Positive Staining For Cytokeratin Research Articles

Ductal Adenocarcinoma of the Pancreas with Huge Cystic Degeneration: A Lesion to Be Distinguished from Pseudocyst and Mucinous Cystadenocarcinoma

Cystic neoplasms of the pancreas are rare and often mistaken for pseudocyst by imaging studies and macroscopic examination. We describe an unusual tumor of the pancreas composed of a mural nodule of anaplastic carcinoma arising from a huge ductal adenocarcinoma undergoing cystic degeneration. The cyst measured 27 x 13 x 4 cm. Light microscopy showed that the cyst was partly lined by a single layer of cuboidal to columnar tumor cells with focal mucin production and was surrounded by hyalinized connective tissue. Most lining epithelial cells were absent owing to extensive degenerative process. Immunohistochemical studies showed positive staining of cytokeratin and vimentin for pleomorphic giant tumor cells, which were negative for leukocyte common antigen (CD45), KP-1 (CD68), epithelial membrane antigen (EMA), and carcinoembryonic antigen (CEA). The ductal adenocarcinoma stained strongly positive for cytokeratin and EMA, and negative for vimentin, CD45, CD68, and CEA. The clinical course of the current case was extremely poor and the prognosis resembled that of an anaplastic carcinoma. Therefore, we like to emphasize the importance of complete excision and extensive sampling of any cystic neoplasms in the pancreas including those with large cystic component to avoid missing the malignant elements.

A role for extrarenal cells in the regeneration following acute renal failure

Recovery of renal function following acute tubular necrosis (ATN) is dependent on the replacement of necrotic tubular cells with functional tubular epithelium. The source of these new tubular cells is thought to be resident renal tubular cells. The discovery of pluripotent bone marrow-derived stem cells has led to a reexamination of the cellular source and processes involved in the recovery from organ injury. To test the hypothesis in humans that extrarenal cells participate in the recovery following ATN, we examined the origin of tubular cells in male patients with resolving ATN who had received a kidney transplant from a female donor. Immunohistochmistry of kidney biopsies was performed to identify renal tubular epithelial cells (cytokeratin positive) and leukocytes (CD45 positive). Fluorescent in-situ hybridization was used to detect Y chromosome containing cells with DAPI serving as a nuclear stain. All staining was performed on the same section. The Y chromosome was detected in approximately 40% of tubular cell nuclei in male kidneys (positive control) and in no nuclei of female kidneys (negative control). In male recipients of female kidneys who developed ATN, 1% of tubules contained Y chromosome cells defined by their morphology, positive staining for cytokeratin, and negative staining for CD45. When present, multiple cells in a positive tubule stained for the Y chromosome. No Y chromosome containing tubular cells were seen in similar sex mismatched transplants in male recipients who did not develop ATN, suggesting that recipient derived cells do not routinely repopulate the transplanted kidney. This proof-of-principle clinical observation demonstrates that extrarenal cells can participate in the regenerative response following ATN. These findings provide rationale for the cellular therapy of acute renal failure.

Immortalization of human urethral epithelial cells: a model for the study of the pathogenesis of and the inflammatory cytokine response to Neisseria gonorrhoeae infection.

The primary human urethral epithelial cells developed by our laboratory have been immortalized by transduction with a retroviral vector expressing the human papillomavirus E6E7 oncogenes. Analysis of telomerase expression and comparison to that in primary cells revealed detectable levels in the transduced human urethral epithelial cells. Immortalized urethral cells could be passaged over 20 times. Immunofluorescence microscopy studies showed that the immortalized cells were phenotypically similar and responded to gonococcal infection similarly to primary cells. Specifically, positive cytokeratin staining showed that the immortalized cells are keratinocytes; cell surface levels of human asialoglycoprotein receptor increase following gonococcal infection, and, like the primary cells, the immortalized urethral epithelial cells are CD14 negative. Using enzyme-linked immunosorbent assay, we found that interleukin-6 (IL-6) and IL-8 levels in primary urethral epithelial cell supernatants increase after challenge with N. gonorrhoeae. Likewise, the immortalized urethral epithelial cells produced higher levels of IL-6 and IL-8 cytokines in response to gonococcal infection. Cells challenged with a gonococcal lipid A msbB mutant produced reduced IL-6 and IL-8 levels when compared to the parent strain. Additionally, these data suggest that the 1291 msbB lipooligosaccharide may suppress cytokine induction.

