Expression of a neural type of intermediate filament as a distinguishing feature between oat cell carcinoma and other lung cancers.

Expression of intermediate filaments was studied immunohistologically in oat-cell (6 cases), epidermoid (9 cases), adeno- (7 cases), large-cell anaplastic (3 cases), and bronchioalveolar carcinoma (3 cases), of lung. Affinity-purified antibodies against epithelial (anti-keratin), neural (anti-neurofilament), muscle (anti-desmin) and mesenchymal (anti-vimentin) intermediate filaments were used. In indirect immunofluorescence microscopy of oat-cell carcinomas a positive cytoplasmic fluorescence was seen only with antibodies against neural intermediate filaments, neurofilaments, while no staining of the tumor cells was observed with antibodies against other types of intermediate filaments. On the other hand, all the epidermoid, adeno, anaplastic, and bronchioalveolar carcinomas showed constantly a strong reaction with anti-keratin antibodies in a varying number of cells but no decoration with anti-neurofilament antibodies. The results show that expression of neural intermediate filaments is a major distinguishing feature between oat-cell carcinomas and other lung cancers and suggest that anti-neurofilament antibodies can be used as a diagnostic aid in the surgical pathologic study of pulmonary neoplasms.     

Antidesmosomal monoclonal antibody in the diagnosis of intracranial tumours

Immunocytochemistry has been applied extensively to the diagnosis of intracranial tumours, but meningiomas still present a diagnostic problem. However, desmosomes have been shown by electron microscopy to be present in meningiomas, and this distinguishes them from gliomas. This paper describes a new monoclonal antibody, 11-5F, against desmosomal proteins 1 and 2 (desmoplakins) and assesses its usefulness in the diagnosis of meningiomas and other intracranial tumours. A total of 74 surgically removed intracranial tumours were examined by fluorescent antibody staining with 11-5F on frozen sections. In addition, a panel of antibodies against cytokeratin, vimentin, glial fibrillary acidic protein, and S100 protein was used. 11-5F stained 30/30 meningiomas and 14/14 metastatic carcinomas but 0/30 gliomas, thus distinguishing meningiomas and metastatic carcinomas from gliomas. The distinction between meningiomas and metastatic carcinomas on the basis of intermediate filaments staining was more difficult because neither the anticytokeratin nor the antivimentin antibody was specific for either tumour type. This study emphasizes the value of antidesmosomal antibodies as an important adjunct to the diagnosis of intracranial tumours.     

Antibodies to intermediate filament proteins as molecular markers in clinical tumor pathology. Differentiation of carcinomas by their reaction with different cytokeratin antibodies

Antibodies to human and bovine epidermal prekeratin and antibodies to mouse liver cytokeratin component D (Mr 49 000) have been applied in indirect immunofluorescence microscopy on sections of human tumors of mammary gland and liver. In non-neoplastic mammary gland all epithelial cells were stained with these antibodies. In pre-invasive and invasive ductal and lobular carcinomas a cell population was observed which was not significantly stained with antibodies to epidermal prekeratin but did strongly react with antibodies to liver cytokeratin D. In the liver, the antibodies to epidermal prekeratin as well as those directed against liver cytokeratin D strongly decorated bile duct epithelia. In contrast, significant staining of the hepatocytes was only achieved with antibodies to liver cytokeratin D. This different staining reaction was maintained in liver tumors of hepatocellular and cholangiocellular origin. Antibodies to vimentin stained mesenchymal cells and tumors of mesenchymal derivation but reacted not significantly with any of the epithelial and carcinoma cells examined. The difference is of practical importance for the discrimination between anaplastic carcinomas and sarcomas of unknown origin. Cytokeratin could also be detected by antibody staining using the peroxidase-antiperoxidase (PAP) technique in formaldehyde-fixed and paraffin-embedded material of skin, gastrointestinal, respiratory, urinary and genital tract as well as various glands, liver and kidney. Examples of positive reactions were shown in a squamous cell carcinoma, a basalioma and a pleomorphic adenoma of the parotis. It is concluded that the immunohistochemical analysis of intermediate filament proteins has diagnostic potential in clinical pathology and may help to elucidate histogenesis and differentiation of tumors and possibly also prognosis of tumor growth. It is further suggested to use antibodies recognizing different subsets of proteins of the cytokeratin family in order to distinguish between different types of carcinomas.     

