Antibodies to intermediate filament proteins in the diagnosis and classification of human tumors

A novel cuproptosis-related lncRNAs signature predicts prognostic and immune of bladder urothelial carcinoma

Bladder Urothelial Carcinoma (BLCA) remains the most common urinary system tumor, and its prognosis is poor. Cuproptosis is a recently discovered novel cell death involved in the development of tumor cells. However, the use of cuproptosis to predict the prognosis and immunity of Bladder Urothelial Carcinoma remains largely unclear, and this study was designed to verify cuproptosis-related long non-coding RNAs (lncRNAs) to estimate the prognosis and immunity of Bladder Urothelial Carcinoma. In our study, we first defined the expression of cuproptosis-related genes (CRGs) in BLCA, and 10 CRGs were up- or downregulated. We then constructed a co-expression network of cuproptosis-related mRNA and long non-coding RNAs using RNA sequence data from The Cancer Genome Atlas Bladder Urothelial Carcinoma (TCGA-BLCA), clinical features and mutation data from BLCA patients to obtain long non-coding RNAs by Pearson analysis. Afterward, univariate and multivariate COX analysis identified 21 long non-coding RNAs as independent prognostic factors and used these long non-coding RNAs to construct a prognostic model. Then, survival analysis, principal component analysis (PCA), immunoassay, and comparison of tumor mutation frequencies were performed to verify the accuracy of the constructed model, and GO and KEGG functional enrichment analysis was used to verify further whether cuproptosis-related long non-coding RNAs were associated with biological pathways. The results showed that the model constructed with cuproptosis-related long non-coding RNAs could effectively evaluate the prognosis of BLCA, and these long non-coding RNAs were involved in numerous biological pathways. Finally, we performed immune infiltration, immune checkpoint and drug sensitivity analyses on four genes (TTN, ARID1A, KDM6A, RB1) that were highly mutated in the high-risk group to evaluate the immune association of risk genes with BLCA. In conclusion, the cuproptosis-related lncRNA markers constructed in this study have evaluation value for prognosis and immunity in BLCA, which can provide a certain reference for the treatment and immunity of BLCA.

Quantitative evaluation of myenteric ganglion cells in normal human left colon: implications for histopathological analysis

The analysis of myenteric neurons is becoming increasingly important for the assessment of enteric nervous system injury and degeneration occurring in motor disorders of the gut. Limited information is presently available on the quantitative estimation of myenteric neurons and glial cells in paraffin-embedded colonic sections; additional data would be useful for diagnostic purposes. In this morphometric study, we performed immunohistochemistry to count myenteric neurons and glial cells in paraffin sections of human colon. Serial cross sections of formalin-fixed paraffin-embedded full-thickness normal human left colon (n = 10, age-range: 50-72 years) were examined. HuC/D and S100beta antigens were found to be the best markers for the detection of neurons and glial cells, respectively. Significant correlations were noted between the numbers of neurons/glial cells and the respective myenteric ganglion areas. These findings suggest that HuC/D-S100beta-immunostained paraffin cross sections of human colon can be regarded as valuable tools for the quantitative estimation of myenteric neurons and glial cells. Based on the present method, only a limited number of paraffin sections are needed for reliable quantitative assessments of myenteric ganglion cells, thus allowing fast and simple approaches in the settings of the histopathological diagnosis of colonic motility disorders and retrospective evaluations of pathological archival tissue specimens.

Involvement of cytoskelatal proteins and growth factor receptors during development of the human eye

The spatial and temporal distribution of nestin, cytokeratins (CKs), vimentin, glial fibrillary acidic protein (GFAP), neurofilaments (NFs), beta-tubulin as well as fibroblast growth factor receptors (FGFRs) and platelet-derived growth factor receptor beta (PDGF-Rbeta) were investigated in the developing human eye in eight conceptuses of 5-9 postovulatory weeks using immunostaining. Nestin was found in the neuroglial precursors and the radial glial fibres of the optic nerve. In the pigmented retina, nestin was present only in the 5th week, while at later stages (6-9th week), co-expression of CKs and vimentin was seen. Nestin, CKs, vimentin, and GFAP were observed in the precursors to various cell types in the neural retina. Additionally, their expression was also apparent in the lens epithelium, showing its gradual fading following the lens fibre elongation. They appeared in the mesenchymal cells of the cornea, the choroid, the sclera, and the corpus vitreum, too. In the corneal epithelium, co-expression of nestin and CKs was detected. NFs and beta-tubulin were confined to the differentiating retinal neuroblasts. Growth factor receptors were seen in the retina, the lens epithelium while less intensely in the lens fibres, the corneal epithelium, and the mesenchymal cells. During the early eye development (5-9th week), IFs expressing normal pattern of distribution as well as acting in concert might contribute to the normal developmental processes occurring in certain parts of the human eye. Additionally, NFs and beta-tubulin seem to have an important role in the retinal ganglion cell differentiation, while FGFRs and PDGF-Rbeta may regulate the cell proliferation, differentiation, and survival in various parts of the developing eye.

Epithelioid hemangioendothelioma of the nasal cavity

Epithelioid hemangioendothelioma (EH) is an unusual vascular neoplasm characterized by proliferation of endothelial cells with epithelioid morphology. It has an indolent course, with the potential for recurrence, but rarely metastasizes. The common locations include soft tissue, skin, viscera and bone. We present an unusual case of EH in the nasal cavity and describe the clinical characteristics, histopathologic findings, differential diagnosis and management. The 25-year-old male patient initially presented with an 8-month history of intermittent epistaxis. Nasal endoscopy revealed a vascular tumor involving the nasal cavity. The tumor was excised and the final histopathologic diagnosis was consistent with EH. EH in the head and neck is extremely rare. Wide excision is the treatment of choice, and regular follow-up is suggested due to the potential for recurrence. Definitive diagnosis depends on histopathologic and immunohistochemical features.