Ameloblastic fibroma: Report of a case

A 3-year-old girl was referred to our hospital on January 22, 1999 after a swelling developed in the right cheek a few days after trauma to that area. Her medical, surgical, family, and social histories were unremarkable. A systemic review was within normal limits, and no medication had been administered. Intraoral examination showed a hard swelling in the right mandibular body. A panoramic radiograph showed a large, multilocular, radiolucent lesion with scalloped margins. It extended from the right first deciduous molar area to the ascending ramus and coronoid process (Fig 1). The radiograph also revealed expansion of the cortex and resorption of the roots of the lower right second deciduous molar. A displaced, developing permanent first molar was associated with the lesion. The clinical diagnosis was dentigerous cyst. Enucleation of the lesion, extraction of the lower right permanent first molar crown, and open packing were performed under general anesthesia. During the surgery, the lesion was found to be encased in bone. It measured 4 3 16 cm, was dark brown, and was soft in consistency. It was removed in pieces and the surrounding bone was curetted. The inferior alveolar nerve was preserved during the procedure and the patient retained normal sensation. Furacin gauze was used as the packing material. Packing was continued for 30 days and the gauze was changed daily. Microscopic examination of the tissue showed the presence of dental lamina-like strands, cords, and nests of odontogenic epithelium within a dental papilla-like myxomatous mesenchymal matrix (Fig 2). Positive cytokeratin staining was seen in the odontogenic epithelium, while positive vimentin staining was observed in some areas of the immature, dental papilla-like cells and in the basement membrane of the odontogenic epithelium (Figs 3, 4). No tumor was found in the tissue curetted from the surrounding bone. The final diagnosis was ameloblastic fibroma. Different areas of the specimen showed different histologic findings (Figs 5, 6). No calcified dental structures were apparent in the specimen. Areas of mesenchymal tissue without epithelial strands were present, and large areas devoid of ameloblastic strands and dental papilla were also seen (Fig 5). Mesenchymal growth appeared to be more active in areas devoid of epithelium (Fig 6). The postoperative course was uneventful and the patient was discharged for further follow-up. Healing was uneventful and there were no signs of recurrence 22 months after surgery (Fig 7).

Ductal Cell Carcinoma of the Kidney with Extensive Signet Ring Cell Mucosecreting AreasA Case Report with Immunohistochemical Analysis

We present the case of a 45-year-old patient with a renal ductal cell carcinoma arising in the Bellini ducts that was composed of histologically well-differentiated tubulopapillary and cystic areas with desmoplastic stroma, extensive mucosecreting areas, and regions depicting a transition between these two constituents. The mucosecreting component was mostly formed by signet ring tumor cells containing cytoplasmic Alcian blue-PAS-stainable mucins. The tubulopapillary and cystic areas of the tumor showed the immunohistochemical staining for low and high molecular weight cytokeratin, EMA, vimentin and Ulex europaeus, characteristic of ductal cell carcinoma. The mucosecreting cells also presented intense positive staining for cytokeratin and vimentin, and this is quite similar to observations reported in some forms of gastrointestinal cancer with rhabdoid features that are indicative of poor prognosis. Our findings suggest that mucosecreting areas with signet ring cells represent an extreme metaplastic change that can seldom occur in certain forms of renal tumors.

Anatomical studies of the urethral plate: why preservation of the urethral plate is important in hypospadias repair.

