Human lymphocytes bearing T cell receptor gamma/delta are phenotypically diverse and evenly distributed throughout the lymphoid system.

A direct quantitative and phenotypic cytofluorographic analysis of TCR-gamma/delta+ lymphocytes as well as an immunohistologic study of their tissue distribution and microanatomy was made possible by the availability of two mAbs (anti-TCR-delta 1 and anti-C gamma M1) specific for framework determinants on human TCR gamma and delta chains, respectively. TCR-gamma/delta+ lymphocytes, ranging between greater than 0.5 and 16% of CD3+ cells, were found in fetal and postnatal thymus, fetal and adult peripheral lymphoid organs, and adult peripheral blood. While TCR-gamma/delta+ lymphocytes comprised a small subpopulation of T cells (mean, approximately 4%) occasionally greater than 10-16% of CD3+ cells expressed TCR-gamma/delta. Virtually all TCR-gamma/delta+ thymocytes/lymphocytes expressed CD7, CD2, and CD5 but were heterogeneous with respect to their expression of CD1, CD4, CD8, CD28, CD11b, CD16, and Leu-7. Human TCR-gamma/delta+ cells populate both organized lymphoid tissues (thymus, tonsil, lymphnode, and spleen) as well as the gut- and skin-associated lymphoid systems at similar frequencies without obvious tropism for epithelial microenvironments. TCR-gamma/delta+ lymphocytes tend to be located within a given organ wherever TCR-alpha/beta+ lymphocytes are found. This study shows that TCR-gamma/delta+ lymphocytes constitute a small but numerically important, phenotypically diverse T cell population distributed throughout the body. These results support the concept that TCR-gamma/delta+ cells comprise a distinct, functionally heterogeneous, mature T cell sublineage that may substantially broaden the T cell repertoire at all immunologically relevant sites.

Light-chain-restricted germinal centres in reactive lymphadenitis: report of eight cases.

AIMS: Light-chain-restricted germinal centres are generally associated with the existence of a neoplastic lymphoproliferative disorder. The aim was to present a series of cases with persistent lymph node enlargement that featured some germinal centres showing light chain immunoglobulin restriction. METHODS AND RESULTS: A series of six reactive lymphadenitis and two Castleman's disease cases was analysed by immunohistochemistry, IgH-polymerase chain reaction (PCR) and microdissected PCR. In all cases some germinal centres contained a population of plasma cells and plasmacytoid germinal centre cells showing light chain immunoglobulin restriction. In three cases the monotypic cells also showed distinct Bcl-2 expression. Two of the cases showed a predominant IgH rearrangement on a florid polyclonal background and one had an IgH monoclonal rearrangement, as revealed by PCR. Microdissected germinal centre PCR revealed a dominant repeated band in one of three cases and in another case a non-repeated clonal peak was observed. One of the patients developed a follicular lymphoma, which became evident from a subsequent biopsy. CONCLUSIONS: These findings may be a manifestation of an underlying disorder in the regulation of the immune response, or an exaggeration of the germinal centre oligoclonal nature. This should be taken into account in the differential diagnosis of follicular hyperplasia.

Discordance between surface and cytoplasmic expression of the Leu-4 (T3) antigen in thymocytes and in blast cells from childhood T lymphoblastic malignancies.

We have examined the expression of the Leu-4 (T3) antigen on the cell surface and in the cytoplasm of blast cells from 23 patients with T cell acute lymphoblastic leukemia and T cell lymphoblastic lymphoma. In the majority of cases (17), the Leu-4 antigen was absent from the cell surface; however, in 16 of these 17 cases, blast cells demonstrated cytoplasmic expression of Leu-4. This discordance between surface and cytoplasmic expression of Leu-4 was also found in thymocytes and appeared to be restricted to Leu-4, in that tests of other T cell antigens rarely revealed discordance between surface and cytoplasmic expression. To study further the cytoplasmic determinant identified by anti-Leu-4 in malignant T lymphoblasts, immunoprecipitation studies were performed that utilized biosynthetic labeling of established T cell lines derived from T lymphoblastic malignancies. By one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis, identical Leu-4 polypeptide families were immunoprecipitated from surface Leu-4+ and surface Leu-4-/cytoplasmic Leu-4+ cell lines. Because T lymphoblastic malignancies represent proliferations of immature T cells, and because the cases studied demonstrated surface phenotypes corresponding to all of the proposed stages of T cell ontogeny, it appears that cytoplasmic expression of Leu-4 occurs early in T cell development. The reason for the failure of these immature T cells to transport the Leu-4 molecule to their surface remains to be elucidated.