Anaplastic carcinoma of the thyroid with rhabdomyosarcomatous differentiation: a report of two cases

Anaplastic carcinoma of the thyroid gland (ACT) is a highly malignant tumor that is almost invariably associated with a fatal outcome. It demonstrates a variety of peculiar histological features, with squamoid, giant cell and spindle cell growth patterns. The spindle cell variant of ACT is usually indistinguishable from a true sarcoma and it can simulate fibrosarcoma, malignant fibrous histiocytoma (MFH), hemangiopericytoma and angiosarcoma or rhabdomyosarcoma. Although a rhabdomyosarcomatous appearance has sometimes been mentioned in the literature, true skeletal muscle differentiation has never been consistently proved. We report two cases of ACT with rhabdomyosarcomatous differentiation, as demonstrated by means of immunohistochemistry and electron microscopy. Both cases disclosed a very similar histological appearance, with a main population of small, pleomorphic, round-to-oval cells arranged in a storiform pattern, admixed with scattered pleomorphic giant cells, an image similar to that of the usual type of MFH. Stains for epithelial markers showed only few, scattered, weakly positive cells. Thyroglobulin and calcitonin were negative in tumor cells in both cases. On the contrary, positivity to vimentin was strong and generalized. Immunomarkers of muscular differentiation showed a consistent positivity. At the ultrastructural level, the cells disclosed the same spindle and pleomorphic morphology, with large, bizarre nuclei and cytoplasm with abundant mitochondria, rough endoplasmic reticulum, secretory granules and lipid droplets. There were also cells with wide cytoplasm filled with filamentous material, either of actin or myosin, as well as Z-band material. In conclusion, the cases reported here show a clear-cut rhabdomyosarcomatous differentiation of ACT, confirmed both immunohistochemically and ultrastructurally, a feature not previously reported in the literature. These findings may contribute to the broadening of the differentiation spectrum of this unusual neoplasm.

Phenotyping of protein-prion (PrPsc)-accumulating cells in lymphoid and neural tissues of naturally scrapie-affected sheep by double-labeling immunohistochemistry

Transmissible spongiform encephalopathies are fatal neurodegenerative diseases characterized by amyloid deposition of protein-prion (PrPsc), the pathogenic isoform of the host cellular protein PrPc, in the immune and central nervous systems. In the absence of definitive data on the nature of the infectious agent, PrPsc immunohistochemistry (IHC) constitutes one of the main methodologies for pathogenesis studies of these diseases. In situ PrPsc immunolabeling requires formalin fixation and paraffin embedding of tissues, followed by post-embedding antigen retrieval steps such as formic acid and hydrated autoclaving treatments. These procedures result in poor cellular antigen preservation, precluding the phenotyping of cells involved in scrapie pathogenesis. Until now, PrPsc-positive cell phenotyping relied mainly on morphological criteria. To identify these cells under the PrPsc IHC conditions, a new, rapid, and highly sensitive PrPsc double-labeling technique was developed, using a panel of screened antibodies that allow specific labeling of most of the cell subsets and structures using paraffin-embedded lymphoid and neural tissues from sheep, leading to an accurate identification of ovine PrPsc-accumulating cells. This technique constitutes a useful tool for IHC investigation of scrapie pathogenesis and may be applicable to the study of other ovine infectious diseases.

Patterns of nestin and other intermediate filament expression distinguish between gastrointestinal stromal tumors, leiomyomas and schwannomas

The KIT-positive specific gastrointestinal stromal tumors (GISTs), leiomyomas, and schwannomas are the three most common types of primary mesenchymal tumors of the gastrointestinal (GI) tract. The intermediate filaments are abundant cytoskeletal proteins commonly used as cell differentiation markers in diagnostic immunohistochemistry. Their patterns have not been fully characterized in GI mesenchymal tumors, and could offer differential diagnostically useful parameters. Very recently, nestin, a class VI intermediate filament expressed in neuroectodermal stem cells and skeletal muscle progenitor cells, has been shown in GISTs and suggested as a marker for these tumors. In this study we immunohistochemically examined the expression of nestin and other intermediate filament proteins, including desmin, keratins (Ks), glial fibrillary acidic protein (GFAP), neurofilament, and vimentin in GISTs of different sites, esophageal leiomyomas and GI schwannomas. Nestin was nearly consistently present in GISTs of different locations whether spindle cell or epithelioid, and benign or malignant. It was also detected in 23 of 24 (96%) GI schwannomas, whereas leiomyomas were uniformly negative. Vimentin was present in both GISTs and schwannomas, whereas it was typically absent in leiomyomas (25% positive, usually focally). Desmin was present in all leiomyomas, whereas only 3% of GISTs (4 of 140) were positive, and all schwannomas were negative. K18 was detected in a minority of GISTs, leiomyomas, and schwannomas. Malignant GISTs were more commonly keratin positive than the benign ones; there was 18% K18 positivity in malignant gastric and small intestinal GISTs, but 9% K18 positivity in benign gastric and small intestinal GISTs. Moreover, K8, albeit to a lesser degree, was detected in a minority of GISTs, but K7, K14, K19 and K20 were not detected. GFAP was present in the majority of schwannomas, whereas all GISTs were negative; some leiomyomas had weak cytoplasmic positivity. These results document distinctive patterns of intermediate filament proteins in GI mesenchymal tumors. Nestin is confirmed to be consistently expressed in GISTs but it is also present in most GI schwannomas; GFAP is helpful when separating GISTs and schwannomas, since only the latter are positive. The potential presence of K8 and K18 in GISTs should not lead to the misdiagnosis of carcinoma on biopsy.

Immunodiagnosis of childhood malignancies

Immunodiagnosis utilizing immunohistochemical techniques is currently the most commonly utilized and readily available method of ancillary diagnosis in pediatric oncopathology. The methodology comprises relatively simple steps, based on straightforward biologic concepts, and the reagents used are generally well characterized and widely used. The principle of cancer immunodiagnosis is based on the determination of neoplastic lineage using detection of proteins typical of cell differentiation pathways. Methodology sensitivity varies and has become greater with each new generation of tests, but technical draw-backs should be considered to avoid excessive background or nonspecific results. Automated instrumentation offers a degree of accuracy and reproducibility not easily attainable by manual methods.

Detection of illegal estrogen administration through immunohistochemical markers in the bovine prostate

The immunodetection of diverse cell markers was evaluated in prostatic samples from bullocks, and bullocks showing epithelial hyperplasia-metaplasia, with oestrogen-induced changes, and in experimental samples from bullocks inoculated with dietylstilbestrol (DES). Antigen-retrieval procedures allowed the use of tissues that had been fixed in formalin for long periods. Three tissue markers were chosen for the study: cytokeratins 13 and 16, vimentin and desmin. Monoclonal antibody K8.12 (specific for cytokeratins 13 and 16) stained basal cells and hyperplastic-metaplastic epithelium; monoclonal antivimentin, and desmin, allowed the definition of fibromuscular changes.