To describe the detailed anatomy of the urethral plate in relation to its controversial role in hypospadias surgery. A newborn penis with proximal penile hypospadias and two fetal penises with distal shaft hypospadias were included in the study; 30 normal fetal penises served as the control. Specimens were embedded in paraffin and serially sectioned (6 microm) after formalin fixation. Every 10th section was stained with haematoxylin and eosin. Immunohistochemical staining for nerves (S100), smooth muscles (alpha-actin), blood vessels (factor VIII) and epithelium (cytokeratins 7, 14 and 18) were used on selected sections, with particular attention to the urethral plate. Masson's trichrome and Sirius Red stains were used to localize collagen. There were extensive blood vessels, glands and smooth muscle under the urethral plate in the hypospadias specimens. These relatively well organized tissues corresponded to an abnormally formed corpus spongiosum. The glands underneath the urethral plate and adjacent to the normal urethra showed positive staining for cytokeratins 7 and 18, respectively (markers of endodermal origin) but were negative for cytokeratin 14 (a marker of ectodermal origin). Penile skin and urethral plate epithelium stained positively for cytokeratin 14 but not for cytokeratin 7 and 18. The urethral plate has a rich nerve supply, as determined by S100 staining. Collagen intensity under the urethral plate was no different from that in normal areas. Tunica albuginea stained intensely for type I and III collagen. These results show that the urethral plate is well vascularized, has a rich nerve supply and an extensive muscular and connective tissue backing. These features may explain the lower complication rate with onlay flaps than with tube flaps. Therefore, from these anatomical findings, we continue to advocate preservation of the urethral plate and the onlay island flap for hypospadias reconstruction.

Colonic adenocarcinoma metastatic to the thyroid gland: a case report with immunohistochemical investigation

Clinically evident metastases of carcinomas to the thyroid gland are rare, particularly from a colorectal primary tumor. We present a case of colonic adenocarcinoma metastatic to the thyroid gland with histopathologic and immunohistochemical findings. A 68-year-old woman with a history of Dukes' stage B colon carcinoma presented a mass in the thyroid gland. The tumor was confirmed to be metastatic adenocarcinoma from the colon. The immunohistochemical findings demonstrated positive staining for cytokeratin 20, low-molecular-weight cytokeratin, villin and carcinoembryonic antigen, but stains were negative for cytokeratin 7 and thyroglobulin.

Spontaneous choroid plexus carcinoma in an albino rat

Neoplasms of the choroid plexus are very rare in the rat, and few cases have been described. We report on a spontaneously occurring choroid plexus carcinoma arising from the fourth ventricle in a 2-year-old female albino rat. The infiltrative growth was observed in the adjacent brain parenchyma, in the wall of the vessels of the circle of Willis, in the perivascular space of VIRCHOW and ROBIN and in the leptomeninges. Immunohistochemical investigations demonstrated positive staining for cytokeratin (Lu-5) indicating that choroid plexus tumors in the rat express epithelial differentiation. The diagnosis was made on the basis of microscopical and immunohistochemical findings.

Fluorescent activated cell sorting to isolate canine microvascular endothelial cells from adipose tissue

Adipose tissue offers an abundant source for isolation of microvascular endothelial cells (MVECs). Several cell types result from the enzymatic digestion of adipose tissue, including MVECs, mesothelial cells and fibroblasts. Pure populations of MVECs must be isolated from the mixed cultures or fibroblasts overgrow the population. Canine subcutaneous or mesenteric fat is obtained during elective surgical procedures and digested with collagenase. Microvascular endothelial cells are separated from capillary fragments by Percoll gradient centrifugation and plated in culture. At confluence, microscopic identification of most cultured cells indicate the typical cobblestone morphology of ECs, while other spindle shaped cells resemble fibroblasts. Micro- vascular endothelial cells are identified by their uptake of acetylated-low density lipoprotein (Ac-LDL). Mesothelial cells, which closely resemble MVECs in morphology, and fibroblasts are removed from cultures of MVECs using a fluorescent activated cell sorter (FACS). Acetylated-low density lipoprotein tagged with a fluorescent probe, 1,1′-dioctadecyl-3,3,3′,3′-tetramethyl- indocarbocyanine perchlorate (DiI), is incubated with the mixed cultures and the cells are sorted using a FACS. The pure populations of MVECs that result are tested immunocytochemically and are identified by their positive staining with antibodies against factor VIII related antigen. Mesothelial cells are identified by positive staining for cytokeratin 18 antibody. Contaminating fibroblasts show negative staining for smooth muscle alpha actin, cytokeratin 18 and factor VIII related antigen antibodies. This study examines the efficiency of the fluorescent activated cell sorter to obtain pure populations of MVECs harvested from adipose tissue.