Epidermal growth factor receptors in lung tumours

Immunocytochemical analysis of epidermal growth factor (EGF) receptor expression was carried out on frozen sections of 109 primary lung tumours resected at the Brompton Hospital from February 1984 to May 1985. Tumours with detectable levels of this proto-oncogene protein were significantly more frequent among squamous cell carcinomas than among other types of lung tumour. No truncated EGF receptors were detected in the tumours using two monoclonal antibodies (Mabs) directed against different portions of the receptor (EGFR1 and F4). Mab F4 is the first antibody to the EGF receptor to show reactivity in paraffin sections. Southern blot analysis of a subset of the tumours detected amplification of the EGF receptor gene in squamous cell carcinomas but not in adenocarcinomas. The one carcinosarcoma examined had a re-arranged and amplified EGF receptor gene. Measurement of EGF receptor expression in lung tumours can be of diagnostic value and may prove to be useful in the development of antibody-directed therapy.     

Cytokeratin 20 in human carcinomas. A new histodiagnostic marker detected by monoclonal antibodies.

The authors have recently identified a new cytokeratin (CK) polypeptide, CK 20, whose expression is almost entirely confined to the gastric and intestinal epithelium, urothelium, and Merkel cells. Seven monoclonal antibodies (MAbs) specific for CK 20 were raised and characterized by applying immunoblotting and immunocytochemical screening. All of them reacted on frozen tissue sections. A further MAb, IT-Ks20.8, recognized CK 20 in sections of formalin-fixed, paraffin-embedded tissue samples. A total of 711 cases of primary and metastatic cancer, mostly carcinomas, were analyzed immunohistochemically for CK-20 expression, using CK-20 specific guinea-pig antibodies and MAbs. The expression spectrum of CK 20 in carcinomas resembled that seen in the corresponding normal epithelia of origin. CK-20 positivity was seen in the vast majority of adenocarcinomas of the colon (89/93 cases), mucinous ovarian tumors, transitional-cell and Merkel-cell carcinomas and frequently also in adenocarcinomas of the stomach, bile system, and pancreas. Most squamous cell carcinomas in general and most adenocarcinomas from other sites (breast, lung, endometrium), nonmucinous tumors of the ovary, and small-cell lung carcinomas were essentially or completely negative. The authors propose to use CK 20 as a diagnostic marker valuable in distinguishing different types of carcinomas, notably when presenting as metastases.     

Expression of cytokeratins and vimentin in epithelial cells of normal and pathologic thyroid tissue

Summary The presence of intermediate filament proteins of the cytokeratin and vimentin type was evaluated in normal and pathologically changed thyroid tissue specimens. Using the indirect immunoperoxidase technique with 4 different cytokeratin monoclonal antibodies: RCK114 (broad spectred), K2080 (broad spectred), RGE53 (directed against component 18, present in simple epithelium) and RKSE60 (directed against component 10, associated with keratinization). Co-expression of cytokeratin and vimentin was evaluated with a double immunoenzyme staining technique.The results indicate that normal and transformed cells express cytokeratins of the non-epidermal type. Cytokeratins of the epidermal type are sometimes present in carcinomas. They do not differentiate in tumour type (i.e. papillary, follicular, anaplastic or medullary carcinoma).The co-expression of cytokeratins and vimentin is not restricted to carcinomas: in a small percentage of cases it is also present in normal epithelial cells of the thyroid gland. Moreover, the distribution pattern of cytokeratins and vimentin within the cell is changed in malignant transformed epithelial cells of the gland and seems to be inversely related to the degree of differentiation of these cells. The implications of our findings for the possible use of cytokeratins and vimentin in diagnostic pathology are discussed.     

