强阳性表达,上皮膜抗原（epithelial membrane antigen,EMA）弱阳性;梭形细胞区域表达Vimentin、Bcl-2及CD99,AE1/AE3局灶阳性,EMA弱阳性。两种区域中Ki67指数均〈5%。间质淋巴细胞CD3、CD5、CD20阳性,不表达Td T和CD99。结论：化生性胸腺瘤是一种罕见的良性或低度恶性胸腺肿瘤,诊断依靠病理组织学和免疫组织化学标记,完整切除预后良好。     

化生性胸腺瘤1例报道并文献复习

目的探讨化生性胸腺瘤(metaplastic thymoma)的临床与病理学特点。方法对1例少见的化生性胸腺瘤进行光镜下组织学检查,同时进行免疫组化标记CK(AE1/AE3)、vimentin、CD99、TdT、CD99、CD3、CD5、CD20、CD34、CD43、CD57、calretinin、VEGF及Ki-67,并复习相关文献。结果患者女性4,5岁,左侧纵隔有一包膜完整的肿块,组织学特征具有明显双相性分化的肿瘤,由互相盘绕的上皮岛和束状梭形细胞组成,并可见出血囊性变的区域。免疫组化染色上皮细胞区域:CK(AE1/AE3)强阳性,vimentin阴性;梭形细胞区域:vimentin弥漫阳性,CK(AE1/AE3)及EMA阴性,Ki-67增殖指数1%;间质淋巴细胞:CD3、CD5、CD20、CD43均阳性,TdT和CD99均阴性。结论化生性胸腺瘤是一种少见的交界性或低度恶性的肿瘤,根据组织学特征及免疫组化检测可做出明确诊断。     

化生性胸腺瘤5例临床病理分析

目的探讨化生性胸腺瘤(metaplastic thymoma,MT)的临床病理特点、免疫表型、诊断、鉴别诊断及预后。方法收集5例MT的临床病理资料行光镜观察及免疫组化染色,并复习相关文献。结果患者女性4例,男性1例,平均年龄49. 2岁。临床均表现为前纵隔肿块,肿瘤最大径6. 5～12. 0 cm,界限清楚或有包膜,切面呈均质、实性,质韧,灰白、灰黄色。镜下肿瘤显示双相分化特点,上皮细胞与梭形细胞交错分布并相互移行。上皮细胞呈岛状排列并相互吻合,细胞轻度异型,可见核沟和核内假包涵体;梭形细胞形态温和,呈束状排列;两种类型细胞中核分裂象均罕见。免疫表型:上皮细胞CK(AE1/AE3)呈强阳性,EMA呈灶阳性,CD20呈阴性,Ki-67增殖指数为1%～4%;梭形细胞vimentin呈弥漫阳性,EMA呈弱阳性,CD20呈阴性;间质淋巴细胞CD3呈阳性,Td T呈阴性。患者均无重症肌无力,术后无复发和转移。结论 MT是一种罕见的低度恶性的胸腺肿瘤,其独特的双相性组织学特征及免疫表型有助于诊断和鉴别诊断。     

异位错构瘤性胸腺瘤的临床病理学观察和免疫组织化学研究

目的探讨异位错构瘤性胸腺瘤的临床病理学特征、免疫学表型和组织发生。方法对2例异位错构瘤性胸腺瘤进行临床病理学分析,采用免疫组织化学LSAB法行AE1/AE3、细胞角蛋白(CK)5、CK7、CK8、CK20、上皮膜抗原(EMA)、波形蛋白、CD5、CD10、α-平滑肌肌动蛋白(SMA)、calponin、结蛋白、CD34、S-100蛋白、CD57、胶质纤维酸性蛋白(GFAP)、甲状腺转录因子(TTF)-1和CD99标记。结果两例均发生于男性,年龄分别为20岁和40岁,因发现胸骨柄上缘肿块6个月和左锁骨上肿块2个多月就诊。肿块呈球形和卵圆形,边界清楚,最大直径分别为5cm和3cm,切面呈灰白色,质地柔软。组织学上,肿瘤由梭形细胞、上皮细胞和成熟的脂肪细胞3种成分混合组成。梭形细胞成分在2例中分别占到85%和70%,形态上类似纤维母细胞,多呈束状、编织状或席纹状排列。上皮细胞成分在两例中均占10%左右,形态上以非角化性鳞状上皮为主,可呈实性的小岛屿状、类似造釉细胞瘤的条索状和扩张的囊肿样排列,部分区域显示腺样分化,可见腺管形成。上皮细胞和梭形细胞在形态上有移行。成熟的脂肪组织呈不规则性分布,在两例肿瘤中所占的比例分别为<5%和20%。免疫组织化学标记显示,上皮细胞表达AE1/AE3、CK5、CK7、CK8和EMA,梭形细胞除CK外还表达波形蛋白、CD10和CD34,并部分表达α-SMA和calponin。两种细胞成分均不表达CK20、CD5、TTF-1、结蛋白、S-100蛋白、CD57、GFAP和CD99。结论异位错构瘤性胸腺瘤是一种好发于中青年男性锁骨上和胸锁关节附近软组织内的良性肿瘤,是一种由上皮和肌上皮组成的混合性肿瘤,可能起自于His颈窦,采用鳃原基混合瘤来命名或许更为合适。     