A simple method for the isolation and culture of epithelial and stromal cells from benign and neoplastic prostates

Objectives. Current primary prostate cell culture techniques use an overnight digestion or extensive media preparation. In this report, we describe a method for the culture of benign and neoplastic cells from human prostatectomy specimens that is rapid and contains no undefined factors in the medium. Methods. Characterization of the human cultured prostate cells was performed using immunohistochemical methods and monoclonal antibodies AE1/AE3 and cytokeratin 8, as well as monoclonal antibodies against prostate-specific antigen (PSA). Polymerase chain reaction was used to measure the exclusive epithelial and stromal cell products, c-met and hepatocyte growth factor (HGF), respectively. Electron microscopy was performed to assess the cell junctions and morphologic features of epithelial cells. Optimum cell growth in different media was tested using a cell replication assay. Results. Microscopic evidence revealed that the cells demonstrate typical epithelial morphology, with polyhedral cells forming tight junctions in a continuous monolayer. Desmosomes were present in electron micrographs of epithelial cells. The cultured epithelial cells described in this report also demonstrate positive cytokeratin staining. The epithelial cells reacted positively with PSA antibody, indicating that the cells retain their secretory role in cell culture for a limited period. Epithelial cells expressed the HGF receptor, c-met; stromal cells secreted HGF. Insulin, transferrin, and selenium increased the growth of cells in the chemically defined media, compared with minimum essential media (MEM) and Ham's F12. Conclusions. In summary, essentially pure cultures of prostate stromal or epithelial cells have been established using simple isolation and culture methods. These cells will be useful for the investigation of related growth factors, such as insulin-like growth factor I and insulin-like growth factor II, and in understanding the basis for stromal-epithelial cell interactions.

Isolation and primary culture of murine alveolar type II cells.

Previous attempts to culture mouse alveolar type II (ATII) cells have been hampered by limited purity and cell recovery. We have now obtained culturable ATII cells from female C57BL/6 mice at a purity of 92% +/- 3 (mean +/- SD; n = 20), with viabilities of 96% +/- 2 and total yields of 5.1 +/- 0.7 X 10(6) cells per mouse. Crude lung cell suspensions were prepared by intratracheal instillation of Dispase and agarose followed by mechanical disaggregation of the lungs. Crude cell suspensions were purified by negative selection using a biotinylated-antibody, streptavidin-coated biomagnetic particle system. Cell purities were determined by Pap staining and confirmed ultrastructurally. Purified ATII cells were cultured on fibronectin-coated chamber slides and maintained for up to 5 days in DMEM with 10% fetal bovine serum. Cultures exhibited minimal contamination by Clara cells, mesenchymal cells, or endothelial cells, and the epithelial nature of the cultures was confirmed by positive cytokeratin staining in at least 97% of the cells through day 5. Day 3 cultures demonstrated osmium tetroxide/tannic acid-stained granules consistent with lamellar bodies in 76% +/- 3.6 of the cells. The cultures displayed features distinct from those previously described for adult rat ATII cells, including irregularly-shaped cells and the formation of numerous cytoplasmic projections in direct contact with other cells. These studies indicate that excellent yields of highly purified, culturable ATII cells can be obtained from genetically defined mice. These techniques may provide powerful new models for the study of parenchymal lung disease in vitro.

