Establishment and characterization of a primary effusion (body cavity-based) lymphoma cell line (BC-3) harboring kaposi's sarcoma-associated herpesvirus (KSHV/HHV-8) in the absence of Epstein-Barr virus

The recently identified Kaposi's sarcoma-associated herpesvirus (KSHV), also known as human herpesvirus 8 (HHV-8), has been found to be consistently associated with an unusual subset of acquired immunodeficiency syndrome-related lymphomas, the so-called body cavity-based lymphomas (BCBL) or primary effusion lymphomas (PEL). These lymphomas are characterized by a unique spectrum of morphologic and molecular characteristics, and grow as lymphomatous effusions without an identifiable contiguous tumor mass. Until now, efforts to delineate the role of KSHV in the pathogenesis of PELs have been hampered by the lack of appropriate model systems and the concomitant presence of Epstein-Barr virus (EBV) in nearly all cases examined, and in all previously established cell lines. We now report the establishment and characterization of a novel PEL cell line, BC-3, which is KSHV+ by polymerase chain reaction (PCR) but EBV- as assessed by a variety of methods including PCR for EBER, EBNA-2, and EBNA-3C. This cell line was established from a lymphomatous effusion obtained from an HIV- patient, and has immunophenotypic and molecular features consistent with the diagnosis of PEL, including an indeterminate immunophenotype with a B-cell immunogenotype and lack of c-myc proto-oncogene rearrangements. Pulsed-field gel electrophoresis shows an intact KSHV genome of about 170 kb both in the cell line and in the viral isolate, whereas herpesvirus-like capsids are visible by electron microscopy. Consequently, the BC-3 cell line represents an invaluable tool as a source of KSHV, for both the evaluation of the pathogenic potential of this virus and the mechanistic characterization of its role in the development of Kaposi's sarcoma and malignant lymphoma.

Kaposi's sarcoma-associated herpesvirus in non-AIDS related lymphomas occurring in body cavities

DNA sequences belonging to the recently discovered Kaposi's sarcoma-associated herpesvirus (KSHV), now provisionally designated human herpesvirus 8, have been previously identified in an uncommonly occurring subset of AIDS-related lymphomas, referred to as body-cavity-based lymphomas (BCBLs), which present as lymphomatous effusions. Pyothorax-associated lymphomas (PALS) are non-Hodgkin's lymphomas that arise in the pleural cavity after long-standing pleural inflammation resulting from therapeutic artificial pneumothorax or from tuberculosis pleuritis. Although PALs present as solid tumor masses, they are otherwise similar to BCBLs in that they also are B cell lymphomas, usually exhibit immunoblastic morphology, and contain Epstein-Barr virus. We investigated whether KSHV sequences are present in 2 BCBLs in patients without AIDS and 12 in Japanese and 2 French PALs. The 2 BCBLs were positive for KSHV sequences, whereaas all 14 PALs were KSHV negative. This finding strongly suggests that BCBLs and PALs are distinct clinicopathological entities and further strengthens the association between the presence of KSHV and an effusion phenotype. Based on these findings, we propose replacing the term body-cavity-based lymphoma with the term primary effusion lymphoma, which describes these non-Hodgkin's lymphomas more accurately and avoids confusion with other lymphomas that may occur in the body cavities, such as the PALs.

Remission of acromegaly caused by pituitary carcinoma after surgical excision of growth hormone-secreting metastasis detected by 111-indium pentetreotide scan

GH-secreting carcinomas of the pituitary are extremely rare. We describe a 37-yr-old woman with refractory acromegaly 15 yr after transphenoidal surgery and radiotherapy, with no evidence of a recurrent pituitary mass. Scanning with 111-indium pentetreotide revealed an area of intense activity in the left neck. A 3.5 x 2.5-cm mass was excised from the neck after demonstrating an arterio-venous GH gradient of 7:1. GH levels (50 ng/mL) dropped to 0.8 ng/mL 3 h after surgery and remained normal. GH gene expression was demonstrated in the metastasis by Northern and Western blot analyses and by positive immunocytochemistry and immunoelectron microscopy. In vitro cultured cells responded to GHRH and TRH by increasing GH levels (P < 0.01). Medium GH was identical to authentic pituitary GH, as demonstrated by high pressure liquid chromatography. RT-PCR of hypothalamic hormone receptor messenger RNA in the mass revealed somatostatin receptor subtypes 2, 3, and 5 and GHRH, TRH, and dopamine receptor expression. No GH gene amplification, rearrangement, or gsp mutation was found. RB gene deletion and H-ras mutations, previously reported in PRL- and ACTH-secreting carcinomas, were not detected. In conclusion, clinical and molecular features of a GH-secreting pituitary carcinoma are presented. This metastatic lesion synthesized GH and expressed functional hypothalamic hormone receptors.

p53 in lymphomas of mucosal-associated lymphoid tissues

Lymphomas of mucosal-associated lymphoid tissues (MALT) constitute a distinct clinicopathologic entity comprised of centrocyte-like cells with a characteristic morphologic appearance and immunophenotype. The origin of these cells is still undetermined, although evidence suggests that they might derive from marginal zone lymphocytes present in normal lymph nodes and spleens. Recently, marginal zone lymphomas have been shown to have a high rate of p53 mutation. To determine whether p53 mutations were also present in MALT lymphoma, we evaluated specimens from eight patients (six gastric specimens, one parotid, and one from the small bowel) for p53 mutations using polymerase chain reaction and single strand conformational polymorphism analysis. Exon-4 through exon-8 were evaluated, because these are common sites of p53 mutation. In addition, tissues from 15 patients with MALT (including seven studied by single strand conformational polymorphism analysis) were examined for expression of p53 gene protein product by immunohistochemical techniques. All specimens were negative for p53 mutations, suggesting that mechanisms of lymphomagenesis are different for MALT than for splenic marginal zone lymphomas. Despite the absence of p53 point mutations, p53 gene product was localized in tissues from three of 15 patients with MALT. Staining was restricted to nuclei of neoplastic cells and was present in less than 10% of the cells. In summary, low-grade MALT lymphomas differ from marginal zone lymphomas in lacking p53 point mutations, although some patients express low levels of p53 gene product.

mdm-2 oncogene expression in non-Hodgkin's lymphomas

The mdm-2 protein is a 90-kD protein that forms a complex with the p53 protein, enabling cells from some human neoplasms to overcome the growth-suppressing activity of p53. Most non-Hodgkin's lymphomas lack p53 mutations, and the mechanism of inactivation of tumor suppressive function remains obscure. To assess the role of mdm-2 in lymphomagenesis, 22 cases were evaluated for mdm-2 gene amplification or rearrangement in Southern blots. Localization of the mdm-2 protein was performed on cryostat sections and compared with expression of the p53 gene product. No case exhibited mdm-2 gene amplification or rearrangement, but overexpression of nuclear mdm-2 gene protein product was found in three of six diffuse large cell (B-cell immunoblastic) lymphomas (30-70% of the tumor cells stained). The mdm-2 protein was absent from low- and intermediate-grade lymphomas with the exception of a few cells (5% or less) in four cases. The mdm-2-positive cases stained negative for p53. Southern blot analysis showed that samples overexpressing mdm-2 did not have amplification or rearrangement of the gene. In summary, amplification of the mdm-2 gene does not appear to play a prominent role in the pathogenesis of non-Hodgkin's lymphomas, although overexpression of the protein gene product occurs, particularly in high-grade neoplasms.