Immunohistochemical study of anaplastic meningioma with special reference to the phenotypic change of intermediate filament protein

The phenotypic changes in the transformation of classic or atypical meningioma to anaplastic meningioma were investigated. Among nine patients with anaplastic meningioma, four men and five women ranging in age from 32 to 75 years, four cases were identified as anaplastic meningioma at the first operation (de novo type), while five cases were identified as classic or atypical meningioma at the first operation but at recurrence had transformed to anaplastic meningioma (secondary type). Immunohistochemical analysis was performed with the avidin-biotin complex method using monoclonal antibodies for glial fibrillary acidic protein, cytokeratin, alpha-internexin, neurofilament proteins (70 kd, 168 kd, and 200 kd), desmin, vimentin, CD34, Ki-67, epithelial membrane antigen, and S-100 protein. Immunohistochemical analysis showed positive immunoreactivity for cytokeratin, alpha-internexin, neurofilament proteins, vimentin, and glial fibrillary acidic protein during the course of progression. Expression of epithelial membrane antigen decreased with malignant progression. Marked expression of cytokeratin was observed in anaplastic meningioma. Ki-67 labeling index increased at every recurrence of both the de novo and secondary types. The major phenotypic changes in the transformation of meningioma from the classic to the anaplastic type are loss of meningioma architecture, decreased expression of epithelial membrane antigen, increased expression of vimentin, and metaplastic expression of alpha-internexin and neurofilament triplet proteins.     

The intermediate filament cytoskeleton of cutaneous neuroendocrine carcinoma (Merkel cell tumour)

Summary The presence and distribution of cytokeratins, neurofilament proteins, vimentin and glial fibrillary acidic protein were studied in 10 cutaneous neuroendocrine carcinomas (CNEC) by immunohistochemical techniques, using specific antibodies. In all cases tumour cells were specifically stained with antibodies to mouse liver cytokeratin component D in paraffin-embedded formalin-fixed and frozen sections. Moreover, one- and two-dimensional SDS-polyacrylamide gel electrophoresis of high salt/detergent resistant cytoskeletal residues from tumour material, isolated by microdissection from frozen sections, revealed the presence of cytokeratin components 8 and 18 which are characteristic constitutents of cytokeratin filaments of simple epithalia. Neurofilament proteins were detected by immunocytochemistry in tumour cells from 2 patients, from whom frozen material was available, and their presence was also positively identified in cytoskeletal residues by immunoblotting using specific antibodies. Glial fibrillary acidic protein and vimentin could not be demonstrated in tumour cells. Our studies did not confirm the suggested origin of CNEC from epidermal Merkel cells.This work was supported in part by Fonds zur Förderung der wissenschaftlichen Forschung, Grant P4708 to H.D.     

Use of immunohistochemical staining panel for characterisation of ovarian neoplasms.

Eighty five ovarian epithelial and non-epithelial tumours were studied by peroxidase histochemical staining for their reactivity with six monoclonal human milk fat globule (HMFG) antibodies, peanut agglutinin (PNA) lectin, and a monoclonal cytokeratin antibody. HMFG IIIC12 and cytokeratin antibodies distinguished epithelial from non-epithelial tumours. The staining patterns of mucinous and serous tumours were essentially different from each other; poorly differentiated anaplastic carcinomas showed similar antigenic content to that of the serous cystadenocarcinomas. Furthermore, staining with PNA lectin and HMFG antibodies was useful in distinguishing clear cell carcinomas from other malignant epithelial tumours of the ovary.     