Alopecia areata in a patient with pili annulati

tend to aggregate at the periphery of the tumor masses, resulting in an inflammatory “cuff.” Each tumor has a variable content of collagenized, fibroblastic stroma that serves to compartmentalize individual aggregates of tumor cells in some areas. Our case showed these histologic features with significant pilosebaceous differentiation and a prominent vascular component (Fig. 1). All cases of LELCS have shown positive staining for cytokeratins, favoring an epidermal, follicular, or sudoriferous origin. More than half were positive for EMA, favoring a sudoriferous origin for this neoplasm. However, squamous cell carcinomas and sebaceous carcinomas can show also EMA-positive 2. Carbone A, Micheau C. Pitfalls in microscopic diagnosis of undifferentiated carcinoma of the nasopharyngeal type (lymphoepithelioma). Cancer 1982$0:1344-50. 3. Klijanienko J, Micheau C, Azli N, et al. Undifferentiated carcinoma of the nasopharyngeal type of the tonsil. Arch Otolaryngol Head Neck Surg 1989;115:731-3. 4. Bosch JD, Kudryk WH, Johnson GH. The malignant lymphoepithelial lesion of the salivary glands. J Otolaryngol 1988;17:187-90. 5. Butler AE, Colby TV, Weiss L, et al. Lymphoepithe lioma-like carcinoma of the lung. Am J Surg Path01 1989; 13632-5. 6. Begin LR, Eskandari J, Joncas J, et al. Epstein-Barr virus related lymphoepithelioma-like carcinoma of the lung. J Surg Oncol 1987;36:280-5. 7. Wick MR, Scheithauer BW, Weiland LH, et al. Primary thymic carcinomas. Am J Surg Path01 198%6:61320.

Presence of the intermediate filaments cytokeratins and vimentin in the rat corpus luteum during luteal life-span.

The presence of the intermediate filament (IF) proteins cytokeratins and vimentin in corpus luteum (CL) and other parts of the ovary from adult pseudopregnant rats was investigated using immunohistochemistry and immunoblot analysis. To induce pseudopregnancy, female rats were mated with sterile male rats. The mating procedure induces a prolonged luteal life-span of 13 +/- 1 days. Positive staining for cytokeratin could be seen in CL, in the theca layer of follicles, and the ovarian surface epithelium with the broad-spectrum monoclonal antibody cocktail AE1/AE3. Weak staining was also seen in CL with antibodies against cytokeratins 8 and 18. A similar distribution was also seen for vimentin, which furthermore was detected in blood vessels. No changes in staining intensity was seen in CL of different luteal age. The strong staining for vimentin in CL was confirmed by immunoblot analysis, where one main band of 57 kDa was observed from day 1 to day 19 of pseudopregnancy. Expression of the IF proteins investigated seems to start in the newly formed CL and the continuous expression indicates that they are not directly regulated by luteal steroids.

Identification of occult micrometastases in pericolic lymph nodes of Duke's B colorectal cancer patients using monoclonal antibodies against cytokeratin and CC49. Correlation with long-term survival.