Failure of liver transplantation to diminish cardiac deposits of amylopectin and leukocyte inclusions in type IV glycogen storage disease

Orthotopic liver transplantation has been used to treat glycogen storage disease type IV. Most long-term surviving patients who have undergone liver transplantation have been free of neuromuscular and cardiac morbidity, and regression of cardiac amylopectin infiltration has been reported after liver transplantation. Leukocyte inclusions in glycogen storage disease type IV have also been reported. We present the case of a child who underwent orthotopic liver transplantation for glycogen storage disease type IV. In contrast to previous reports, at autopsy 2 1/2 years after transplantation, there was massive amylopectin deposits in his heart. Further, peripheral leukocytes never showed loss of amylopectin inclusions after transplantation. Orthotopic liver transplantation for type IV glycogen storage disease may not, in all cases, result in improvement in other affected organs. Consideration of multiorgan transplantation appears warranted.

Alterations of the p27KIP1 gene in non-Hodgkin's lymphomas and adult T-cell leukemia/lymphoma

The protein p27KIP1 belongs to a recently identified family of proteins termed cyclin-dependent kinase inhibitors (CDKIs). These proteins play an important role in regulating cell-cycle progression and loss of their function has been implicated in tumorigenesis. Transforming growth factor beta (TGF-beta) may induce cell growth arrest through p27 activation. TGF-beta often loses its ability to arrest growth of transformed cells; this could potentially occur through a defect in p27. To determine the role of p27 in tumorigenesis, we examined its mutational status in 74 non-Hodgkin's lymphomas (NHLs) (52 of B-cell phenotype, 22 of T-cell phenotype), 5 lymphoma cell lines, and 42 adult T-cell leukemias/lymphomas (ATLs) using polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) and Southern blot analyses. A nonsense mutation (stop codon) that could result in expression of a truncated nonfunctional p27 protein was detected at codon 76 in one case of acute lymphomatous ATL, but not in matched normal tissues. Previously undescribed polymorphisms were also identified at codon 109 in the lymphomas and at codon 55 in the ATLs. Two homozygous deletions of the p27 gene were detected in one case of B-immunoblastic NHL and in one case of acute ATL by Southern blot hybridization. These results indicate that p27 gene alterations are rare events in NHLs and ATLs, but may play an important role in the pathogenesis of some hematologic malignancies.

Deletions of the cyclin-dependent kinase inhibitor genes p16INK4A and p15INK4B in non-Hodgkin's lymphomas

The tumor suppressor genes p16INK4A and p15INK4B map to the 9p21 chromosomal locus and are either homozygously deleted or mutated in a wide range of human cancer cell lines and tumors. Although chromosome 9 abnormalities have been described in non-Hodgkin's lymphomas (NHLs), to date, the mutational status of these genes has not been determined for these malignancies. A total of five cell lines and 75 NHLs were examined for homozygous deletions or point mutations in the coding regions of both the p15 and p16 genes using Southern blot and/or polymerase chain reaction-single-strand conformation polymorphism analyses. Homozygous deletions of either the p16 gene or both the p15 and p16 genes were observed in one diffuse large B-cell lymphoma cell line and two uncultured lymphomas consisting of one large B-cell and one mixed T-cell lymphoma. In contrast, point mutations were not detected in either the cell lines or lymphomas. These results indicate that the rate of alterations in the p15 and p16 genes is low for lymphomas, but loss of p16 and/or p15 may be involved in the development of some lymphomas.

Kaposi's sarcoma-associated herpesvirus-like DNA sequences in AIDS-related body-cavity-based lymphomas

BACKGROUND

DNA fragments that appeared to belong to an unidentified human herpesvirus were recently found in more than 90 percent of Kaposi's sarcoma lesions associated with the acquired immunodeficiency syndrome (AIDS). These fragments were also found in 6 of 39 tissue samples without Kaposi's sarcoma, including 3 malignant lymphomas, from patients with AIDS, but not in samples from patients without AIDS.

METHODS

We examined the DNA of 193 lymphomas from 42 patients with AIDS and 151 patients who did not have AIDS. We searched the DNA for sequences of Kaposi's sarcoma-associated herpesvirus (KSHV) by Southern blot hybridization, the polymerase chain reaction (PCR), or both. The PCR products in the positive samples were sequences and compared with the KSHV sequences in Kaposi's sarcoma tissues from patients with AIDS.

RESULTS

KSHV sequences were identified in eight lymphomas in patients infected with the human immunodeficiency virus. All eight, and only these eight, were body-cavity-based lymphomas--that is, they were characterized by pleural, pericardial, or peritoneal lymphomatous effusions. All eight lymphomas also contained the Epstein-Barr viral genome. KSHV sequences were not found in the other 185 lymphomas. KSHV sequences were 40 to 80 times more abundant in the body-cavity-based lymphomas than in the Kaposi's sarcoma lesions. A high degree of conservation of KSHV sequences in Kaposi's sarcoma and in the eight lymphomas suggests the presence of the same agent in both lesions.

CONCLUSIONS

The recently discovered KSHV DNA sequences occur in an unusual subgroup of AIDS-related B-cell lymphomas, but not in any other lymphoid neoplasm studied thus far. Our finding strongly suggests that a novel herpesvirus has a pathogenic role in AIDS-related body-cavity-based lymphomas.

Multilocular thymic cyst. A novel thymic lesion associated with human immunodeficiency virus infection

Thymic involvement is an important feature of human immunodeficiency virus-related disease in the pediatric population. The most common lesions are thymic involution or atrophy, thymitis (thymic lymphoid hyperplasia), and dysinvolution with loss of Hassall's corpuscles. We report a case of an unusual form of thymic enlargement in a human immunodeficiency virus-infected boy. In addition to lymphoid hyperplasia similar to that associated with human immunodeficiency virus infection in lymph nodes and other sites, the thymus was characterized by multilocular cysts with squamous epithelial lining (multilocular cystic lesion of the thymus).

Changes in tonsils and adenoids in children with posttransplant lymphoproliferative disorder: report of three cases with early involvement of Waldeyer's ring

Posttransplant lymphoproliferative disorder (PTLD) is an infrequent complication of transplantation in children, and this report emphasizes the value of tonsil and adenoid biopsy in the early management of this potentially life threatening condition. In all three cases biopsy specimens of tonsils and adenoids were diagnostic of polymorphic diffuse B-cell hyperplasia (PBCH). Immunophenotyping showed no immunoglobulin (Ig) light chain restriction, although immunoglobulin heavy chain (IgH) gene rearrangement was monoclonal in two cases. Despite an absence of serological evidence for acute Epstein-Barr virus (EBV) infection, EBV was detected in all cases by semiquantitative polymerase chain reaction (PCR) for EBV DNA, by in situ hybridization for EBV mRNA (EBER), and by immunoperoxidase for EBV latent membrane protein (LMP). All three patients were treated with reduced immunosuppression and acyclovir and are well (19, 28, and 28 months' follow-up) with no recurrence. Children without previous EBV exposure may develop PTLD localized to the tonsils/adenoids, and biopsy specimens of these tissues may permit early diagnosis and clinical intervention. Despite monoclonal gene rearrangement in two cases, overall features were not indicative of malignancy. Strong association with EBV is helpful in confirming the diagnosis of PTLD and is consistent with initial presentation in the tonsils/adenoids.