Are keratin proteins a better tumor marker than epithelial membrane antigen? A comparative immunohistochemical study of various paraffin-embedded neoplasms using monoclonal and polyclonal antibodies

Epithelial membrane antigen and keratin proteins represent markers of epithelial differentiation that may be detected in routine formalin-fixed, paraffin-embedded tissues. Eighty-seven neoplasms, including 48 adenocarcinomas of various types, squamous and transitional cell carcinomas, small-cell anaplastic carcinomas, carcinoid tumors, mesotheliomas, hepatomas, melanomas (metastatic), adrenal cortical carcinomas, germ cell tumors, and extramammary Paget's disease, were assessed to determine the relative effectiveness of these antigens as tumor markers. Immunoperoxidase studies were performed using monoclonal antibodies to epithelial membrane antigen and monoclonal (combined AE1 and AE3) and polyclonal (bovine muzzle keratins) antibodies to keratin proteins. In more than half the cases (50/87%), both markers yielded comparable results. However, in 29 cases (33%), keratin proteins were clearly superior to epithelial membrane antigen as a tumor cell marker. Particular discrepancies were apparent for some gastrointestinal adenocarcinomas, squamous cell carcinomas, hepatomas (hepatocellular type), spindle cell components of mesotheliomas, and carcinoid tumors. Epithelial membrane antigen represented a better marker in eight cases (9%), mainly for small-cell anaplastic carcinomas and some renal cell and pulmonary adenocarcinomas. Adrenal cortical carcinomas, melanomas, and seminomas were nonimmunoreactive for both antigens. Epithelial membrane antigen and keratin proteins represent useful complementary markers in diagnostic surgical pathology.     

Expression of intermediate filament proteins in normal and diseased thyroid glands.

A total of 67 samples from normal and pathological thyroid glands were stained (as formalin fixed paraffin sections) with a panel of monoclonal antibodies directed against intermediate filament proteins. The study confirmed previous reports of cytokeratin and vimentin coexpression in primary thyroid carcinomas, but coexpression was also detected in normal thyroid and in a range of benign conditions including follicular adenomas, Hashimoto's thyroiditis, and diffuse hyperplasia (thyrotoxicosis). Prekeratin expression was found (using antibodies recognising higher molecular weight cytokeratins) predominantly in areas of squamous change, independent of the underlying thyroid pathology. This study does not therefore support previous findings that prekeratin expression provides a reliable means of distinguishing follicular pattern papillary carcinoma from follicular carcinoma with its poorer prognosis or that it helps distinguish benign from malignant papillary lesions. No evidence of desmin or neurofilament expression was seen, and in particular, neurofilaments could not be detected in any of the cases of medullary carcinoma studied.     

Intermediate-filament expression in thyroid gland carcinomas

Summary Paraffin-embedded specimens of 200 primary thyroid carcinomas were examined immunohistologically for the expression of intermediate-filament (IF) protein of the cytokeratin, vimentin and neurofilament type. In 36 cases, snap-frozen tissue was available, and double label immunofluorescence microscopy was performed in 23 of them.Cytokeratin reactivity was found in all cells of all follicular, papillary and medullary carcinoma cases examined. Using a monoclonal vimentin antibody, positive staining was found in many, though not all cells of the papillary tumours and in approximately 50% of the follicular and the medullary carcinomas. Among anaplastic carcinomas, some tumours were positive for cytokeratins, with or without coexpression of vimentin. Neurofilaments could only be demonstrated in approximately 13% of medullary tumours which in general also exhibited vimentin positivity.The differences of IF expression in follicle and C-cell thyroid carcinomas and the broad variation of cytokeratin and vimentin immunoreactivity among anaplastic tumours of this organ is discussed in relation to the possible intrinsic heterogeneity of these tumours and the diagnostic value of these marker.Dedicated to Prof. Dr. G. Seifert on the occasion of his 65th birthday     

Keratin expression in equine normal epidermis and cutaneous papillomas using monoclonal antibodies.