原发性肾脏滑膜肉瘤临床病理及分子遗传学分析

目的探讨原发性肾脏滑膜肉瘤的临床病理特征、诊断及鉴别诊断。方法对1例罕见的原发性肾脏滑膜肉瘤进行光镜观察和免疫组化染色,并用RT-PCR方法在石蜡包埋组织中检测SYT-SSX融合mRNA表达,结合文献分析讨论。结果肿瘤由核分裂活跃的单形的梭形细胞组成,呈交织的束状或实性排列,部分区域呈血管外皮瘤样图像,未见上皮分化成分;囊性区囊内衬核分裂不活跃的多边形的鞋钉样上皮。免疫表型瘤细胞vimentin、CD99、bcl-2、S-100均阳性,Ki-67强阳性;CK(AE1/AE3)、EMA、SMA、CD117、CD34、p53、ER、PR均阴性。RT-PCR方法检测到肿瘤组织中有SYT-SSXmRNA表达,对照组SYT-SSX无表达。患者术后5月内死亡。结论原发性肾脏滑膜肉瘤罕见,需要与肾脏其他一些梭形细胞肿瘤相鉴别,分子遗传学检测SYT-SSX融合mRNA有助于其诊断和鉴别诊断。     

伴有神经内分泌分化的乳腺梭形细胞癌

目的探讨乳腺伴有神经内分泌分化的梭形细胞癌的病理形态学和免疫表型特点及鉴别诊断。方法复习2500例乳腺癌切片,找出以梭形细胞占主要优势（〉80％）的癌5例,其中2例梭形细胞型导管内癌和3例梭形细胞型浸润癌。采用HE、阿辛蓝（AB）／PAS和网织染色,以及用癌胚抗原（CEA）、上皮膜抗原（EMA）、细胞角蛋白（CK7、3413E12、AE1／AE3）、神经元特异性烯醇化酶（NSE）、突触素、嗜铬蛋白（cg）A、Lue-7、波形蛋白,S-100、平滑肌肌动蛋白（SMA）、calponin、雌激素受体（ER）、孕激素受体（PR）、c—erbB-2、E-钙黏素、Ki-67、p53抗体进行免疫组织化学观察。其中4例有随访信息。结果患者平均年龄在68岁。镜下：5例癌细胞形态主要为长梭形的上皮样细胞,3例有少数胞质内空泡状细胞,4例可见散在AB阳性细胞。免疫组织化学5例均表达AE1／AE3、EMA、CEA、E-钙黏素和突触素,CK7有4例表达,NSE阳性3例,CgA和Lue7阳性2例,ER阳性4例,PR阳性2例,1例表达c-erbB-2,1例有灶状波形蛋白阳性。免疫组织化学结果显示2例梭形细胞型导管内癌和1例梭形细胞型浸润性癌是梭形细胞型的神经内分泌癌,另外2例梭形细胞型浸润性癌是伴有神经内分泌分化的化生性癌。随访3例存活（24～58个月）,1例27个月内死亡。结论上皮样梭形细胞和细胞内黏液的出现是乳腺伴有神经内分泌分化癌的一个形态学特点。梭形细胞神经内分泌型导管内癌需要和普通导管增生及导管内乳头状瘤鉴别。梭形细胞型的神经内分泌癌和伴神经内分泌分化的梭形细胞浸润性癌需要与梭形细胞肌上皮肿瘤、恶性黑色素瘤及某些软组织肿瘤鉴别。     