Lymphomas presenting as histologically unclassified neoplasms: characteristics and response to treatment.

Malignant lymphoma is frequently diagnosed when immunohistochemical techniques are applied to otherwise unclassified neoplasms. In this analysis of 35 patients with a histologically unclassified neoplasm that expressed leukocyte-common antigen(s) (LCA), actuarial survival was 63%, and 45% of patients were free from disease progression at 30 months following treatment as for lymphoma. The clinical features at diagnosis and the results of combination chemotherapy were found to be similar to a group of patients with a diagnosis of diffuse large-cell lymphoma (DLCL) concurrently treated at this institution. This study further emphasizes the importance of improved diagnostic techniques in the management of histologically unclassified tumors.

Similar outcome of treatment of B-cell and T-cell diffuse large-cell lymphomas: the Stanford experience.

Although previous studies have suggested a relatively poor prognosis for some patients with peripheral T-cell lymphoma, the clinical significance of immunologic phenotype in diffuse large-cell lymphoma (DLCL) remains controversial. One hundred one patients with a uniform morphologic diagnosis of DLCL treated at Stanford between 1975 and 1986 with cyclophosphamide, Adriamycin (doxorubicin; Adria Laboratories, Columbus, OH), vincristine, and prednisone (CHOP), methotrexate, bleomycin, Adriamycin, cyclophosphamide, vincristine, and dexamethasone ([M]BACOD), or methotrexate, Adriamycin, cyclophosphamide, vincristine, prednisone, and bleomycin (MACOP-B) chemotherapy were studied with regard to immunologic phenotype. Immunologic analysis, performed on frozen or paraffin-embedded tissue, identified 77 cases of B-cell origin, 21 cases of T-cell origin, and three cases that lacked B-cell or T-cell markers. Analysis of complete remission (CR) rates (84% v 95%), 5-year actuarial freedom from disease progression (38% v 53%), and 5-year actuarial overall survival (52% v 79%) showed no statistically significant differences in prognosis between B- and T-cell patients, respectively. The 5-year actuarial survival of patients with stage IV T-cell DLCL (56%) also did not differ in a statistically significant way from stage IV B-cell patients (36%). We conclude that treatment selection for DLCL should not be based on immunologic phenotype alone.

Mediastinal nonlymphoblastic lymphomas in children: a clinicopathologic study.

The records of 25 pediatric patients with mediastinal nonlymphoblastic lymphoma (NLBL) were reviewed. These patients comprise approximately 5% of all patients with non-Hodgkin's lymphoma (NHL) in the pediatric age group. There were 15 females and ten males. The median age was 13.5 years (range, 2 to 19). Most patients presented with symptoms attributable to a large mediastinal mass, and superior vena cava syndrome was a common feature. Disease was localized to the supradiaphragmatic area in 17 patients (71%) at diagnosis. Pathologic review revealed 22 of these lymphomas to be diffuse histiocytic type in the Rappaport classification, and 20 were large-cell immunoblastic type in the Working Formulation. Treatment regimens were not uniform, but included multiagent chemotherapy in 23 patients and radiation to the mediastinum in 20 patients. Twenty-three patients (92%) attained a complete remission (CR). Of these, 17 (74%) remain disease-free 13 to 65 months from diagnosis (median, 43 months). No CNS relapses have been observed. Mediastinal NLBL in the pediatric age group has distinctive clinicopathologic features that warrant special consideration in the design of treatment protocols.

Numbers of host "helper" T cells and proliferating cells predict survival in diffuse small-cell lymphomas.