Bcl-2 oncogene protein is preferentially expressed in Reed-Sternberg cells in Hodgkin's disease of the nodular sclerosis subtype

One hundred three cases of nodular sclerosis (NS) and mixed-cellularity Hodgkin's disease were evaluated for expression of bcl-2 oncogene protein, because previous studies have revealed expression of bcl-2 in these subtypes but only rarely in the nodular lymphocyte-predominance subtype. Reed-Sternberg (RS) cells and lacunar variants were positive for bcl-2 in 51 of 86 NS cases and 4 of 17 mixed-cellularity cases. In individual cases of NS, the percentage of RS cells and lacunar variants positive for bcl-2 ranged from minimal (in 5 cases) to 100% positive (mean, 34%). By univariate analysis, expression of the bcl-2 gene product in RS cells was observed in a significantly greater proportion of NS Hodgkin's disease cases than MC cases (P < .009), a finding that may have implications on the pathogenesis of this disorder.

Transactivational and DNA binding abilities of endogenous p53 in p53 mutant cell lines

Cells with divergent mutant alleles of the p53 gene have different biological and biochemical properties in vitro. Increasing evidence indicates that p53 is a transcriptional activator, and recently, high affinity DNA binding sites for p53 have been identified. The purpose of this study was to determine in vivo, the effect that various mutant p53 proteins have on their ability to mediate transactivation and to bind specifically to DNA. Either a p53 responsive or control reporter gene was transfected into 18 human carcinoma cell lines, having various p53 mutations, either with or without a wild-type p53 expression vector. The CAT activity and DNA gel retardation were studied to measure transactivation and DNA binding by these endogenous p53s. As expected, the endogenously produced wild-type p53 binds to DNA binding sequences and can transactivate a reporter construct containing a p53 high affinity DNA binding site. Four of five cell lines with homozygous p53 mutations at codon 273 (273His), contained p53 which had the ability to bind to p53 DNA binding sequences and transactivate. In contrast, all the homozygous, non-codon 273 mutant p53s (156Pro, 175His, 223Leu, 248Gln, 248Trp, 280Lys) present in the other cell lines had no transactivating ability. These findings suggest that the biology of cancers with mutations at codon 273 may be different than those with p53 mutations at other sites. The p53 from WRO, a thyroid carcinoma cell line with p53 mutation at codon 223 (223Leu), was able to bind p53 DNA recognition sequences, but was unable to transactivate. Interestingly, in a vulvar carcinoma cell line (A431) with a p53 mutation at codon 273 (273His), the p53 was unable to transactivate and gave an aberrant band on gel retardation. Both CEM and SK-UT-1, which have compound heterozygous mutations at codons 175/248 (175His/248His), produced p53 which can complex with DNA, as well as transactivate. In contrast, the p53 in cell lines with either homozygous 175His or 248His p53 mutations, were unable either to transactivate or bind to the p53 response element. A cell line (NPA) heterozygous for 266Glu p53 mutation, was able to efficiently transactivate a reporter containing a p53 DNA binding site, therefore showing no evidence of a dominant negative effect of the endogenous p53 mutant allele. In summary, this in vivo study further supports the idea that different p53 mutant alleles have various properties which may affect their function.

Immunohistochemical detection of Epstein-Barr virus-encoded latent membrane protein in Reed-Sternberg cells and variants of Hodgkin's disease

A total of 186 specimens of Hodgkin's disease of various histologic types (127 nodular sclerosis, 39 mixed cellularity, 14 lymphocyte predominance, 3 lymphocyte depleted, and 3 unclassified) were evaluated for the presence of latent membrane protein (LMP) and Epstein-Barr virus nuclear antigen-2, two Epstein-Barr virus encoded gene products that appear to play important roles in cell transformation and oncogenesis. Immunoreactivity for LMP was observed in Reed-Sternberg cells and variants of 27/39 (69%) cases of mixed cellularity type, 18/127 (14%) of nodular sclerosis type, 2/3 cases of lymphocyte depleted type, and 1/3 cases of unclassified type. All cases of lymphocyte predominance Hodgkin's disease were nonreactive for LMP. In cases that were reactive for LMP, staining was restricted to Reed-Sternberg cells and variants. Other cells within the proliferation, e.g., lymphocytes, histiocytes, eosinophils, fibroblasts, etc., were nonreactive. The pattern of immunoreactivity for LMP was characterized by strong diffuse cytoplasmic staining, occasionally with membrane accentuation and/or paranuclear staining. Reactivity for LMP was demonstrated in cryostat sections and was also well preserved in paraffin sections of B5- or formalin-fixed tissues. Five of six specimens of Hodgkin's disease (4 mixed cellularity and 2 nodular sclerosis type) that occurred in HIV-positive patients exhibited immunoreactivity for LMP in Reed-Sternberg cells and variants. Cryostat section studies for Epstein-Barr virus nuclear antigen-2 using monoclonal antibody PE-2 failed to reveal staining for 43 cases (26 nodular sclerosis, 12 mixed cellularity, and 5 lymphocyte predominance) after a 2-h incubation with primary antibody.(ABSTRACT TRUNCATED AT 250 WORDS)

Is immunoreactivity for p53 useful in distinguishing benign from malignant effusions? Localization of p53 gene product in benign mesothelial and adenocarcinoma cells

p53 protein is a "natural tumor suppressor" that plays an important role in controlling cell proliferation. Alterations resulting in overexpression of this gene product have been described in a wide variety of human malignancies. We utilize two commercially prepared monoclonal antibodies to assess the potential role of immunoreactivity for p53 protein in distinguishing benign mesothelial from adenocarcinoma cells in effusion smears. p53 protein was detected in adenocarcinoma cells in 78% of the malignant fluids studied. Benign mesothelial cells in 14% of these fluids and in 73% of the benign fluids also stained for p53. Differences in staining were observed with the Bp-53-12-1 and the 1801 antibodies. Intensity, intracellular distribution, and frequency of immunoreactivity within each cell population are described. Observations are discussed in relation to sensitivity and specificity of the monoclonal antibodies for different configurational forms of p53 protein, configurational modifications of p53 protein during the cell cycle, and diagnostic evaluation of effusion smears for the presence of malignant cells. Immunoreactivity for p53 does not correlate with site of primary tumor. Although overexpression of p53 is more frequent in adenocarcinoma cells than in reactive mesothelial cells, p53 protein overexpression is not necessarily indicative of malignancy.

Localization of p53 protein and human papillomavirus in anogenital squamous lesions: immunohistochemical and in situ hybridization studies in benign, dysplastic, and malignant epithelia

p53 Protein is a 53-kd nuclear phosphoprotein believed to play an important role in controlling proliferation of neoplastic and normal cells. This "natural tumor suppressor" can be rendered ineffective (or oncogenic) by mutations in the p53 gene or by interactions with proteins synthesized by DNA-transforming viruses, including specific subtypes of human papillomavirus (HPV). We describe the localization of p53 protein in association with HPV in paraffin sections of a spectrum of benign, dysplastic, and malignant anogenital squamous epithelia using immunohistochemical and in situ hybridization techniques. p53 Was detected in 81% of the 48 cases studied. Immunoreactivity for p53 was seen in 83% of the benign and low-grade squamous intraepithelial lesions (SILs), in 73% of the high-grade SILs, and in 86% of the infiltrating squamous carcinomas. In high-grade SILs p53 staining was frequently observed in individual nuclei at various levels of the abnormal epithelium and in the basal layer of the adjacent epithelium, while in squamous metaplasia and low-grade SILs immunostaining for p53 was limited to the basal layer of the epithelium. p53 Was detected in a slightly higher percentage of HPV-positive than HPV-negative epithelia as determined by in situ hybridization. No correlation was observed between p53 immunoreactivity and HPV subtypes. p53 Protein and HPV were detected in anal lesions from a small group of human immunodeficiency virus-positive individuals. Antibodies currently available mainly demonstrate mutant forms of p53 protein that are associated with longer half-lives than the wild-type protein, but demonstration of p53 protein overexpression is not necessarily indicative of malignancy.