中纵隔异位化生性胸腺瘤1例并文献复习

目的探讨罕见的起源于中纵隔异位化生性胸腺瘤(metaplastic thymoma, MT)的临床病理特点。方法回顾性分析1例中纵隔原发异位MT的临床病理学及免疫表型特征等并复习相关文献。结果患者男性,45岁,CT示左侧中纵隔肿块,临床无重症肌无力表现。镜下肿瘤表现为双相分化特征,岛状的上皮细胞区域与束状的梭形细胞区域交错分布并相互移行。上皮细胞为多角形,核空泡状,核仁小而明显,可见核沟和核内假包涵体。上皮细胞有轻度核异型,上皮岛内可见穿插有嗜酸性细支状透明物质。梭形细胞呈束状或席纹状结构排列。两种区域内均有大量泡沫细胞聚集和散在成熟小淋巴细胞、浆细胞浸润。肿瘤内缺乏未成熟T淋巴细胞。免疫表型:上皮细胞区域CKpan、p63强阳性,vimentin阴性。梭形细胞区域vimentin弥漫强阳性,非常少的梭形细胞CKpan弱阳性,p63阴性。间质淋巴细胞CD3、CD5阳性,TdT和CD1a阴性。EBV原位杂交检测结果为阴性。结论中纵隔异位MT是一类临床罕见的低度恶性肿瘤,明确诊断需依靠其独特的临床病理学特征。     

头皮低分化皮肤血管肉瘤的临床病理分析

目的 探讨头皮低分化皮肤血管肉瘤的临床免疫病理特征.方法 分析8例头皮低分化皮肤血管肉瘤患者的临床特点,观察其组织病理形态和CD31、CD34、第八因子相关抗原、波形蛋白、细胞角蛋白(AEl/AE3和CAM5.2)、上皮细胞膜抗原(EMA)、癌胚抗原(CEA)和S-100蛋白免疫组织化学染色.结果 患者平均发病年龄为69.0岁,男:女为5:3,临床早期常在头面部出现暗红斑,后期发生浸润性暗红斑块,均伴结节,偶发溃疡.组织病理检查示真皮广泛梭形细胞局部或广泛实性浸润,常见细胞异形,未见明确血管腔样结构.梭形细胞强阳性表达CD31、第八因子相关抗原和波形蛋白,弱阳性表达CD34、AEl/AE3和CAM5.2,而EMA、CEA和S-100蛋白阴性.结论 头面部出现淤斑样浸润性斑块和结节的老年患者,应及时做组织病理检查,CD31、CD34、第八因子相关抗原和波形蛋白免疫组织化学标记有助于明确诊断.     

甲状腺内化生型胸腺瘤1例并文献复习

目的探讨甲状腺内化生型胸腺瘤(metaplastic thymoma,MT)的临床病理学及免疫表型特征。方法复习1例MT的临床资料,进行组织病理学观察,采用免疫组化EliV ision两步法染色和EBER原位杂交检测,并结合文献进行讨论。结果患者女性,67岁,肿瘤直径4.6 cm,位于右侧甲状腺下极靠近胸骨上窝,境界清楚,包膜完整。镜下表现为双相性结构,由互相盘绕的上皮岛和短束状梭形细胞构成,两种成分在肿瘤的不同区域变化较大,部分区域由梭形细胞占优势的双相性结构构成,部分区域由纯梭形细胞构成。上皮细胞形成网格状或宽梁状吻合岛,形态类似非角化型鳞状细胞,胞核小而深染;部分上皮细胞较成熟,胞核大而空泡状,核内假包涵体易见,胞质嗜酸性。梭形细胞形态类似纤维母细胞,多排列成短束状、漩涡状、编织状或席纹状,可见胸腺小体样结构。背景有较多成熟小淋巴细胞浸润,梭形细胞区域散在较多微砂砾体。免疫表型:两种成分均弥漫表达EMA,BCL-2、CD99均弱阳性,Ki-67增殖指数约2%;上皮成分CKpan、CK5/6、p63均弥漫阳性,vimentin、CD5均阴性;梭形细胞vimentin弥漫阳性,CKpan、CK5/6、p63均阴性;间质小淋巴细胞CD3、CD5、CD20均阳性;TDT、CD1a、CD34、S-100、actin、Calretinin、D2-40等均阴性。原位杂交EBV呈阴性。结论 MT是一种极为罕见的交界性胸腺肿瘤,掌握其独特的组织学及免疫表型特征易于诊断和鉴别诊断,预后较好。     