Patients with transmurally invasive, lymph node negative colorectal carcinoma (Dukes' B) have a 5-year survival rate ranging from 53.9% to 84.9%. The authors postulate that patients with Dukes' B colon cancer who die of their disease have occult micrometastases in their pericolic lymph nodes at the time of original diagnosis. In an attempt to identify these occult micrometastases, pericolic lymph nodes from Dukes' B colon cancer resections were stained retrospectively with antibodies against cytokeratin (anti-keratin AE1/AE3, Boehringer Mannheim, Indianapolis, IN) and CC49 (a second-generation monoclonal antibody directed against TAG-72. The authors reviewed all Dukes' B (transmurally invasive, lymph node negative) primary colorectal carcinoma resection specimens from the surgical pathology files of the Ohio State University Hospitals between 1984 and 1987. Survival data were obtained from the Tumor Registry of the Arthur G. James Cancer Hospital and Research Institute, Columbus, Ohio. The results were analyzed by univariate and multivariate analysis. Fifty cases with 568 lymph nodes (11.3 per case) were examined with each antibody using standard immunoperoxidase techniques. Positive staining for cytokeratin was seen in 14 patients (33 lymph nodes), 6 of whom died of colon cancer within 66 months (43%). Only 1 of the 36 patients with cytokeratin-negative lymph nodes died of colon cancer over the same time period (3%, P = 0.0009 univariate, P = 0.0013 multivariate). There was no significant difference in survival between the CC49-positive and CC49-negative groups. Immunoperoxidase techniques are capable of identifying micrometastatic disease in lymph nodes missed by routine hematoxylin and eosin staining. Further, the presence of cytokeratin-positive cells within lymph nodes correlated with a significantly poorer prognosis. Therefore, cytokeratin staining of pericolic lymph nodes in patients with Dukes' B colorectal cancer is recommended. Larger multicenter studies are needed, however, to confirm these results and to evaluate the appropriateness of adjuvant chemotherapy in patients whose disease is upstaged by immunohistochemical staining.

Polyphenotypic Small-Cell Orbitocranial Tumor

A male infant was born with a massive orbitocranial tumor without evidence of metastasis. On light microscopy, the histologic pattern of the tumor was that of a largely necrotic and highly undifferentiated small round cell neoplasm of uncertain origin. Ultrastructural features of the primitive cells included a rare tight junction and myofibril. Immunohistochemical studies showed positive staining for cytokeratin, vimentin, muscle-specific actin, neuron-specific enolase, and S100 protein and negativity for desmin and leukocyte common antigen. We believe this case represents an example of a polyphenotypic small-cell tumor of childhood with epithelial, rhabdomyoblastic, and neuroectodermal differentiation.

Multicystic mesothelial proliferation. Immunohistochemical, ultrastructural and DNA analysis of five cases.

We investigated the clinicopathological findings in five cases of multicystic mesothelial proliferation (MMP). All masses consisted of multiloculated cysts attached to pelvic organs and sometimes growing into the upper abdominal cavity. The cystic spaces were lined by flattened or cuboidal cells. The stroma showed fibrosis, oedema and chronic inflammation. Immunohistochemistry revealed strong positive staining for cytokeratin and epithelial membrane antigen, and focal positivity for vimentin and carcinoembryonic antigen. The endothelial markers were negative. Electron microscopy showed abundant surface microvilli and well-developed basal lamina. DNA analysis identified euploid cell populations in all cases. All but one case had a previous history of abdominal surgery. Despite the worrying appearance the clinical outcome was favourable in all cases; there was one recurrence. Clinical and pathological data support the hypothesis that MMP represent a reactive mesothelial proliferation and not a neoplastic process.

Characterization of murine cell lines from diethylstilbestrol-induced uterine endometrial adenocarcinomas.

Neonatal treatment with estrogens is associated with development of uterine adenocarcinomas in CD-1 mice. Treatment with the synthetic estrogen diethylstilbestrol (DES) on Days 1 to 5 after birth results in 90% incidence of these hormone-dependent lesions in 18-mo.-old mice. Three cell lines were established from these DES-associated tumors. Each of these cell lines exhibited morphologic and ultrastructural characteristics of transformed epithelial cells, including an increased nuclear:cytoplasmic ratio, enlarged and irregular nuclei with multiple nucleoli and areas of chromatin condensation, positive staining for cytokeratin, desmosomes, and microvilli. After subcutaneous injection into nude mice, all three cell lines formed solid tumors within 4 wk. Although the primary uterine tumors and tumor transplants in nude mice had been shown to be estrogen-dependent and estrogen-receptor positive, neither the monolayer growth nor the tumorigenicity of any of the three cell lines in this study was enhanced by or dependent on estrogen. Estrogen receptor levels were low in early and intermediate passage cells. Allele-specific oligonucleotide hybridization analysis of PCR-amplified cell line DNA revealed no point mutations in the 12th, 13th, or 61st codons of the K-ras or H-ras protooncogenes. Southern analysis revealed no changes in genomic organization of the putative tumor suppressor gene DCC, but demonstrated a three- to four-fold amplification of the c-myc gene in one cell line. Expression of c-myc RNA was concomitantly increased in the same cell line. These three transformed cell lines represent the end point in the process of hormone-associated tumorigenesis and as such should prove useful in investigating the molecular changes and the mechanisms involved in hormonal carcinogenesis.