Intraosseous epithelioid hemangioendothelioma of the mandible: a case report with an immunohistochemical study

Epithelioid hemangioma is the prototype of a group of vascular tumors characterized by epithelioid endothelial cells. Hemangioendothelioma of bone is a rare lesion that constitutes less than 0.5% of primary malignant skeletal tumors. We report and discuss a case of epithelioid hemangioendothelioma arising intraosseously in the anterior portion of the mandible in a 76-year-old woman. The case was treated successfully by wide resection. Radiographically, the tumor mass showed osteolysis and expansion. Histologically, the tumor showed invasive and destructive growth, although it lacked frequent mitotic figures and severe atypia. On immunohistochemical study, tumor cells exhibited characteristics of mesenchymal and endothelial origin, i.e., strong to moderate immune reactivity against vimentin, factor VIII-related antigen (F8RA), Ulex europaeus agglutinin type 1 lectin (UEA-1), and CD 34, but not against keratin, epithelial membrane antigen (EMA) or S-100 protein (S100). The proliferating cell nuclear antigen (PCNA)-positive cell index was 27.5%. These pathological findings suggested a borderline malignant potential for this tumor. Thus, clinically, wide resection with or without dissection of regional lymph nodes is recommended.

Testicular juvenile granulosa cell and Sertoli cell tumours: a clinicopathological study of 29 cases from the Kiel Paediatric Tumour Registry

Testicular Sertoli cell tumours (SCT) and juvenile granulosa cell tumours (JGCT) are rare in childhood. This study was designed to investigate the clinical picture, morphology and disease course in a comparatively large series of cases (total number = 29). Of 198 cases of childhood testicular tumour documented in the Kiel Paediatric Tumour Registry 18 were cases of infantile SCT (9.1%) and 11 of JGCT (5.6%). The average age at the time of diagnosis was 4.2 months for infantile SCT and 0.4 months for IGCT. SCT and JGCT often showed infiltrative growth into adjacent testicular tissue, dense cellularity and considerable proliferation activity. Immunohistochemically all cases expressed vimentin intermediate filaments in both tumour types. Next in frequency of expression were cytokeratins (SCT: 7/16; JGCT: 7/10) and smooth-muscle actin (SCT: 9/15; JGCT: 4/10). Follow-up studies (24/29) showed that in cases of tumour manifestation in infancy and after complete tumour removal (usually orchiectomy) no local recurrences and no metastases occurred. The most important conclusion for diagnosis and therapy is that despite infiltrative growth, incomplete differentiation, dense cellularity and considerable proliferation activity, after surgical excision infantile SCT and JGCT have a good prognosis. Adjuvant chemotherapy or more extensive operations with lymphadenectomy are thus not indicated.

Reactivity of tissue-specific antigens in N-methyl-N'-nitro-N-nitrosoguanidine-induced neoplasms and normal tissues from medaka (Oryzias latipes)

To further characterize the distribution of tissue-specific antigens in fish neoplasms, juvenile medaka were exposed to 30 mg/L of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) for 1 hr and allowed to grow out for up to 16 mo. Using a streptavidin peroxidase technique, keratin, vimentin, and neurofilament intermediate filament proteins, and actin and S-100 proteins were labeled in MNNG-induced neoplasms and normal medaka tissues using specific monoclonal or polyclonal antibodies. In vascular tumors, rhabdomyosarcoma, and teratoma, muscle tissues were positive for actin. Other sarcomas including hemangiopericytoma, fascial sarcoma, and undifferentiated sarcoma were negative for all antibodies tested. An unusual scale-associated neoplasm, composed of clusters of scale-forming cells surrounding spicules of scale, had keratin-positive stroma. The epithelial neoplasms were also positive for keratin, except for pancreatic acinar carcinoma, which had limited positivity. Both teratoma and olfactory carcinoma had S-100-positive intraepithelial cells morphologically reminiscent of neurosensory epithelial cells, which were S-100 positive in normal tissues. Although positive reactivity in fish tissues correlated with mammalian data, the antibodies used were raised against mammalian antigens. Therefore, a negative reaction may be indicative of lack of antibody sensitivity to specific fish antigens rather than absence of the antigen in the tissues. However, these data show that tissue-specific antigen detection may assist in elucidating the biology of neoplasia in fish.

Expression of vimentin, cytokeratin, and desmin in Sertoli cells of human fetal, cryptorchid, and tumour-adjacent testicular tissue

The intermediate filament of mature human Sertoli cells is vimentin. A co-expression of vimentin together with cytokeratin has been demonstrated in Sertoli cells during embryonal development and under pathologic conditions in adult testes. We analysed the presence of vimentin, cytokeratin, and desmin in Sertoli cells of fetal testes (n=20), in seminiferous tubules of cryptorchid testes (n=10) and adjacent to testicular germ cell tumours (n=47) using specific monoclonal antibodies and single and double-labelling immunohistochemistry. During embryonal development prominent cytokeratin expression disappears after the 20th week of gestation. Interestingly, we also found desmin in immature intratubular Sertoli cells between weeks 11 and 14. In adult cryptorchid testes and in peritumour tubules, desmin was also prominently present in Sertoli cells in the vast majority of the cases investigated, as well as vimentin and cytokeratin co-expression. This first description of desmin immunoreactivity may shed some light on the ontogeny of human Sertoli cells and demonstrates that this cell type is able to express three types of intermediate filaments in a complex manner.

Intermediate filament expression and lectin histochemical features of canine transmissible venereal tumour

Immunocharacterization of intermediate filament proteins and lectin-binding studies were carried out in canine transmissible venereal tumour (TVT), a unique neoplasia sharing some epidemiological features with Kaposi's sarcoma in humans. Neoplastic cells express vimentin, but neither cytokeratin nor desmin. Regarding lectins, TVT cells express receptors for Triticum vulgaris (WGA), Concanavalia ensiformis (Con A) and Ricinus communis I (RCA-I). They appear to be negative for Ulex europaeus-I (UEA-I), Arachis hypogaea (PNA), Glycine maximus (SBA) and Dolichos biflorus (DBA).

Dermatofibroma: superficial fibrous proliferation with reactive histiocytes. A multiple immunostaining analysis

BACKGROUND

Dermatofibroma (DF) is a superficial form of benign fibrous histiocytoma, composed of a mixture of fibroblastic cells and histiocytic cells. The histogenesis of this lesion is a matter of controversy.

METHODS

Forty-five cases of DF were investigated by single and multiple immunostaining techniques, using panel of 12 antibodies including proliferating cell nuclear antigen (PCNA), vimentin, and macrophage/histiocyte markers (HAM56 and CD68).