Mutation and protein expression of p53 in acquired immunodeficiency syndrome-related lymphomas

p53 mutations are found in a variety of neoplasia. B-immunoblastic lymphoma (BIBL) is a rapidly progressive, aggressive lymphoma. As patients with acquired immunodeficiency syndrome (AIDS) live longer, BIBL is becoming an increasing problem. We asked three questions in our study. What is the frequency of p53 mutations in BIBL? Is it more frequent in patients with AIDS? Can immunohistochemical staining of lymph nodes for expression of p53 substitute for mutational analysis of p53 to detect lymphomas with mutated p53? Exons 5, 6, 7, 8 of the p53 gene (hot-spots for mutations) were amplified and examined for mutations by single-strand conformation polymorphism (SSCP) analysis. Altered migration was observed in 7 of 52 BIBL samples. Of these, 4 of 25 were from individuals infected with human immunodeficiency virus (HIV) and 3 of 27 were not infected with HIV. Direct sequencing of amplified material confirmed the presence of mutations in exons 5, 7, 8 of p53. A total of 26 BIBL as well as other lymphoma/leukemia samples, stained strongly by immunohistochemistry with three antibodies directed against human p53. Five of 6 BIBL samples with p53 mutations stained strongly for p53, but 20 lymphoma samples with no detectable p53 mutations also stained strongly for p53. Of note, however, 10 hyperplastic, nonmalignant lymph nodes from individuals either infected or not infected with HIV had negligible staining for p53 protein. In conclusion, p53 mutations occur in about 14% BIBL samples; the frequency of p53 mutations in BIBL in individuals with and without AIDS was similar. Positive p53 immunohistochemistry did not correlate with detectable p53 mutations in the same tissue, but positive immunohistochemical staining for p53 was only found in neoplastic lymph nodes. This latter finding provides a strong warning that p53 immunochemistry with available reagents cannot be used to determine which tumors have mutations of p53.

Immunohistochemical analysis of p53 expression in malignant lymphomas

p53 is a tumor suppressor gene that commonly undergoes mutations in human tumors, including lymphomas. Because p53 mutations are not restricted to a single locus, immunohistochemistry is useful to detect p53 expression and correlate this finding with lymphoma phenotype. Cryostat sections from 125 cases of lymphoma were analyzed for p53 expression using three different monoclonal antibodies (pAb 421, 1801, 240) which react with human cellular p53 and a common conformational epitope on mutant p53. A control antibody (pAb 246) reacts only with wild type p53 of murine origin and was negative in all cases. Tissue from 29 cases of lymphoid hyperplasia, including six from human immunodeficiency virus-positive (HIV+) patients, were negative for p53. p53 was predominantly localized in nuclei of high-grade lymphomas, including 14 of 46 cases of B cell immunoblastic lymphomas and two of five T cell immunoblastic lymphomas. p53 expression was relatively common in lymphomas from HIV+ patients, and unusual in intermediate and low-grade lymphomas of follicular center cell type. Low-grade lymphoma of small lymphocytic type disclosed p53+ large cells (paraimmunoblasts) that may play a role in tumor progression in this lymphoma subtype. p53 was also strongly expressed in the nuclei of Reed Sternberg cells from 19 of 37 cases of Hodgkin's disease, including six cases of mixed cellularity, and 13 cases of nodular sclerosing type. Immunohistochemical staining is a rapid method to identify p53 expression in lymphomas.

The immunohistochemistry of Hodgkin's disease

Immunohistochemistry is a valuable adjunct to the identification of Hodgkin's disease (HD) Reed-Sternberg (RS) cells, and in the differential diagnosis between HD, non-Hodgkin's lymphomas, and nonlymphoid neoplasms containing RS-like cells. The characteristic phenotype of RS cells in different subtypes of HD is described, with an emphasis on routine immunohistochemical stains. Some of the conflicting literature on this subject is reviewed to highlight pitfalls and controversies in the field.

A histiocyte-specific marker in the diagnosis of malignant fibrous histiocytoma. Use of monoclonal antibody KP-1 (CD68)

KP-1 (CD68) is a recently described monoclonal antibody to a cytoplasmic epitope present on tissue histiocytes and macrophages. To determine the specificity and sensitivity of this marker in the evaluation of cases of malignant fibrous histiocytoma (MFH), this reagent and a panel of commercially antibodies were used to stain formalin-fixed paraffin sections from 25 cases of MFH and 25 other tumors, including a variety of soft-tissue sarcomas. Eighteen of 25 cases of MFH stained for KP-1 (72%), whereas all other tumors were negative, including 12 cases of pleomorphic soft-tissue sarcoma other than MFH. The percentage of tumor cells staining for KP-1 varied. In 11 cases KP-1 was only focally present, but staining was of a high intensity and associated with minimal nonspecific or background staining. Pleomorphic histiocytic cells and spindle cells from storiform tumors were strongly decorated with antibodies to KP-1 in most cases, and antigen also was present on tumor giant cells. Although alpha-1-antitrypsin and alpha-1-chymotrypsin stained a higher percentage of cases of MFH (92%), immunoreactivity for these markers also was noted in other tumors. Because of its specificity as a histiocyte marker, KP-1 is a useful component in a panel of antibodies for the characterization of soft-tissue sarcomas and the diagnosis of MFH.

Undifferentiated (embryonal) sarcoma of the liver. A tumor of uncertain histogenesis showing divergent differentiation

Pathologic features of eight cases of undifferentiated (embryonal) sarcoma of the liver (USL) in childhood were studied. Light microscopic examination showed a diffuse growth of spindle cells with occasional polygonal cells and multinucleated giant cells and also revealed focal areas of storiform pattern in four tumors, cambium layer formation in one tumor, and alveolar arrangement in one tumor. Immunohistochemical study showed positive staining of proliferating cells for suggestive histiocytic markers (A1AT in 6/6, A1ACT in 5/6, lysozyme in 4/6, and KP1 in 4/6) and for muscle markers (desmin in 4/6 and HHF35 in 3/6). Ultrastructural examination demonstrated that the individual tumors were composed of a mixture of cells having fibroblastic, histiocytoid, fibrohistiocytoid, myofibroblastic, and undifferentiated (primitive mesenchymal) morphologies. Also identified were cells with definite myoblastic morphology in three tumors: leiomyoblastic in one and rhabdomyoblastic in two. In conclusion, the tumor cells in USL show phenotypical diversity comparable to those of malignant fibrous histiocytoma with or without additional rhabdomyosarcomatous or leiomyosarcomatous differentiation.