Keratin expressions in normal equine epidermis and experimentally induced equine papillomas were studied by immunohistochemical methods with three different human cytokeratin monoclonal antibodies, 34 beta B4 (directed against component 1), 34 beta E12 (directed against components 1, 5, 10, 11) and 35 beta H11 (directed against component 8). Staining patterns with 34 beta B4 and 34 beta E12 in the normal equine epidermis did not differ from those in the normal human epidermis. In the early developing papilloma, keratinocytes showed an abnormal suprabasal staining pattern and expressed an additional 56 kD keratin protein detected by 34 beta E12. In the advanced papilloma, cytolytic cells in the outer spinous and the granular layers did not stain positively with any of the three antibodies used. In both early and advanced papillomas, the expression of high molecular weight keratin proteins, as detected by 34 beta B4 and 34 beta E12, did not correlate with the degree of keratinization. By electron microscopy, keratinocytes in the advanced papilloma showed a marked decrease of tonofibrils and desmosome-tonofilament complex. These alterations may result from an abnormality in both proliferation and functional terminal differentiation of keratinocytes in the papilloma. There were obvious differences in staining patterns with 35 beta H11 between the normal human and equine epidermis; 54 kD keratin protein was expressed in suprabasal layers of the equine normal and papillomatous epidermis. Thus, this keratin protein may be regarded as a "permanent" marker for the equine epidermis.     

Monoclonal antibodies with different specificities against cytokeratins. An immunohistochemical study of normal tissues and tumors.

Monoclonal antibodies against cytokeratins, isolated from human callus, were prepared. Here we describe the characterization of three of these monoclonal antibodies (Clones 77, 78, and 80) with special emphasis on the staining characteristics of a number of normal epithelial tissues and a series of tumors. On thin sections and in immunoblotting experiments our monoclonal antibodies showed different specificities. In immunoblots Clone 80 stained more bands in preparations of cytokeratin from callus, cultured keratinocytes, and a metastasis of a lung carcinoma than Clones 77 and 78. In this last cytokeratin preparation Clones 77 and 78 each stained a separate band not stained by Clone 80. In normal tissues Clone 80 stained all types of epithelia except myoepithelium and podocytes of glomeruli. Clone 78 stained mainly squamous epithelium. Clone 77 stained differentiated squamous epithelium, transitional epithelium, ductal epithelium, and parenchymatous epithelium. These results confirm the heterogeneity of cytokeratins. In neoplasms Clone 77 was positive with adenocarcinoma and squamous cell carcinoma. Clone 78 stained squamous cell carcinoma and well-differentiated adenocarcinoma. Clone 80 stained all epithelial tumors, including anaplastic carcinoma, and is therefore useful in tumor diagnosis.     

Expression of intermediate filament proteins in thyroid gland and thyroid tumors

The presence of intermediate filament proteins of cytokeratin/prekeratin type and vimentin type was evaluated in non-neoplastic thyroid glands and in different types of thyroid neoplasms. Follicular epithelium of both normal and goitrous thyroids showed a strong reaction with anticytokeratin antibodies that widely cross-react with various simple epithelia. On the other hand, in normal thyroid, there were only occasionally (in one of 12 cases) solitary cells reacting with antibodies to epidermal prekeratin. In nodular goiters, such cells were often seen (eight of 18), especially among the lining cells of cysts, and in chronic thyroiditis in all (12 of 12) cases. Only the stromal cells and intraluminal macrophages reacted with antibodies to vimentin. Neoplastic cells of papillary carcinomas showed a positive staining reaction both with antibodies to cytokeratins and to epidermal prekeratin. Follicular carcinoma cells, although positive for cytokeratins, could generally not be stained with antibodies to epidermal prekeratin. Medullary carcinoma cells also showed cytokeratin positivity and, only occasionally, positivity for epidermal prekeratin. Anaplastic carcinomas were also reactive with antibodies to cytokeratin but, for the most part, were negative for epidermal prekeratin. Interestingly, some neoplastic cells of all types of thyroid carcinomas also appeared to contain vimentin, as shown with both polyclonal and monoclonal antivimentin antibodies. In contrast to carcinomas, the intermediate filaments of thyroid sarcomas and lymphomas were only of vimentin type. Furthermore, it was found that the papillary structures in benign goiters were only reactive with cytokeratin antibodies and lacked, in contrast to papillary carcinomas, epidermal prekeratin-like immunoreactivity. Hence, the analysis of intermediate filament proteins of thyroid tumors can be utilized to differentiate between papillary and follicular carcinomas and between benign and malignant papillary lesions as well as between anaplastic thyroid carcinomas and sarcomas or lymphomas.     