RESULTS

Double immunostaining demonstrated that 58% of the DF cells simultaneously expressed PCNA and vimentin, whereas only 5% were PCNA+/HAM56+, and 2% were PCNA+/CD68+. By triple-stain for PCNA, vimentin, and HAM56, 56% of the DF cells were PCNA+/vimentin+/HAM56-, but only a few cells were PCNA+/HAM56+/vimentin+/-. Of the PCNA positive cells, 88% were vimentin+HAM56- and 10% were HAM56+ vimentin-/+. The cells positive for CD68 showed similar distribution to that of HAM56+ cells, though there were fewer of the former than the latter in most cases. These results suggest that the majority of the proliferating cells in DF express vimentin but not histiocytic markers. Morphologically, the PCNA+/vimentin+/HAM56- (or CD68-) cells exhibited a spindle-shaped configuration resembling fibroblasts, whereas most of the HAM56+/CD68+ cells possessed abundant rounded cytoplasm and were similar to normal histiocytes.

CONCLUSIONS

The present study suggests that the proliferative compartment of DF cells is composed chiefly of mesenchymal/fibroblastic lineage, accompanied by varying numbers of normal reactive histiocytes.

Double immunoenzymatic labelling of intermediate filaments in bovine urinary bladder tumours

Double immunoenzymatic labelling made possible the simultaneous staining of two antigens with a mixture of polyclonal and monoclonal commercial antibodies. Immunocharacterization of intermediate filament proteins was found to be an accurate indicator of histogenesis in urinary bladder tumours of cattle.

Angiomyolipoma of the nasal cavity: case report and review of the literature

An unusual localization of intranasal angiomyolipoma is described in an adult male patient with no signs of tuberous sclerosis. The lesion was composed of mature fat cells, vascular spaces with lack of elastic tissue, and presence of bundles of mature smooth muscle cells. Antibodies to intermediate filaments revealed presence of vimentin and absence of desmin in both smooth muscle bundles and in vessel walls. A review of the literature has shown that this is only the third reported case of the angiomyolipoma of the nasal cavity, and some important differences between this entity and renal angiomyolipoma are described.

Biochemical and immunocytochemical analysis in chronic proximal spinal muscular atrophy

Immunocytochemical and biochemical analyses were carried out on patients affected by chronic SMA. Three groups of patients were identified. In group I, the muscle presented a fascicular atrophy; a high percentage of atrophic type II fibers; and fibers expressing fast, slow, embryonic, and fetal myosin isoforms. In group II, the muscle was characterized by atrophic fibers and normal/hypertrophic fibers expressing only slow myosin isoforms. In group III, the muscle was characterized by fiber type grouping and fibers coexpressing fast and slow myosin isoforms but never embryonic or fetal MHC isoforms. The muscles of groups I and III contained both fast and slow myosins whereas group II muscles were predominantly slow by immunocytochemical analysis or only slow by biochemical analysis. In view of these results, immunocytochemical and histochemical analyses could help to classify chronic SMA and help to understand the different pathogenic processes which seem to be related to the maturational stage of the muscle at the age of onset of the disease.

Expression of epidermal growth factor receptor in chick embryo myocardiocytes: relation with desmin expression during cardiac development

The epidermal growth factor receptor is related with processes of cell replication and differentiation. We used the intermediate filament protein desmin as a marker to study the relation between muscle cell differentiation and modifications in the expression of this receptor during heart development in the chick embryo. Epidermal growth factor receptor was expressed as early as Hamburger and Hamilton's stage 17, when myocardiocytes are still poorly differentiated and desmin-negative. Expression became steadily weaker as the heart matured, and decreased after Hamburger and Hamilton's stage 25, a key stage in heart maturation characterized by a sharp increase in desmin expression. Our findings suggest that in the chick embryo, the expression of epidermal growth factor receptor becomes steadily weaker as myocardiocyte differentiation progresses.

Immunohistochemical detection of breast specific antigens and cytokeratins in metastatic breast carcinoma in the liver

The present study was performed to evaluate the diagnostic reliability of antibodies to breast carcinoma-specific antigen and antibodies to cytokeratin catalogue in a metastatic hepatic lesion. Immunohistochemical examinations using antibodies to gross cystic disease fluid protein-15 (GCDFP-15), BCA-225 (a glycoprotein secreted by T47D breast carcinoma cell line) and BRST-5 (a glycoprotein identified in SK-BR-7 breast carcinoma cell line), anti-cytokeratin monoclonal antibodies of MA904, AE3, CAM5.2, PKK1 and cytokeratin 19, and polyclonal anti-keratin antibodies were done. These were on 15 cases of primary breast carcinoma, eight cases of metastatic breast carcinoma in the liver, five cases of cholangiocarcinoma, eight cases of hepatocellular carcinoma and 11 cases of metastatic adenocarcinoma of another primary tumor in the liver. Results showed that GCDFP-15 antigen was most reliable: it was 100% positive in both primary and metastatic breast carcinomas unrelated to histological subtypes, and 100% negative in primary or other metastatic carcinomas in the liver. BCA-225 antigen was detected in high amounts in breast carcinomas (100%, 23/23), but it was positive in cholangiocarcinomas (80%, 4/5) and another metastatic carcinoma in the liver (64%, 7/11). BRST-5 was specifically positive in breast carcinomas but the positivity was low (13%, 3/23). Cytokeratin 19 and keratin were useful to discriminate hepatocellular carcinomas (0%, 0/8) from breast carcinomas (87%, 20/23; 96%, 22/23), but they were also positive in cholangiocarcinomas (100%, 5/5) and other metastatic carcinomas in the liver (91%, 10/11).(ABSTRACT TRUNCATED AT 250 WORDS)

Plexiform schwannoma. Immunohistochemistry of Schwann cell markers, intermediate filaments and extracellular matrix components

An immunohistochemical study using a comprehensive panel of antibodies to Schwann cell markers, intermediate filaments and extracellular matrix components has been performed on three cases of plexiform schwannoma. All tumour cells expressed S 100 protein, Leu 7-HNK 1 antigen and vimentin; glial fibrillary acidic protein was detected in many tumour cells. In addition, expression of cytokeratin was also demonstrated in one case. The associated extracellular matrix was found to be reactive with antibodies to laminin, heparan sulfate proteoglycan, fibronectin, type I, III, IV and VI collagen. It is concluded that Schwann cells producing their own extracellular matrix are the main components of these tumours. The significance of the cytokeratin expression and the possible role of the extracellular matrix in regulating Schwann cells' proliferation in peripheral nerve tumours are discussed.