Immunohistochemical localization of human immunodeficiency virus (HIV) in central nervous system lymphoproliferative disorders of patients with AIDS

Immunohistochemical localization of human immunodeficiency virus type 1. (HIV-1) in central nervous system lymphoma lesions and uninvolved regions of the brain in seven patients with AIDS revealed evidence of frequent association of HIV-labeled macrophages and multinucleated giant cells with the lesions. Five of seven cases displayed a higher density of labeled cells within and at the periphery of mass lesions and angiocentric infiltrates than in brain parenchyma farther than 1 cm from such lesions. In addition, no label was detected within the neoplastic lymphoid cells in any patient. HIV could not be localized within similarly appearing macrophages associated with destructive lesions (e.g. related to cytomegalovirus encephalitis) or small thrombotic infarcts in brain tissue from the same patients. All lymphomas studied were of a high-grade B-cell type with similar histology in multiple sites. Leptomeningeal spread of the tumor was found in all cases. Facilitation of the development of malignant B-cell clonal proliferation might occur in foci of HIV replication. Alternatively, the development of lymphoma may be due to the generalized immunosuppression; in this case, local activation of macrophages in proximity to the malignant lymphocytes might lead to preferential concentration of disseminated virus by these cells.

Absence of bcl-2 major breakpoint region and JH gene rearrangement in lymphocyte predominance Hodgkin's disease. Results of Southern blot analysis and polymerase chain reaction

Recent evidence suggests that nodular lymphocyte predominance Hodgkin's disease (NLPHD) is a distinct entity that may be related to progressively transformed germinal centers, abnormal B-lymphoid hyperplasia, and low-grade B-cell lymphoma. bcl-2 is a marker for the translocation t(14;18)(q32;q21), which occurs in most follicular-derived B-cell lymphomas. Eleven cases of NLPHD and 19 cases of Hodgkin's disease of nodular sclerosis (NSHD) and mixed cellularity (MCHD) type were analyzed for immunoglobulin JH gene rearrangement. bcl-2 translocation was determined with Southern blot analysis and the polymerase chain reaction using biotin labeled probes to the major breakpoint region and the alkaline phosphatase reaction. All cases of NLPHD were negative for JH gene rearrangement and bcl-2 translocation. Cases of NSHD and MCHD were similarly negative for bcl-2, although three cases exhibited clonal JH gene rearrangements. These results confirm that a clonal B-cell population is not detected in NLPHD. Cases of NLPHD differ from most low-grade follicular B-cell lymphomas in that they lack bcl-2 gene rearrangement and t(14;18) translocation at the major breakpoint region.

Polymerase chain reaction for bcl-2 in diagnostic lymph node biopsies

bcl-2 is a marker for the translocation t(14;18)(q32;q21) indicative of follicular B-cell lymphoma. We studied 115 cases of lymphoproliferative disease with the polymerase chain reaction for bcl-2 oncogene using biotin and radiolabeled probes to the major breakpoint and minor cluster regions. Twenty-three percent of B-cell lymphomas were positive for bcl-2. These included 12 of 20 cases of nodular follicular center cell lymphoma (nine small cleaved cell, one mixed small and large cell, and two large cell types). bcl-2 translocation was detected in only three of 45 cases of diffuse B-cell lymphoma, and cases of AIDS-related malignant lymphoma, monocytoid B-cell lymphoma, and mantle zone lymphoma were all negative. Nonneoplastic lymphoid proliferations were negative for bcl-2 including nine cases of abnormal follicular hyperplasia from patients with acquired immunodeficiency syndrome (AIDS) and AIDS-related complex. Cases of T-cell lymphoma and five cases of Hodgkin's disease were also negative. The polymerase chain reaction for bcl-2 is a rapid, sensitive technique in the evaluation of follicular B-cell proliferations, and the use of biotinylated probes and the alkaline phosphatase reaction eliminates the requirement for radioactive reagents.

Diagnosis of malignant lymphoma in effusions from patients with AIDS by gene rearrangement

Patients infected with human immunodeficiency virus are prone to a wide variety of lymphoproliferative disorders. In these patients the clinical presentation of malignant lymphoma often overlaps with that of benign lymphoid proliferations. Both may include lymphadenopathy, splenomegaly, blood and bone marrow dyscrasias, and lymphocyte-rich effusions. Because benign and malignant lymphocyte-rich effusions, as well as effusions from other malignancies, may contain large cells that resemble immunoblasts or Burkitt's cells, cytomorphologic characteristics alone are unreliable for definitive diagnosis of malignant lymphoma. Usual immunotyping panels using antibodies to B- and T-cell markers frequently fail to demonstrate cell lineage in lymphoma cells of patients with acquired immune deficiency syndrome (AIDS). The authors used gene rearrangement to confirm the diagnosis of malignant lymphoma in effusions from three patients with AIDS when routine cell marker studies failed to demonstrate cell lineage or clonality. Use of biotinylated probes eliminated the need for handling radioactive material and enabled performance of studies in a routine immunohistochemistry laboratory.

Specific phenotyping of T-cell proliferations in formalin-fixed paraffin-embedded tissues. Use of antibodies to the T-cell receptor beta F1

Antibody beta F1 to a common framework determinant of the beta subunit of the T-cell receptor (TCR) was used as a specific phenotypic marker for T-cell differentiation in malignant lymphomas. Sensitivity of immunoperoxidase staining in paraffin sections was enhanced by pronase pretreatment, overnight incubation of primary antibody in Tween 20, and use of streptavidin horseradish peroxidase complexes to amplify the reaction. All 43 cases of B-cell lymphoma were negative for TCR. Reed Sternberg (RS) cells in 3 of 20 cases of Hodgkin's disease exhibited cell membrane staining for TCR (all nodular sclerosis type), further evidence that some RS cells may be T-cell derived. Twenty-nine of 44 cases of T-cell lymphoma expressed TCR (66%). These included 11 of 12 cases of peripheral T-cell lymphoma (PTCL) of small and mixed cell type, 8 of 9 cases of lymphoepithelioid cell (Lennert's) lymphoma, and 2 of 4 cases of T-cell lymphoblastic lymphoma. Loss of immunoreactivity for TCR occurred in lymphomas of large or activated T-cell type, including 7 of 9 cases of T-cell immunoblastic lymphoma and 3 of 4 cases of large cell PTCL. Antibody beta F1 is a specific and relatively sensitive marker of T-cell phenotype in formalin-fixed paraffin sections of malignant lymphomas.