非典型性纤维黄色瘤8例临床病理特征

目的 探讨非典型性纤维黄色瘤临床病理学特征、诊断及鉴别诊断。方法 收集8例非典型性纤维黄色瘤的临床资料，采用免疫组化EnVision两步法检测Connexin43、procollagen-1、CK(AE1/AE3)、EMA、CD68、CD99、vimentin、CD10、SMA、CD34、S-100、Ki-67的表达，并复习相关文献。结果 8例非典型性纤维黄色瘤患者，男女性各4例，年龄48～84岁，平均67.5岁；发生于面部4例，头颈部2例，右膝皮肤1例，右大腿皮肤1例；肿瘤最大径0.5～4.0 cm;临床均表现为皮肤表面隆起或溃疡。镜下肿瘤位于真皮内，由梭形细胞构成，细胞排列无序或呈条束状；可见散在分布的多形性细胞、多边形组织细胞样细胞、上皮样细胞、单核或多核瘤巨细胞，细胞异型明显，并可见病理性核分裂象。免疫表型：瘤细胞表达CD10(8/8)、CD68(8/8)、vimentin(8/8)、Connexin43(6/8)、procollagen-1(5/8)、CD99(1/8),不表达S-100、CD34、CK(AE1/AE3)、EMA、SMA,Ki-67增殖指数为5%～50%。结论...     

Type AB thymoma is not a mixed tumor of type A and type B thymomas,but a distinct type of thymoma

Type AB thymoma is generally regarded to be a mixture of type A and type B thymomas, but has not been studied extensively. In this study, we precisely investigated the characteristics of type AB thymoma immunohistochemically and compared it with other types of thymoma, including type A, metaplastic, and type B1 thymoma. In type A thymoma, the tumor cells were composed solely of pan-cytokeratin (CK-AE1/AE3)⁺ claudin-1⁺ vimentin^? epithelial membrane antigen (EMA)^? short spindle cells. Metaplastic thymoma exhibited biphasic architecture of epithelial islands of short spindle cells, which were phenotypically almost identical to the tumor cells in type A thymoma, and anastomosing bundles of CK-AE1/AE3^? claudin-1^? vimentin⁺ EMA⁺ fibroblast-like long spindle-shaped epithelial cells. Interestingly, we found that there were two distinctive subtypes of cell in type AB thymoma: the conventional subtype and the metaplastic subtype. The conventional subtype is characterized by type A-like components resembling type A thymoma. The metaplastic subtype is characterized by type A-like components extensively resembling the anastomosing bundles of fibroblast-like long spindle epithelial cells. Interestingly, the metaplastic subtype was a major subtype (14/19 cases), while the conventional subtype was a minor one (5/19 cases). In contrast to the rarity of metaplastic thymoma, the metaplastic subtype of type AB thymoma appears to be a major subtype of type AB thymoma.     

Ectopic hamartomatous thymoma in an immunocompromised male

Ectopic hamartomatous thymoma (EHT) is a rare benign neoplasm classically occurring in the lower neck of adult males. Here we present a case of EHT occurring in a 43-year-old immunocompromised male and a brief review of existing literature. The patient presented with a palpable mass overlying the left clavicle which, on imaging, showed a solitary nodule possibly eroding the cortical bone. A biopsy predominantly showed spindle cells that were immunopositive for keratin AE1/AE3 as well as weakly positive for CD99, SMA, and CD34. A diagnosis of synovial sarcoma was favored; at which point surgical resection was performed. The resected mass was well-demarcated with a tan-yellow cut surface. Microscopically, the lesion was composed of a mixture of spindle cells, glands, and mature adipose tissue. The spindle cells were plump with bland nuclei, and the epithelial component showed morphology similar to glands of salivary or breast tissue with a bilayered appearance (luminal and basal). No pleomorphism, mitotic figures, or necrosis was present. Immunohistochemical stains were performed and showed the spindle cells to express a myoepithelial phenotype (cytokeratin AE1/AE3, p63, calponin positive). The glands showed SMA and p63 positivity in the basal cells (similar to salivary gland and breast). Overall, given the clinical context, histomorphologic, and immunohistochemical profile, a diagnosis of EHT was made. At 12 months of follow-up there was no evidence of recurrence.     