Production and characterisation of an antimelanoma monoclonal antibody KBA.62 using a new melanoma cell line reactive on paraffin wax embedded sections.

AIMS--To generate new monoclonal antibodies directed against melanoma associated antigens using a new melanoma cell line, KAL. METHODS--The melanoma cell line was established in culture from a lymph node metastasis of malignant melanoma. Normal Balb/c mice were immunised with KAL cells. Splenocytes were used for fusion experiments using standard techniques. Hybridoma supernatants were tested for antibody binding activity using an indirect immunoperoxidase method on frozen sections from KAL tumour cells xenografted onto nude mice and human tonsils. KBA.62 was selected because of its reactivity with melanocytic proliferations on both frozen and paraffin wax sections. RESULTS--On immunoblotting, KBA.62 reacted with three bands of 140, 135 and 128 kD and two weak bands of 88 and 73 kD. In normal human tissues basal melanocytes in the epidermis did not react with this antibody and only occasional labelling of endothelial cells was noted. Of the human tumours, KBA.62 reacted strongly and uniformly with the majority of benign (21/21) and malignant (75/86) melanocytic proliferations. Staining was localised predominantly to the cell membrane with little or no cytoplasmic reactivity. Negative staining was observed in the majority of human non-melanocytic neoplasms, the exceptions being some carcinomas (11/89), particularly the well differentiated squamous cell type. This, however, was not thought to present a diagnostic problem. CONCLUSIONS--KBA.62 appears to be potentially useful in ascertaining the immunomorphological diagnosis of malignant melanoma in routinely processed paraffin wax sections.     

Coexpression of neuroendocrine markers and epithelial cytoskeletal proteins in bronchopulmonary neuroendocrine neoplasms

Neuroendocrine (NE) neoplasms of the human bronchopulmonary tract were examined by electron microscopy, immunocytochemistry, and gel electrophoresis of cytoskeletal proteins from microdissected tissue samples. All samples (carcinoids, well-differentiated NE carcinoma, NE carcinomas of intermediate type, NE carcinomas of the small cell type) contained significant numbers of cells that immunostained for one or more of the following neuroendocrine markers tested: bombesin, calcitonin, ACTH, leu-enkephalin, gastrin, serotonin, somatostatin, alpha-melanocyte-stimulating hormone, vasoactive intestinal peptide, glucagon, insulin, substance P, and neuron-specific enolase. Electron microscopy revealed typical NE cell features, including variable abundant and frequently heterogeneous neurosecretory granules. Tumor cells contained filaments specifically stained with different conventional and monoclonal antibodies to cytokeratins and displayed punctate plasma membrane staining with antibodies to desmoplakins, in agreement with the electron microscopic demonstration of tonofilament bundles and desmosomes. Immunocytochemistry for NE markers and cytoskeletal proteins on consecutive sections revealed both cytokeratins and neuroendocrine substances in single cells. Using gel electrophoresis of cytoskeletal proteins of tissue regions extracted with high salt buffer and detergent, we could detect, in the tumors tested, appreciable amounts of cytokeratin polypeptides 8, 18, and 19, i.e., major cytokeratins also found in certain other lung carcinomas such as adenocarcinomas. Tumor cells were not significantly stained with antibodies to other intermediate filament proteins such as vimentin, desmin, glial filament protein, and neurofilament protein. The results show that NE substances can be synthesized in cells containing a typical epithelial cytoskeleton, i.e., cytokeratin filaments and desmosomes. These findings support the notion of an epithelial character of these tumors and appear in contrast with recent reports that neurofilaments are the only type of intermediate filaments present in carcinoids and other pulmonary NE tumors. These observations may have important implications for the histogenesis of NE carcinomas and for diagnostic pathology.     