Peripheral/post-thymic T-cell lymphomas: a spectrum of disease. Clinical, pathologic, and immunologic features of 78 cases

The clinical, pathologic, and immunologic features of 78 cases of peripheral/post-thymic T-cell lymphomas are described. These neoplasms were extremely heterogeneous and were classified as small lymphocytic, mixed small and large cell, large cell, lymphoepithelioid cell, angiocentric, and adult T-cell leukemia/lymphoma type. Some cases revealed angioimmunoblastic or Hodgkin's-like features. These neoplasms mainly affected older adults (mean age, 57 years; median age, 60 years). Lymphadenopathy represented the most frequent clinical presentation, although most patients demonstrated both nodal (87%) and extranodal involvement (77%) during the course of disease. Sites of extranodal disease included skin/soft tissue, spleen, lung, liver, bone, gastrointestinal tract, central nervous system, peripheral blood, nasopharynx, and retrovaginal tissue. Splenomegaly at presentation was most frequently observed in lymphoepithelioid cell lymphomas. Angiocentric lymphomas involved lung. A mediastinal presentation was typically observed in young adults and associated with a poor prognosis. Patients with gastrointestinal lymphomas presented with bleeding and/or malabsorption. B symptoms were present in most cases (65%). Hypercalcemia occurred in four patients. Phenotypic studies of T-cell antigens demonstrated the loss of one or more pan-T-cell markers in eight of 47 cases evaluated. Assessment of T-cell subsets revealed a helper/inducer phenotype for nearly all immunoreactive cases. For the overall series, 32 patients died of disease (median survival time, 11.5 mo). There was a statistical difference between the combined groups of small lymphocytic and lymphoepithelioid cell types as compared with mixed and large cell types, with a poorer survival for the latter group. Angiocentric and adult T-cell leukemia/lymphoma were associated with poor survival. This series of T-cell lymphomas further documents the marked heterogeneity of this group of neoplasms as well as the poor prognosis observed for certain histologic types.

Immunopathology of interstitial cystitis

This study describes histologic, ultrastructural, and immunofluorescence microscopy findings of cystoscopically directed biopsies of lesional tissue and uninvolved bladder from 308 patients with chronic interstitial cystitis (IC) and no evidence of infection, collagen vascular, or other systemic disease. The majority of cases exhibited strong urothelial cell staining for immunoglobulin A (IgA), which was focal or diffusely involved all layers of the epithelium. Electron microscopy revealed widening of the interstitium between urothelial cells, which may explain leakage of IgA into the urine in cystitis patients. Staining for fibrinogen and IgA was present both in lesional biopsies and uninvolved bladder tissue, suggesting a response to injury affecting the entire bladder urothelium. A minor patient population with idiopathic IC revealed granular IgM (with or without C3) in vessel walls of the lamina propria, suggesting immune complex disease. Ultrastructural evidence of vascular damage included necrosis of endothelial cells, fibrin deposition, and reduplication of basement membranes. Staining for IgE correlated with presence of mast cells and was present in less than 2% of cases, indicating that these cells do not play a prominent role in the pathogenesis of the disease. In the majority of patients with IC mucosal staining for IgA and fibrinogen was a characteristic pattern representing increased IgA secretion and a reaction pattern to injury of unknown cause. A subgroup of patients had evidence of vascular damage and immune complex disease. This study therefore defines two main reaction patterns in interstitial cystitis, which may have implications on prognosis and therapy of the disorder.

Leu-22: a preferential marker for T-lymphocytes in paraffin sections. Staining profile in T- and B-cell lymphomas, Hodgkin's disease, other lymphoproliferative disorders, myeloproliferative diseases, and various neoplastic processes

Monoclonal antibody Leu-22 represents an effective reagent for detection of neoplastic and nonneoplastic T-cells in paraffin sections of routinely processed tissues (242 specimens evaluated). In nonneoplastic tissues, immunoreactivity was localized mainly to lymphoid cells corresponding to a T-cell distribution. Immunoreactivity in lymphoid neoplasms, however, was preferentially, but not exclusively, limited to T-cell populations. Fifty-four of 60 T-cell neoplasms (90%) of various histologic types were Leu-22 positive. The pattern of immunoreactivity consisted mainly of membrane staining, with focal weak cytoplasmic positivity. Twenty-five of 67 B-cell neoplasms (37%) were also Leu-22 positive, with low-grade lymphomas (well/moderately well-differentiated lymphocytic types) representing most immunoreactive cases. In Hodgkin's disease, although most small lymphoid cells were Leu-22 positive, only rare Reed-Sternberg cells were immunoreactive. In all cases, histiocytes and myeloid cells exhibited variable immunoreactivity. The epitope identified by Leu-22 was detectable in formalin- and B5-fixed tissues but apparently was denatured after fixation in Zenker's-acetic acid solution used for bone marrow biopsies. Evaluation of a wide variety of nonhematopoietic neoplasms (64 total) revealed diffuse cytoplasmic staining in a few cases. However, membrane staining, typically noted for lymphoid cells, was not observed. Leu-22 potentially represents a useful marker for lymphoid cells, preferentially of T-cell origin, with optimal applicability as part of a panel that includes an effective pan-B-cell marker.

AIDS-related lymphadenopathies

Lymphoid proliferations in the acquired immunodeficiency syndrome reflect the profound immunologic imbalances induced by the lymphotropic human immunodeficiency virus, and comprise a range of lymphoproliferative disorders from benign lymphadenopathy to malignant lymphoma. Persistent generalized lymphadenopathy (PGL) is associated with a frequently debilitating complex of clinical symptoms and waxing and waning lymphadenopathy. Biopsies of lymph nodes, bone marrow, and other involved tissues show a spectrum of abnormal lymphoid proliferations, with eventual lymphoid depletion, lymphadenopathic Kaposi's sarcoma, and malignant lymphoma. Although individual features of AIDS-related lymphadenopathy may not be specific, the constellation of histologic, immunologic, and ultrastructural findings is highly characteristic of the disorder and useful as a predictor of clinical course. Malignant lymphomas that develop within this setting of multicloncal B cell expansion and impaired immune surveillance have distinctive clinical, histologic, and molecular biologic parameters.

Hodgkin's disease, lymphocyte predominance type, nodular--further evidence for a B cell derivation. L & H variants of Reed-Sternberg cells express L26, a pan B cell marker

Immunoreactivity for L26, a highly effective pan B cell marker that can be detected in paraffin sections, was evaluated in 72 cases of Hodgkin's disease of various histologic types. In all cases of nodular lymphocyte predominance type of Hodgkin's disease, L & H variants of Reed-Sternberg cells uniformly exhibited strong immunoreactivity for L26. Other variants of Reed-Sternberg cells, eg, lacunar, mononuclear, and diagnostic forms, present in nodular sclerosis, mixed cellularity, and lymphocyte depletion types of Hodgkin's disease, infrequently expressed L26 reactivity. In 55 of 63 cases (87%) of these combined types, less than 5% of Reed-Sternberg cells or variants were L26 positive. In the remaining cases, a larger proportion of these cells expressed L26. Topographic patterns of immunoreactivity for small lymphocytes in these different types of Hodgkin's disease also varied. In nodular lymphocyte predominance type, L26 positive lymphocytes (presumptive B cells) were mainly localized to nodular areas of the proliferation. In other types of Hodgkin's disease, L26 positive cells occurred in small or large aggregates and generally represented a minor proportion of the population of lymphoid cells. These studies further support a B cell derivation for L & H variants of Reed-Sternberg cells and provide additional evidence that nodular lymphocyte predominance type Hodgkin's disease may represent a distinct entity, possibly an unusual low grade B cell lymphoma. These data also suggest that some Reed-Sternberg cells and variants present in other histologic types of Hodgkin's disease may be of B cell derivation, and precludes the use of L26 as a diagnostic discriminant in cases in which the distinction between Hodgkin's disease and non-Hodgkin's lymphoma is unclear.