小肠系膜淋巴结外滤泡树突状细胞肉瘤

目的 探讨淋巴结外滤泡树突状细胞肉瘤的临床病理学特征和免疫学表型。方法 对1例发生于小肠系膜的淋巴结外滤泡树突状细胞肉瘤进行光镜观察和免疫组化标记。结果 镜下显示特征性的双相性细胞结构，由旋涡状排列的胖梭形、卵圆形或多边性瘤细胞和大量混杂的小淋巴细胞组成。瘤细胞胞界不清，呈合体状。胞质淡嗜伊红色，核圆形或卯圆形，有清晰的核膜，染色质呈空泡状或点彩状，可见小核仁，灶性区域可见分叶状或多核性瘤细胞。瘤细胞核显示轻到中度的异型性，可见核分裂象。肿瘤内可见凝固性坏死灶。除与瘤细胞相混杂外，部分区域内可见淋巴细胞聚集于血管周围，形成袖套结构。免疫表型：瘤细胞表达CD21，弱阳性表达EMA，而CD35、S100蛋白、desmin和AE1／AE3等标记均为阴性，大多数小淋巴细胞表达CD45RO(UCHL-1)和CD3。结论 淋巴结外滤泡树突状细胞肉瘤是一种罕见的免疫辅助细胞中度恶性肿瘤，应予以完整切除，必要时辅以化疗和(或)放疗。     

Thymoma and thymic carcinoma arising in a thymolipoma: report of a unique case

Thymic carcinoma arising within a thymolipoma has not been reported previously. The authors present a unique case of thymoma and undifferentiated thymic carcinoma arising within a thymolipoma in a 36-year-old woman. The bulk of the resected mass was composed of benign fatty tissue admixed with foci of unremarkable thymic tissue; however, it also harbored a central solid mass showing undifferentiated thymic carcinoma associated with a type B2 thymoma. The carcinoma cells were positive for cytokeratin AE1/AE3, cytokeratin 19, and cytokeratin 8/18. They were negative for vimentin, cytokeratin 7, cytokeratin 20, CD5, epithelial membrane antigen, CD30, placental alkaline phosphatase, carcinoembryonic antigen, CD99, leukocyte common antigen, Epstein-Barr virus, inhibin alpha, and protein gene product 9.5. Rare tumor cells showed positive staining for chromogranin and synaptophysin.     

Wide spectrum screening keratin as a marker of metaplastic spindle cell carcinoma of the breast: an immunohistochemical study of 24 patients

Wide spectrum screening keratin as a marker of metaplastic spindle cell carcinoma of the breast: an immunohistochemical study of 24 patients
Aims : Metaplastic spindle cell carcinomas may be difficult to distinguish histologically from other spindle cell lesions in the breast. Variable staining with cytokeratin immunomarkers has been reported for metaplastic carcinomas. We evaluated the diagnostic utility of anti-cytokeratin polyclonal antibody, wide spectrum screening keratin, to assess spindle cell breast lesions.
Methods and results : Twenty-four patients with spindle cell breast carcinoma and 31 patients with benign or malignant spindle cell tumours were studied using a panel of antibodies directed against multiple cytokeratins (AE1/AE3, CAM5.2, wide spectrum screening keratin), epithelial membrane antigen (EMA), and vimentin. Sites of origin for the 31 controls included breast, bone, and soft tissue. All but one (95.8%) metaplastic carcinomas stained positively with wide spectrum screening keratin. Only rare or focal immunoreactivity was observed with AE1/AE3 in four cases; however, sensitivity of AE1/AE3 was improved in 13 cases using steam EDTA as an antigen retrieval technique. Three cases were immunoreactive with CAM5.2 and eight cases were immunoreactive with EMA. All control cases lacked immunoreactivity with the cytokeratin panel and EMA. The spindle cells in the metaplastic breast tumours (88%) and in the controls (97%) stained with vimentin.
Conclusions : Wide spectrum screening keratin may be the most useful and convenient antibody in differentiating metaplastic spindle cell carcinoma from other spindle cell lesions in the breast.     