NTera 2 cells: a human cell line which displays characteristics expected of a human committed neuronal progenitor cell

We have identified a human cell line with a phenotype resembling committed CNS neuronal precursor cells. NTera 2/cl.D1 (NT2/D1) cells expressed nestin and vimentin, intermediate filament (IF) proteins expressed in neuroepithelial precursor cells, as well as MAP1b, a microtubule-associated protein (MAP) expressed in human neuroepithelium. NT2/D1 cells also expressed the cell adhesion molecules NCAM and N-cadherin which are thought to be important in cell-cell interactions within the neuroepithelium. These NT2/D1 cells also expressed small amounts of NF-L, alpha-internexin, NF-M, and MAP2c, indicating that they are committed to a neuronal fate. Previous studies have shown that, following RA treatment, a proportion of NT2/D1 cells terminally differentiate into neurons and that this occurs via an asymmetric stem cell mode of differentiation. In light of the identification of the neuroepithelial phenotype of NT2/D1 cells we decided to examine more closely the relationship of in vitro neurogenesis in NT2/D1 cells, during RA treatment to that of neurons in vivo. Three days after RA treatment, islands of NT2/D1 cells showed increased expression of neurofilament proteins and increased phosphorylation of NF-M. By 10-14 days, these cells began to resemble neurons morphologically, i.e., with rounded cell bodies and processes. These neuronal cells were clustered into clumps which rested on top of a layer of progenitor cells. In this upper layer, the neurons began to express MAP2b and tau and extinguished their expression of nestin. Recently, we developed a method for obtaining pure cultures of neurons from RA treated NT2/D1 cells. The phenotype of these postmitotic neurons is clearly dissociated from that of the untreated NT2/D1 cells. Given the data obtained in this study and the characterization of the neurons derived from NT2/D1 cells, we propose that NT2/D1 cells are a committed human neuronal precursor cell line which retains some stem cell characteristics and is capable only of terminal differentiation into neurons.

Intra-abdominal desmoplastic small cell tumor in an adolescent suggesting a neurogenic origin

A case of a desmoplastic small cell tumor of the large omentum associated with gross ascites that occurred in a male adolescent is reported. Light microscopic studies revealed that the tumor cells were small and epithelioid in nature with eosinophilic hyaline material located in the perinuclear area. They were surrounded by rich desmoplastic and myxoidal stromal bands. Immunohistochemical staining revealed globoid perinuclear positivity for desmin. Vimentin, cytokeratin (AE3, CaM 5.2), epithelial membrane antigen, tissue polypeptide antigen, neuron-specific enolase, chromogranin A, endocrine granule constituent and synaptophysin were also positive in the cytoplasm. Electron microscopy revealed whorled intermediate filaments and some dense core granules in the cytoplasm. Bundles of microtubules in the cytoplasmic process and occasional cell junctions of zonulae adherentes in the tumor cells were also observed. DNA analysis of the tumor cells showed the three-fold amplification of the N-myc gene. Although desmoplastic small cell tumors showed a heterogeneous pattern with immunohistochemical studies, it is suggested that the tumor may originate from neurogenic cells.

An immunohistochemical study of epithelial membrane antigen, cytokeratin, and vimentin in papillary thyroid carcinoma. Recognition of lethal and favorable prognostic types

METHODS

Immunoreactivity for epithelial membrane antigen (EMA), cytokeratin, and vimentin was investigated in 15 papillary thyroid carcinomas (PTC) with distant metastases, 25 PTC without distant metastases, and 34 occult PTC without distant metastases that were found incidentally at autopsy.

RESULTS

More than 50% of the tumor cells were positive for EMA in 7 (47%) of 15 PTC with distant metastases, 0 (0%) of 25 PTC without distant metastases, and 1 (3%) of 34 occult PTC. The incidence of EMA positivity in PTC with distant metastases was significantly different from that of both PTC without distant metastases and occult PTC (P < 0.001). Cytokeratin reactivity was similar in the three groups, and almost all PTC stained strongly for cytokeratin. Concerning vimentin positivity, there were no significant differences in three groups; however, PTC with distant metastases tended to stain more weakly or focally than PTC without distant metastases or occult PTC.

CONCLUSIONS

These results suggest that EMA reactivity may be a useful factor for anticipating the individual risk of distant metastasis or death from PTC at the time of initial surgical treatment.

Expression of intermediate filaments in chordomas. An immunocytochemical study of five cases

An immunocytochemical investigation has been carried out on five cases of chordoma (2 of the sacrum, 2 in the spheno-occipital bone and 1 in the parapharyngeal area) to study the expression of the 5 classes of intermediate filaments (IF): cytokeratin (CK), desmin (DES), GFAP, neurofilaments (NF) and vimentin (VIM). Our results show that constant coexpression of CK, NF and VIM does occur in chordomas, whereas DES and GFAP are not demonstrable in tumor cells. The three detected IF are invariably present in all cell types but not in intracellular vacuoles or in the extracellular mucoid substance. The pattern of immunoreactivity of chordomas appears very unique as very few other neoplasms demonstrate the simultaneous occurrence of 3 distinct IF. Only choroid plexus tumors have been shown to manifest CK-NF-VIM immunoreactivity. The complex immunophenotype of chordomas may be related to their supposed origin from the notochord which normally undergoes conspicuous changes in location and morphology during embryonal development. Such changes might require the contemporary presence of multiple IF; IF expression, in fact, is known to be related to cell function and morphology. Notochordal cells and their neoplastic counterpart may consequently express an IF pattern which reflects unique architectural and morphological variations occurring during embryonal and tumor growth. Together with the speculative value of the detection of CK, NF and VIM in chordomas, the unusual immunocytochemical pattern of these tumors might provide useful diagnostic tool in differential diagnosis.

Evolution of muscle specific proteins in Werdnig-Hoffman's disease

The pattern of expression of desmin, vimentin, titin and different myosin isoforms expressed in atrophic and hypertrophic type I and type II muscle fibers was investigated in 7 biopsies from patients of various ages all diagnosed as suffering from Werdnig-Hoffman's disease. The results revealed that there was a progressive atrophy affecting both type I and type II muscle fibers. The proportion of atrophic type II fibers increased with age. These atrophic fibers expressed predominantly fast MHC together with variable amounts of embryonic and fetal abnormal concentrations of desmin, vimentin and titin were also observed in some of these fibers. Hypertrophic type I fibers expressed exclusively slow MHC. These results are in good agreement with the hypothesis that Werdnig-Hoffman's disease is associated with a persistence of slow twitch type I motor units and a loss of phasic type II motor units. They also confirm that the atrophic fibers were frequently immature although embryonic MLC was never detected in these muscles. In addition we have demonstrated that the hypertrophic fibers were not completely normal since they frequently contained abnormal concentrations of desmin and titin at their periphery.