Cytodiagnosis of malignant melanoma. Immunoperoxidase staining with HMB-45 antibody as an aid to diagnosis

The specificity and sensitivity of HMB-45, an antimelanoma monoclonal antibody, was evaluated in cytologic specimens from extracutaneous melanomas. Melanoma cells in 23 of 25 (92%) cases stained with this antibody. Staining was intense and diffuse in 22 of these melanomas and focal in 1. Amelanotic tumors and tumors with scanty pigment were included. Neither degree of pigmentation, site of primary, cytologic characteristics of tumor, nor source of specimen predicted the immunostaining pattern. Cytopreparations containing benign (6 cases) and malignant (16 cases) cells with which melanoma may be confused constituted the nonmelanoma group. None of the 22 cases in this group stained. Undifferentiated carcinomas, adenocarcinomas, large cell lymphomas, sarcomas, mesothelial hyperplasias, and a benign nerve sheath tumor were included. Effusions, fine-needle aspirates, bronchial material, and imprints were studied. All smears had been fixed and stained by Papanicolaou's method before immunostaining. Excellent cytomorphologic characteristics were preserved, and immunostaining was not affected. HMB-45 antibody is a highly specific and sensitive marker for malignant melanoma in cytologic material.

Immunohistochemical staining for terminal deoxynucleotidyl transferase (TDT). An enhanced method in routinely processed formalin-fixed tissue sections

This report describes an improved technique for sensitive and specific localization of terminal deoxynucleotidyl transferase (TdT) in routinely processed paraffin-embedded, formalin-fixed tissue sections using DNAse pretreatment and the avidin-biotin complex (ABC) technique. This method is useful in identifying lymphoblastic lymphomas (14/15 cases positive), with all other B- and T-cell lymphomas tested negative for the reaction. Used in conjunction with monoclonal antibodies immunoreactive for T- and B-cells in paraffin sections this technique should prove helpful in immunophenotyping malignant lymphomas where fresh tissue is unavailable for study.

Human chorionic gonadotropin expression in lung, breast, and renal carcinomas

Conflicting results have emerged from studies that have examined nontrophoblastic tumor tissue for the presence of human chorionic gonadotropin (hCG) by immunoperoxidase techniques. We evaluated 11 lung carcinomas, ten breast carcinomas, and ten renal cell carcinomas for the presence of immunoreactive hCG by the avidin-biotin-horseradish peroxidase method. The hCG was found in 36% (4/11) of lung tissues, 10% (1/10) of breast tumors, and none of renal tumors. These values are lower than earlier reports for the frequency of detected hCG in the tumor tissue, but they are similar to several more recent studies. The possible reason for these discrepancies are discussed.

DNA content of T-cell lymphomas. A flow-cytometric analysis

Paraffin-embedded archival tissue from 29 cases of malignant non-Hodgkin's lymphoma of T-cell type and 9 control lymph nodes were examined by flow cytometry for DNA aneuploidy and cell-cycle kinetics. DNA aneuploidy was detected in 4 cases (13%) and was not related to histologic grade. Proliferative activity, as measured by proliferative index and S-phase fraction, was significantly increased in lymphomas, compared with controls, and was significantly higher in morphologically high-grade lymphomas, compared with low-grade lymphomas and control lymph nodes (P less than 0.05). Different morphologic types of T-cell lymphoma were also significantly different in their proliferative activity P less than 0.05). Moreover, within the category of peripheral T-cell lymphoma, different proliferative rates occurred in tumors in which small cells predominated, compared with intermediate- and large-cell tumors, suggesting biologic differences within this group.

Ultrastructural localization of Leu M1 in Reed-Sternberg cells and normal myeloid cells

An antigen Leu M1 has been localized to myelomonocytic cells and Reed-Sternberg cells by light microscopic immunocytochemical studies. We used both pre- and post-embedding immunoelectron microscopy to define the ultrastructural distribution of this antigen. Post-embedding techniques heavily labeled the granules of polymorphonuclear leukocytes and the nonspecific granules of eosinophils. At high concentrations there was labeling of the specific granules of the eosinophil. The antibody consistently labeled the perinuclear granules and vesicles of Reed-Sternberg cells. Some Reed-Sternberg cells also exhibited labeling of the endoplasmic reticulum, suggesting that these cells have the capacity to synthesize this antigen. Although plasma membranes were labeled with the post-embedding technique, these structures were most heavily labeled with the pre-embedding method. These results indicate that Leu M1 is synthesized and packaged by Reed-Sternberg cells and represents an integral structural component of these cells.

Epithelial membrane antigen in the cytodiagnosis of effusions and aspirates: immunocytochemical and ultrastructural localization in benign and malignant cells

Immunoreactivity for epithelial membrane antigen (EMA) was evaluated in exfoliated benign and malignant cells using immunoperoxidase and immunogold techniques. In addition, protein A-colloidal gold was used for ultrastructural localization of EMA. Our results suggest that EMA is useful in distinguishing adenocarcinoma cells (strongly positive) from reactive mesothelial cells (negative or weakly positive), lymphoid cells (negative), and a variety of nonepithelial neoplasms (negative) with which they may be confused. Exfoliated cells from two mesotheliomas were also strongly positive for EMA. Ultrastructurally, EMA was distributed in a dense, even, linear pattern along the cell membrane and microvillous surface processes of adenocarcinoma cells. A similar but sparse distribution pattern was observed in reactive mesothelial cells. These observations reflect the increased sensitivity and higher resolution of the immunogold technique.

Detection of estrogen receptors with monoclonal antibodies in routinely processed formalin-fixed paraffin sections of breast carcinoma. Use of DNase pretreatment to enhance sensitivity of the reaction

This study describes an improved immunohistochemical method for the sensitive and specific identification of estrogen receptors (ERs) in paraffin sections from formalin-fixed and routinely processed breast carcinoma tissues, using DNase pretreatment to expose nuclear antigenic sites and commercially available immunoreagents (including monoclonal antibody) in kit form. Results were compared with dextran-coated charcoal cytosolic assay (DCC) and with conventional immunohistochemistry on frozen sections. Sensitivity and specificity for determinations on paraffin sections were 88% and 86%, respectively, and statistical analysis showed very good agreement between DCC and paraffin sections (kappa = 0.805). The DNase technic on paraffin sections allows excellent correlation between histologic characteristics and ER status and reduces DCC sampling error resulting from stromal dilution and tumor variability. This method offers a reliable and reproducible alternative when tissue is not suitable or unavailable for DCC or frozen tissue analysis and can be used for retrospective studies on stored tissue blocks.

Gastroenteropancreatic neuroendocrine tumors. A histochemical and immunohistochemical study of epithelial (keratin proteins, carcinoembryonic antigen) and neuroendocrine (neuron-specific enolase, bombesin and chromogranin) markers in foregut, midgut, and hindgut tumors

Thirty-four gastroenteropancreatic (GEP) neuroendocrine tumors were evaluated for expression of epithelial (keratin, carcinoembryonic antigen [CEA] and neuroendocrine (neuron-specific enolase, chromogranin, bombesin) markers, and results were correlated with histologic patterns and histochemical staining. Tumors of mixed pattern (insular or trabecular with glandular areas) predominated. CEA localization corresponded to staining for mucin, with polarized apical or lumenal staining in glandular areas. Four trabecular midgut carcinoids, however, revealed diffuse cytoplasmic staining for CEA. Staining for keratin proteins was present in 68% of tumors. Bombesin immunoreactivity was demonstrated in 60% of GEP neuroendocrine tumors, indicating that bombesin positive metastatic tumors may not be predominantly of pulmonary origin, as previously suggested. Chromogranin was a sensitive marker for identifying normal gastrointestinal neuroendocrine cells that were not demonstrated by staining for neuron-specific enolase. Chromogranin was present in most neuroendocrine tumors, but was absent from three of five rectal carcinoids in keeping with the distinctive profile of hormonal and silver staining in these tumors. All GEP neuroendocrine neoplasms expressed both neuroendocrine and epithelial markers, supporting their derivation from endodermal epithelium.