Langerhans cells proliferation in ectopic micronodular thymoma with lymphoid stroma: a case report

Ectopic micronodular thymoma (MNT) is a rare tumor. We described a 76-year-old woman, who was referred to our institutional for a mass in the left cervical region. The Magnetic Resonance Imaging (MRI) scan showed a 3.7 cm × 1.7 cm × 2.0 cm mass. The neoplasm was composed of epithelial tumor cells arranged in a micronodular growth pattern set in a stroma showing lymphoid hyperplasia with germinal centers. Immunohistochemical studies showed that the neoplastic epithelial cells were reactive for AE1/AE3, CK5/6, P63, and the lymphoid component to be of mixed B- and immature T-cell lineage. Langerhans cells were confirmed within epithelial nodules for the first time with langerin, S-100, CD1a expression. We report a case of cervical ectopic MNT to emphasize the langerhans cells proliferation and the histopathologic features and differential diagnosis of the rare lesion to promote a better and broader understanding of this less understood subject.     

Ectopic hamartomatous thymoma: a case report with immunohistochemical and ultrastructural studies

A case of ectopic hamartomatous thymoma (EHT) arising in the supraclavicular region of a 52-year-old male is presented. The well-defined tumor measuring 1.7x1.5x0.7 cm consisted of three components: spindle cell (70%), epithelial (25%), and adipose (5%). The spindle cell component was characterized by sheet-like, haphazard and short fascicular arrangements of bland spindle cells. Neither mitotic figures nor cellular pleomorphism were found. Admixed with, and adjacent to, the spindle cell areas was an obviously epithelial component of variable appearance, ranging from glandular spaces lined by mainly cuboidal clear cells, irregularly anastomosing cords, and strands of epithelial cells to irregular solid nests of squamous epithelium with dark and clear cytoplasm. Myoepithelial cells were also observed. Immunohistochemically, the spindle cells were strongly and diffusely positive for cytokeratins and some of them were positive for BRST2, alpha-smooth muscle actin, and CD10. The tumor was negative for S-100 protein, glial fibrillary acidic protein, and CD34. Ultrastructurally, tonofilaments and desmosomes were observed in the spindle cells. The findings indicate an epithelial origin. The patient was well without recurrence or metastasis 8 months after excision. Pathologists and clinicians should be aware of the existence of ectopic hamartomatous thymoma in the supraclavicular or suprasternal region and should differentiate it from a high-grade sarcoma, such as biphasic synovial sarcoma or glandular malignant peripheral nerve sheath tumor.     

Acquired cystic disease-associated renal tumors: an immunohistochemical and fluorescence in situ hybridization study.

End-stage renal disease is associated with an increased incidence of renal cell neoplasms. Among these, recent studies have identified tumors with unusual histological patterns that do not fit into the categories recognized in the current classification system. These tumors often occur in kidneys with acquired cystic disease and are composed mainly of large eosinophilic cells arranged in solid, cribriform, acinar, or papillary patterns. They also contain deposits of calcium oxalate crystals. We investigated three eosinophilic epithelial tumors arising in kidneys with acquired cystic disease from three patients. Each of the tumors was composed of large eosinophilic cells arranged in solid, acinar, or tubulocystic architecture. Deposits of calcium oxalate crystals were present in each tumor. Hale's colloidal stain showed a positive cytoplasmic reaction in one of the neoplasms. Immunohistochemistry displayed positive results for CD10 (3/3), AE1/AE3 (3/3), alpha-methylacyl-CoA racemase (2/3), CAM5.2 (2/3), and vimentin (1/3). Reactions for epithelial membrane antigen, cytokeratin 7, and high molecular weight cytokeratin (34betaE12) were negative. Fluorescence in situ hybridization analysis showed no losses or gains of chromosomes 1, 2, 6, 10, or 17 in one tumor. There were gains of chromosomes 1, 2, and 6 in two tumors. One of these tumors also showed gains of chromosome 10. Eosinophilic renal cell tumors associated with acquired cystic disease have immunophenotypes and genetic profiles distinct from the renal cell neoplasms recognized in the current classification of renal cell neoplasia, and should be considered as a distinct clinicopathologic entity in the spectrum of renal cell neoplasia.