Primary leiomyosarcoma of bone

Four cases of primary leiomyosarcoma of bone are presented. The histology of this rare tumour has been studied with a panel of monoclonal antibodies to the intermediate filaments desmin and vimentin, and to other markers including smooth muscle actin, myosin, alpha 1-antitrypsin, alpha 1-antichymotrypsin, lysozyme, S-100 protein and cytokeratin. The tumour cells were uniformly positive for desmin, vimentin, and in one case for smooth muscle actin; all the other markers were negative. The findings have been compared with other spindle cell lesions of bone and with electron-microscopy of the tumours. Immunohistochemistry allows the histological diagnosis to be made without the need to resort to ultrastructural studies.

Immunochemistry of ethylnitrosourea-induced rat neurinomas, the RN6 neurinoma cell line and their transplantation tumors

The expression of glial fibrillary acidic protein (GFAP), vimentin, S-100 protein (S-100), HNK-1, myelin basic protein (MBP) and fibronectin was investigated immunohistochemically in 51 ethylnitrosourea (ENU)-induced neurinomas of the rat. Additionally, 90 transplantation tumors derived from ENU-induced neurinomas and the RN6 rat neurinoma cell clone were studied. Vimentin immunoreactivity was shown in 50/51 primary neurinomas and 60/90 transplantation tumors. In contrast, GFAP was expressed in only 23/51 primary tumors and in 5/90 transplantation tumors. In the RN6 neurinoma clone, vimentin and GFAP could be demonstrated both in vivo and in vitro. GFAP expression varied depending on the tumor localization, i.e., tumors of distal portions of peripheral nerves were more frequently GFAP positive than tumors of the spinal roots or of cranial nerves. The same tendency was observed for S-100. In the series of transplantation tumors S-100 and GFAP immunoreactivity decreased with increasing numbers of transplantation passages. Only individual cells in 5 primary tumors were HNK-1 positive and no MBP-immunoreactive cells were observed. Our results demonstrate that the expression of differentiation antigens in ENU-induced experimental neurinomas parallels the results reported for human neurinomas.

Immunohistochemical features of giant cell carcinoma of the lung: patterns of expression of cytokeratins, vimentin, and the mucinous glycoprotein recognized by monoclonal antibody A-80

Giant cell carcinoma of the lung (GCCL) is an uncommon and extremely aggressive variant of lung cancer. Characteristic microscopic findings include marked pleomorphism, aggregates of mononucleated or multinucleated giant cells (or both), a general lack of architectural cohesiveness, extensive necrosis, and endocytosis by the giant cells. Although the epithelial character of GCCL has been confirmed by a number of studies, controversy persists as to whether it represents a variant of poorly differentiated adenocarcinoma or of squamous carcinoma. Histochemical studies for mucosubstances have yielded variable and conflicting results. This report describes conventionally fixed and processed samples from 10 cases of GCCL studied with a panel of monoclonal antibodies (Mabs) recognizing different cytokeratin polypeptides (AE1, AE3, AE1/AE3 cocktail, and CAM 5.2), vimentin, and Mab A-80, the last of which binds to a mucinous glycoprotein associated with exocrine differentiation. All 10 cases of GCCL reacted with all cytokeratin Mabs; the extent and intensity of the reaction varied notably. All cases stained strongly and diffusely with Mab AE1 and AE1/AE3, the reaction was less extensive and weaker with CAM 5.2. Significantly, 2 cases reacted focally with Mab AE3. Nine cases reacted extensively and intensely with the vimentin Mab, often showing prominent paranuclear globular profiles. All cases reacted with Mab A-80; the reaction was often strong, but the extent was variable. Findings indicate that all GCCL are indeed cytokeratin positive but that most express polypeptides toward the low-molecular weight end of the spectrum; a small subset also expresses heavier polypeptides.(ABSTRACT TRUNCATED AT 250 WORDS)

Small cell lung carcinoma: clinicopathological, immunohistochemical, and ultrastructural study

Sixty-seven cases of small cell lung carcinoma (SCLA) in Tri-Service General Hospital (TSGH) during the past 16 years were studied. For patients with extensive stage of disease, the mean survival time and 2-year survival rate were 7.2 months and 3.1% versus 13.4 months and 16.7% for patients with limited stage. A better prognosis was obtained by treatment with a combination of intensive chemotherapy and radiotherapy. Immunohistochemical studies were performed by the peroxidase-antiperoxidase method. The positive rates in descending order were bombesin (80%), synaptophysin (74.3%), neurofilament (68.6%), neuron-specific enolase (60%), low molecular weight cytokeratin (54.3%), high molecular weight cytokeratin (25.7%), chromogranin-A (22.9%), adrenocorticotrophic hormone (0). Seven cases were examined and found to be ultrastructure; only 3 cases were found to contain neurosecretory granules. We emphasize that electron microscopy is not necessary as a routine diagnostic procedure, while light microscopy should be employed whenever possible; the immunohistochemical study should be considered within this context.

Immunocytochemical demonstration of intermediate filament proteins, S-100 protein and CEA in apocrine sweat glands and apocrine gland derived lesions of the dog

The presence of carcinoembryonic antigen (CEA), intermediate filament proteins and S-100 protein in normal and pathological canine apocrine sweat glands was investigated, using a standard immunoperoxidase technique. The normal apocrine sweat glands showed a constant immunoreactivity in all the cases studied. The cells of the acini and of the ducts only reacted with the antikeratin antibody. The myoepithelial cells reacted positively with the antisera antikeratin and anti protein S-100. Epithelial cells of apocrine cysts, sweat gland adenomas and sweat gland carcinomas showed the same immunoreaction than normal apocrine cells. Proliferating myoepithelial cells were also positive for vimentin. In two out of three adenocarcinomas a positive reaction with the anti CEA could be detected in the glandular cells. This can be due to the presence in glandular cells of CEA or of Nonspecific Crossreacting Antigen (NCA). These findings indicate that demonstration of keratin is a useful aid in the detection of apocrine gland derived lesions in the dog. Similarly, S-100 protein is a marker for myoepithelial cells. Further research is necessary to investigate the expression of CEA in canine tumours.