Rat antikeratin monoclonal antibodies are specific for stratified squamous epithelia

Seven monoclonal antibodies of rat origin were generated against human epidermal keratins and were assayed by immunoblot and by immunoperoxidase staining of frozen sections from various human epithelial tissues. By immunoblotting, the antibodies recognized two different subsets of high molecular weight cytokeratin polypeptides. Unlike the majority of the reported mouse monoclonal antibodies obtained to similar immunogens, these rat monoclonal antibodies showed an unexpected degree of specificity, i.e., they stained only stratified squamous epithelia and not simple epithelia nor urothelia. The potential of using rats and the appropriate immunogen to generate more tissue-specific anticytokeratin monoclonal antibodies is discussed.     

Neuroendocrine differentiation in poorly differentiated lung carcinomas: a light microscopic and immunohistologic study

Frozen, unfixed tissue sections from 56 poorly differentiated, non-small cell primary lung tumors were examined by the immunoperoxidase technique with a panel of monoclonal antibodies to neuroendocrine (chromogranin A (CGA), synaptophysin (SYN), S-100) and intermediate filament (cytokeratin, vimentin, neurofilament) antigens. Although light microscopic features of neuroendocrine (NE) differentiation were not present, staining for CGA and/or SYN was identified in 5/17 (29%) large cell carcinomas (LCC) and 4/19 (21%) poorly differentiated adenocarcinomas (PDA). Diffuse, strong SYN staining was present in two LCC and one PDA. Heterogeneous intermediate filament expression (vimentin and/or neurofilament) was frequent (LCC, 10/17 (59%); PDA, 10/19 (53%)) and accompanied NE markers in 8/9 (89%) cases. Poorly differentiated squamous carcinomas were more homogeneous, with focal SYN in only 1/20 (5%) and focal presence of intermediate filaments other than cytokeratin in only 2/20 (10%). We conclude: (a) immunohistologic evidence of NE differentiation is present in a significant proportion of pulmonary large cell and poorly differentiated adenocarcinomas and rare in poorly differentiated squamous carcinomas; (b) NE differentiation is generally accompanied by heterogeneous intermediate filament expression; (c) divergent NE differentiation is not necessarily reflected by light microscopic features.     

Cushing syndrome-associated pheochromocytoma and adrenal carcinoma. An immunohistological investigation.

Seven adrenal carcinomas and seventeen pheochromocytomas (PHs), two of which were clinically associated with a Cushing's syndrome and one associated with multiple endocrine neoplasia Type II (MEN-II), were investigated immunohistologically with a panel of antibodies against intermediate filament proteins, a proliferation-associated nuclear antigen (Ki-67), neuroendocrine tumor markers, and different hormones on paraffin-embedded tissue sections and, from 19 cases, also on frozen tissue sections. Synaptophysin proved to be the most reliable tumor cell marker on both snap-frozen and paraffin-embedded tissue but, like antibodies against NSE, yielded unspecific stainings in the carcinomas. The two Cushing-associated pheochromocytomas (CaPH) showed the same immunohistological profile as the other PHs, except one chromogranin-negative tumor. Five PHs showed weak reactivity for calcitonin, one for serotonin, and two for a-HCG in small amounts. All PHs lacked other hormone expression, including ACTH. The average growth fraction was small (2.2%) in 13 cases, but 80% of the tumor cells were proliferating in one case of CaPH. Adrenal carcinomas showed only weak or no expression of keratin in one case, a homogenous or droplet, non-filamentous cytoplasmic staining with antibodies against neurofilament in frozen tissue section, and they were completely chromogranin-negative. The average growth fraction was 7.6% in 5 cases.