Diagnostic immunopathology

The application of immunologic techniques to tissue sections has added a new dimension to the investigation and classification of various processes. Virtually every section of diagnostic pathology has been enhanced by using specific monoclonal antibodies or polyclonal antiserum. Neoplasms formerly diagnosed as poorly differentiated or anaplastic may be precisely identified as to their origin through the use of specific membrane or cytoplasmic markers. Other cellular products, including viruses, hormones, enzymes or highly specific proteins, are also available to study neoplastic and nonneoplastic processes. New and more specific reagents are regularly becoming available for the diagnostic repertoire of pathologists. We present some of the principles of diagnostic immunopathology to show the scope and importance of the techniques.

Endothelial cell markers in vascular neoplasms: an immunohistochemical study comparing factor VIII-related antigen, blood group specific antigens, 6-keto-PGF1 alpha, and Ulex europaeus 1 lectin

Markers for endothelial cells including Ulex europaeus 1 lectin, blood group A, B, and H, and the prostaglandin metabolite 6-keto-PGF1 alpha were evaluated in paraffin secretions from formalin-fixed benign and malignant vascular neoplasms using a variety of immunohistochemical techniques, and results compared with staining for factor VIII-related antigen. Staining for Ulex appeared more sensitive than factor VIII-related antigen in identifying poorly differentiated neoplasms including haemangiosarcomas and spindle cell proliferations in Kaposi's sarcoma. Staining for blood group related antigens correlated with blood group in all cases. Ulex europaeus 1 lectin was the only marker for endothelial cells in lymphangiomas.

Non-Hodgkin's lymphoma, multilobated B-cell type: report of nine cases with immunohistochemical and immunoultrastructural evidence for a follicular center cell derivation

The clinical, pathologic, and immunologic features in nine cases of non-Hodgkin's lymphoma of the multilobated B-cell type are described. Clinical and phenotypic heterogeneity was observed in these B-cell neoplasms. A probable follicular center cell derivation for these cytologically unusual B-cell lymphomas is supported by antecedent histories of follicular center cell neoplasms in three cases; a focal nodular pattern in one case; the demonstration of peanut lectin (PNA) receptors, a marker for follicular center cells, on neoplastic multilobated B cells; and immunoultrastructural studies of nonneoplastic tonsillar cells that identified and characterized rare multilobated cells, immunoreactive for B1, B2, and Ia membrane antigens, a phenotype consistent with follicular center-type cells. Comparison of B- and T-cell multilobated lymphomas revealed that only immunologic studies accurately discriminated between these neoplasms.

Immuno-ultrastructural localization of B-cell-specific monoclonal antibodies B1 and B2

Monoclonal antibodies B1 and B2 are thought to recognize B-lineage restricted antigens, and have been used to define stages of B-cell maturation and characterize B-cell lymphomas. Immunostaining on cryostat sections has revealed a puzzling dendritic or extracellular pattern of staining for B2 within germinal centers and neoplastic follicles. In this study B1 and B2 are localized precisely on hyperplastic and neoplastic lymphoid tissues using immuno-ultrastructural techniques on cryostat sections, cell suspensions, and cell monolayers. B1 and B2 were localized to cell surfaces, including microvillous surface projections, on small and large transformed normal and neoplastic B lymphocytes. B2, in addition to staining in lymphoid cells, was localized to anastomosing cytoplasmic processes of dendritic histiocytes. These findings explain the apparently extracellular localization of B2 in cryostat sections and indicate that patterns of staining for B2 may represent a combination of staining on lymphoid cells and dendritic histiocytes.

Leu-M1 immunoreactivity in nonhematopoietic neoplasms and myeloproliferative disorders. An immunoperoxidase study of paraffin sections

Leu-M1 is a differentiation antigen present on human myelomonocytic cells, which also has been identified in Reed-Sternberg cells and variants of Hodgkin's disease. This study further defines the tissue distribution of Leu-M1, with immunoreactivity observed for neoplastic cells in 14 of 28 formalin-fixed, paraffin-embedded nonhematopoietic neoplasms. With the use of monoclonal antibodies and an indirect immunoperoxidase technic, Leu-M1 was detected in adenocarcinomas of various sites (breast, lung, colon, thyroid, pancreas, and stomach), in squamous cell and transitional cell carcinomas, and in a small-cell anaplastic carcinoma. Evaluation of a wide variety of myeloproliferative disorders indicated that Leu-M1 effectively characterized mature and immature monocytic cells and myeloid cells at late stages of granulopoiesis, but it was not a reliable marker for early myeloid cells including blasts. Leu-M1 monoclonal antibodies are a useful diagnostic reagent, particularly in the assessment of lymphoproliferative disorders, but must be used with extreme caution and full awareness of its staining profile.

Keratoacanthoma and squamous cell carcinoma of the skin: immunohistochemical localization of involucrin and keratin proteins

Fifteen keratoacanthomas and fifteen squamous cell carcinomas of the skin were examined by immunoperoxidase methods for involucrin and both 45- and 63-kilodalton keratins. Keratoacanthomas showed a relatively homogeneous staining pattern for involucrin; all cells except basal cells stained with mild to moderate intensity. Squamous cell carcinomas disclosed a highly irregular involucrin staining pattern with marked variation in staining intensity from cell to cell. Staining patterns for keratin proteins did not appear to distinguish between keratoacanthomas and squamous cell carcinomas. The 45-kilodalton keratin pattern showed diffuse staining within both keratoacanthomas and squamous cell carcinomas, and the 63-kilodalton keratin pattern consisted of focal staining, mostly of dyskeratotic cells. These results suggest that involucrin may serve as a diagnostic aid in differentiating between squamous cell carcinomas and keratoacanthomas. In addition, other lesions in the differential diagnosis of keratoacanthoma and squamous cell carcinoma were also examined for involucrin.

Demonstration of myoglobin and CK-M in myocardium. Comparison of five fixation methods and three immunohistochemical techniques

The results of immunohistochemical staining vary depending on the tissue, fixative, antigen-antibody system, and immunohistochemical staining methods used. The purpose of this study was to evaluate the effect of different methods of fixation, different antigen-antibody systems, and different immunohistochemical methods on immunohistochemical staining of myocardium. Samples of normal fresh canine myocardium from six dogs were fresh frozen and fixed in 10% neutral buffered formalin, Bouin's, Bayley's and Carnoy's fixatives. Immunohistochemical staining for myoglobin and creatine kinase M was performed using the ABC (avidin-biotin complex) and indirect peroxidase-antiperoxidase (PAP) techniques. Tissues fixed in formalin showed the most intense specific staining for both antigens with the least background and nonspecific staining. All other fixation methods and frozen section techniques gave a more variable degree of specific positive staining and substantial background staining and/or nonspecific staining. ABC and PAP techniques gave similar results with both antigen-antibody systems and with each fixation method. Thus, no differences in specificity or sensitivity were observed between ABC and PAP techniques. Differences in staining intensity and pattern were related primarily to differences in fixation methods.