Immunohistochemical profile of meningiomas and their histological subtypes

Seventy-seven cases of meningioma (15 with single or multiple recurrences), selected on the basis of their histologic subtypes, and nine cases of neurilemoma were analyzed immunohistochemically for the presence of the five classes of intermediate filament proteins, neuron-specific enolase (NSE), protein S-100, epithelial membrane antigen (EMA), and HNK-1 (Leu-7). Most antibodies were studied with the alkaline phosphatase-antialkaline phosphatase method. The peroxidase-anti-peroxidase and avidin-biotin-complex methods were used for Leu-7 and NSE, respectively. Meningiomas were subdivided into groups showing cytokeratin or protein S-100 positivity. Coexpression of these two markers was rare (5%) and occurred in meningotheliomatous meningiomas only. Only in these cases was cytokeratin expression more frequent than in meningiomas taken together (33% versus 20%). In contrast, protein S-100 expression was less frequent (46% versus 60% on average). In fibrous meningiomas, both cytokeratins and NSE were expressed less frequently than on average (11% versus 20%, 67% versus 88%, respectively). Protein S-100 occurred in a higher percentage of cases. Transitional meningiomas did not show cytokeratin expression. Protein S-100 occurred in a higher percentage of cases. Transitional meningiomas did not show cytokeratin expression. Protein S-100 was expressed slightly more often than in the other subtypes. Psam-momatous meningiomas coexpressed more markers than any other subtype. Hemangioblastic and hemangiopericytic forms did not stain for EMA, but otherwise showed a staining profile similar to that of meningiomas. HNK-1 was expressed in 29% of meningiomas, particularly among tumors with anaplastic histologic features. There was no marker that retrospectively indicated impending recurrences.

Expression of intermediate filaments in malignant fibrous histiocytomas

The expression of intermediate filaments (IFs) in 34 malignant fibrous histiocytomas (MFHs) was studied immunohistochemically and ultrastructurally. Using the avidin-biotin-peroxidase method, positive reactions were detected as follows: for desmin in 12 tumors, for neurofilament in two tumors, for cytokeratin in one tumor, and for vimentin in 30 tumors. Desmin immunoreactivity was found in tumors of all four histologic subtypes and cytokeratin immunoreactivity was found in one tumor of the myxoid type. Because of the cross-reactivity of anti-neurofilament antibody with reactive histiocytes, the immunoreactivity for neurofilament seemed to be non-specific. Ultrastructurally, five of 13 tumors studied contained some tumor cells showing myofibroblastic or smooth muscle cell differentiation. A few tumor cells in one cytokeratin-positive tumor had tonofilaments in their cytoplasm. Desmin expression in some MFHs seemed to be due to myofibroblastic or smooth muscle cell differentiation of some tumor cells. Cytokeratin expression seemed to indicate epithelial differentiation in some MFHs. This varied expression of IFs in MFHs may reflect the heterogeneous nature of MFHs, and suggests that MFHs represent the final stages of dedifferentiation of several different types of sarcomas or, alternatively, represent forms of poorly differentiated sarcoma with the potential of developing into more differentiated sarcomas of heterogeneous origin.

Intermediate and fine filaments of vascular leiomyomas (angiomyoma), leiomyoma and leiomyosarcomas of large veins

The expression of fine and intermediate filaments in 10 cases of leiomyosarcoma originating from a large vein, 9 cases of vascular leiomyoma (angiomyoma) and one case of a leiomyoma originating from the wall of the saphena magna vein was studied immunohistochemically by using 6 different anti-desmin antibodies, one anti-vimentin antibody and 2 antibodies to muscle-specific isoforms of actin. All the benign tumors and all the leiomyosarcomas of a large vein as well as the vein of origin were positively stained for desmin. The staining results obtained using the different anti-desmin antibodies varied considerably, however, and formaldehyde-fixed tissues were apparently inappropriate for some of them. No single anti-desmin antibody produced a positivity in all cases, and the extent and distribution of the positivity varied by being irregular and patchy in the leiomyosarcomas and in the muscle walls of the veins, while the benign tumors generally revealed a more uniform and strong positivity. Antibodies to muscle-specific and smooth muscle-specific actin produced a positive staining in all the benign tumors, as well as all the leiomyosarcomas and the veins from which they originated. A strong and uniform positivity was observed in the benign tumors and muscle walls of the veins, while the positivity in the leiomyosarcomas was more irregular, as it was for desmin. Vimentin was constantly expressed in the benign tumors and in the veins of origin, but only in 5/10 of the leiomyosarcomas. It is concluded from this study that the immunohistochemical demonstration of desmin, utilizing a monoclonal antibody appropriate to the type of fixation used, and muscle specific isoforms of actin, provide strong support to the light-microscopic diagnosis of leiomyosarcoma of venous origin.

Immunostaining of intermediate filament proteins in paraffin sections. Evaluation of optimal protease treatment to improve the immunoreactivity

Different protocols of protease (pepsin) treatment were compared in the immunostaining for intermediate filament (IF) proteins in formaldehyde-fixed and paraffin-embedded tissues. Without protease treatment, the immunoreactivity for all IF proteins was poor in such material. Appropriate pepsin pretreatment improved the immunoreactivity of formaldehyde-fixed tissues for all types of IF proteins, except for the 68 K neurofilament protein, which could not be immunostained with the antibody used. The optimal time for the pepsin treatment was varying in different tissues, and too long treatment caused progressive loss of immunostaining. Thus, for instance when demonstrating cytokeratins, renal adenocarcinomas were more sensitive to protease and needed a shorter treatment than other carcinomas. Therefore, a nonoptimal protease treatment protocol may cause false negative results and false cell type selective IF immunostaining. Prolonged fixation made it necessary to prolong the protease treatment. In tissues fixed up to four years in formalin, cytokeratin immunoreactivity could still be restored by a long pepsin treatment (up to 2-3 hours). For most tissues fixed for 24 hours in formaldehyde, an optimal protocol was the following: 0.05% pepsin (2 U/ml) in HCl, pH 1.8, at +37 degrees C for 20-30 minutes. The protease treatment did not produce false positive results. Alcohol-fixed material was good for IF immunostaining without any protease treatment, but such tissue blocks mostly lost the immunoreactivity during long term storage.

Cervical thymic cysts

Four cases of cervical thymic cyst are described. Clinical and microscopic appearances are reviewed, with reference to its distinction from branchial cyst. The use of monoclonal antibodies to cytokeratin as a histologic aid to diagnosis is discussed.