Detection of occult metastases in pancreatic adenocarcinoma with anticytokeratin antibody.

Fifty-six lymph nodes excised from 11 patients with pancreatic adenocarcinoma were studied for evidence of metastasis by standard light microscopy and immunohistochemistry using an anticytokeratin monoclonal antibody. Eight of 56 nodes contained metastatic carcinoma as demonstrated by conventional techniques. By immunohistochemistry, positive-staining cells were easily identified. In 10 of 56 nodes, the positive staining was accompanied by cytologic atypia, changes consistent with malignancy. In seven additional nodes, positive-staining cells were present, but cytologic atypia was lacking. The use of immunohistochemistry facilitated recognition of malignant cells and raised questions that single-cell metastasis may be present. Positive staining for cytokeratin should prompt a close examination of cells to determine if morphologic features of malignancy are present.

Comparative immunohistochemistry of malignant fibrous histiocytoma and sarcomatoid carcinoma of the urinary tract

An immunohistochemical analysis using antibodies to cytokeratin, epithelial membrane antigen, alpha-1-antitrypsin, alpha-1-antichymotrypsin and factor XIIIa was performed in four cases of malignant fibrous histiocytoma and five cases of sarcomatoid carcinoma in the urinary tract. All cases of malignant fibrous histiocytoma showed positive staining for factor XIIIa, alpha-1-antitrypsin and alpha-1-antichymotrypsin. No case was positive for factor XIIIa, but one case with sarcomatoid carcinoma stained positive for alpha-1-antitrypsin and alpha-1-antichymotrypsin. All cases showed positive staining for cytokeratin and 4 cases with sarcomatoid carcinoma were positive for epithelial membrane antigen, but no cases with malignant fibrous histiocytoma were positive. Immunohistochemical analysis would thus help to distinguish malignant fibrous histiocytoma from sarcomatoid carcinoma of the urinary tract.

In vitro tramsformation of rat bladder epithelium by 2-amino-4-(5-nitro-2-furyl)thiazole

To establish a rat urinary bladder carcinogenesis model in vitro, primary rat bladder epithelial cells were grown in media containing 2-amino-4-(5-nitro-2-furyl)thiazole (ANFT), the water-soluble metabolite of N-[4-(5-nitro-2-furyl)-2-thiazolyl]-formamide (FANFT), for 4 weeks followed by long-term (4-7 months) exposure to control medium, sodium saccharin (NaS), or urea. Another set of cultures were exposed to ANFT, NaS and urea simultaneously. Several phenotypic changes were observed in the chemically exposed cell cultures, namely differences in cell morphology, increased growth rate and the ability to grow on plastic instead of rat-tail collagen support. All of the chemically exposed cultures were anchorage independent except one of those treated with NaS. The ANFT-treated cells followed by control medium or urea and cells treated with ANFT, NaS and urea were tumorigenic when transplanted to nude mice, whereas NaS or ANFT followed by NaS treatment were not. The tumors were carcinomas and their epithelial differentiation was verified by strong positive staining for cytokeratin. These studies demonstrate the urothelial transforming capability of ANFT in cell culture without the necessity for a long exposure to a secondary chemical.