Papillary serous cystadenoma of the testis

A case is presented of a 50-year old man with a unilocular cystic intratesticular tumour exhibiting the morphological features demanded from WHO for the diagnosis of serous papillary cystadenoma of the ovary. Keratin filaments could be demonstrated in the cyst lining and papillae covering cells by means of PAP-technique; AFP and SP-1 were lacking. The epithelial cells of the tumour showed a lectin binding pattern (WGA, UEA-I, PNA, Con A, PSA, LCA, RCA) different from the epithelium of rete testis and epididymis. We intend to classify our tumour as the male analogue of the respective ovarian growth.

An immunohistochemical study of cytokeratin and vimentin in benign and malignant thyroid lesions

Intermediate filaments in benign and malignant thyroid lesions were immunohistochemically studied using polyclonal and monoclonal anti-cytokeratin (CK), and monoclonal anti-vimentin antibodies. Antigenicity of CK and vimentin was almost completely destroyed during formalin fixation in normal thyroid and all thyroid lesions except for some cases of papillary and squamous cell carcinoma, although the latter showed negative immunostaining with anti-vimentin antibody. In sections fixed with Carnoy's fixative, most cases of papillary carcinoma showed an intense reaction product for polyclonal anti-CK, monoclonal anti-CK-7, CK-19 and anti-vimentin antibodies. The reaction product for anti-CK antibodies was located mainly in the apical cytoplasm and that for anti-vimentin antibody in the basal cytoplasm. However antigenicity was still destroyed by the fixative in many specimens of normal thyroid, benign thyroid lesions and follicular carcinoma. In frozen sections, all specimens showed preserved antigenicity for both antigens with an intense reaction product in papillary carcinoma, but this was weaker in normal thyroid, benign thyroid lesions and follicular carcinoma. Therefore, follicular cells under normal and pathological conditions contain intermediate filaments of CK and vimentin in their cytoplasm and co-expression of the antigens is significantly increased in papillary carcinoma.

Histopathological and immunohistochemical analysis of lung tumors: description of a convenient technique for use with fine needle biopsy

In this paper we describe a convenient procedure for use with fine-needle biopsy in the diagnosis of lung and medistinal tumors. Cells obtained from a fine-needle aspiration are suspended in a formaldehyde solution and allowed to sediment onto a polycarbonate filter, using a filtering device specially designed for this purpose. The filter with the aspirated cells is then embedded in paraffin and thereafter sectioned and stained in a routine manner. The main advantages with this technique, instead of cytology, are: 1. the cells are kept mainly intact, mostly in undisrupted clusters, and this increases the possibility of obtaining a specific diagnosis, a prerequisite for the diversified clinical management of malignant tumors: 2. possibilities exist, when necessary, of further immunohistochemical characterization of tumor cells in order to obtain a specific diagnosis without thoractomy. This could be of major importance when the management of certain tumors and infiltrates (i.e. those preferably treated by radio- and chemotherapy) does not require surgical intervention.

Diagnosis of major tumor categories in fine-needle aspirates is more accurate when light microscopy is combined with intermediate filament typing. A study of 403 cases

Intermediate filament (IF) typing of tumor cells with monoclonal antibodies was applied to 403 fine-needle aspirates. In 271 cases specific cytologic diagnosis of tumor type was apparent from clinical data and light microscopic study alone. Intermediate filament typing confirmed the tumor type in 262 cases and changed an erroneous cytologic diagnosis of major tumor type in nine cases. In a second group of 132 difficult cases, where the tumor type could not be revealed with certainty, IF typing confirmed the cytologic suggestion of tumor type in 50 cases, changed it in nine cases, and helped resolve ambiguities in cytologic diagnosis in 59 cases. It did not help in 14 cases. Thus IF typing adds independent objective differentiation specific information to descriptive tumor typing currently used in aspiration cytologic study. When combined with the morphologic analysis of tumor cells and clinical information it can refine the cytologic diagnosis of major tumor types and prevent error.

Expression of vimentin and glial fibrillary acidic protein in ethylnitrosourea-induced rat gliomas and glioma cell lines

The expression of glial fibrillary acidic protein (GFAP) and vimentin was investigated immunohistochemically in 104 experimental gliomas induced by transplancental application of ethylnitrosourea (ENU) in CDF rats. Immunoreactivity for vimentin was prominent in many astrocytic tumor cells and especially in small glioma cells forming anaplastic medulloblastoma-like foci in many tumors. The majority of tumor cells in oligodendroglial tumors were vimentin negative, except for some of the large polymorphous oligodendrogliomas which contained intermingled vimentin positive glioma cells. GFAP immunoreactivity was detectable only in a low fraction of tumor astrocytes and in a few exceptional cases some oligodendroglial tumor cells stained positive. Immunohistochemistry with antibodies against neurofilaments and cytokeratins revealed no staining in tumor cells of ENU-induced gliomas, while all oligodendrogliomatous tumors stained positive for HNK-1. Immunocytological and immunoblot investigations of the two rat glioma cell clones RG2 and F98, which are both derived from ENU-induced gliomas, showed a prominent expression of vimentin in monolayer cultures and in syngeneic intracerebral transplantation tumors. F98 additionally demonstrated a fraction of GFAP positive cells especially in confluent cultures and in intracerebral tumors. RG2, on the other hand, exhibited virtually no GFAP immunoreactivity in culture but showed individual GFAP positive tumor cells in intracerebral tumors. Our results revealed a more precise picture of the cellular differentiation in ENU-induced rat gliomas and in two widely used glioma cell lines. They underline the heterogeneity of experimental rat gliomas which may comprise cells at different stages of differentiation towards oligodendroglial or astroglial phenotype.

Cytokeratin expression in experimental murine rhabdomyosarcomas. Intermediate filament pattern in original tumors, allotransplants, cell culture and re-established tumors from cell culture

Soft tissue sarcomas were induced by 20-methylcholanthrene in NMRI-mice. The tumors were characterized as rhabdomyosarcomas by light and electron microscopy as well as immunohistochemistry (vimentin, desmin and myoglobin expression). Cytokeratins could be demonstrated by a panel of different poly- and monoclonal antibodies in original rhabdomyosarcomas, their allotransplants and the re-established tumors from cell culture in nude mice. The cytokeratin positive tumor cells were arranged in small clusters and/or haphazardly single dispersed in the rhabdomyosarcomas. By means of monoclonal antibodies cytokeratins No. 8 and No. 19 could be evidenced and cytokeratin No. 18 could be made probably. Behind the background of cytokeratin expression in developing fetal cross striated muscle cells our findings are discussed as a reminiscence of embryonal muscle development in these tumors. The significance of cytokeratin expression in rhabdomyosarcomas for diagnostic histopathology is emphasized.