Diffuse small-cell lymphomas of B-lineage comprise a group of immunophenotypically related lymphoid malignancies that display variable clinical aggressiveness. We compared a variety of clinical, pathologic, and immunologic characteristics of 64 B-lineage diffuse small-cell lymphomas to patient survival in an effort to define prognostically relevant subtypes of these neoplasms. Neither clinical parameters nor histological subclassification correlated with patient outcome. In contrast, three immunologic features of these lymphomas showed a statistically significant relationship with actuarial survival. Neoplasms that manifested greater than or equal to 25% Ki-67+ cells (proliferation-associated antigen), less than 25% Leu 4+ cells (pan-T antigen), or less than 15% Leu 3+ cells (helper/inducer T-subset antigen) were associated with significantly decreased patient survival as compared to neoplasms with the reverse phenotype (P = .02, P = .003, P = .0005, respectively). Leu 3 findings were of particular importance in initial biopsies (P = .0007), while the Ki-67 findings were significant regardless of time of biopsy (P = .01 for biopsies at diagnosis and P = .004 for other biopsies). These data indicate that immunologic analysis can demonstrate subsets of diffuse small-cell lymphoma with different biologic potential, and suggest that such analysis be included in the routine work-up of patients with this type of neoplasm.

Mdr1 gene expression in childhood acute lymphoblastic leukemias and lymphomas: a critical evaluation by four techniques.

Expression of the multidrug resistance gene mdr1 is reported to be an important determinant of responsiveness to therapy and survival in some cancers. Many different methods have been used to evaluate mdr1 expression in these studies. This paper compares four methods for determination of mdr1 expression. We studied the mdr1 gene expression in 36 freshly established cell lines from 28 children with acute lymphoblastic leukemia (16 T-ALL, six BCP-ALL, two B-ALL (L3), two biphenotypic leukemias, two Burkitt's lymphomas). Leukemic specimens were obtained at the time of diagnosis in 16 cases, and after chemotherapy in 20 cases. In all the samples, mdr1 mRNA was measured by slot blotting and reverse transcriptase polymerase chain reaction (rt-PCR), and the presence of the mdr1 product, P-glycoprotein, was detected by immunohistochemistry with the MRK-16 monoclonal antibody. In situ mdr1 RNA hybridization was performed in 30 cases. Complete agreement was noted between all the techniques in 14 cases (39%). Results differed on a single test result in another 39% of the cases. These 78% of cases were considered assessable, and the consensus result was presumed to be correct. By this consensus criterion, immunohistochemistry yields both false negative (11%), and false positive (11%) results. RNA slot blotting has a high (21%) false positive rate. In situ mRNA hybridization and rt-PCR have the highest concordance, 80%. The 28 patients from whom these cell lines were derived appear to represent a very poor prognosis group, since there are only two patients (with Burkitt's lymphoma) who are long-term survivors. Nonetheless, a complete clinical response to therapy was correlated with absence of mdr1 expression in assessable cases (p = 0.04). These four methods of determining mdr1 expression often yield discordant results. Therefore, the use of at least two methods for evaluating mdr1 expression is advisable. Rt-PCR is recommended because of its relative simplicity and specificity. This should be supplemented by a technique (immunohistochemistry or flow cytometry) able to detect heterogeneity of P-glycoprotein expression among cells.

Genetic instability is associated with histological transformation of follicle center lymphoma.

Follicle center lymphoma (FCL) is an indolent B cell non-Hodgkin's lymphoma (NHL) characterized genetically by the t(14;18) translocation. Histological transformation and clinical progression of FCLs are frequently associated with secondary genetic alterations at both nucleic acid and chromosomal levels. To determine the type and pattern of genomic instability occurring in histological transformation of FCLs and the role of DNA mismatch repair defects in this procedure, we have performed microsatellite analysis, comparative genomic hybridization (CGH) and mutational analysis of hMLH1 and hMSH2 genes on serial biopsy specimens from patients with FCL transformed to diffuse large cell lymphoma (DLCL). Paired biopsy samples of eight patients were analyzed for microsatellite instability and structural alterations for hMLH1 and hMSH2 genes, and tumor samples of five patients were subjected to CGH analysis. A high level of microsatellite instability was associated with histological transformation of two cases of FCL, but no mutations of the hMLH1 and hMSH2 genes were detected in any of the lymphoma samples. In the five cases subjected to CGH analysis, the histological transformation of FCLs was associated with genomic imbalances at 21 chromosomal regions. The genomic abnormalities found were rather heterogeneous and none of the genetic changes were overrepresented in the transformed DLCLs. These data suggest that histological transformation of FCLs to DLCL is frequently associated with genome wide instability at both nucleic acid and chromosomal levels, although mutations of the hMSH1 and hMLH2 genes are not involved in this process.

Expression of T-cell receptor antigens in mycosis fungoides and inflammatory skin lesions.

Using immunohistologic methods, we studied the expression of the T-cell receptor (TCR)-associated antigens CD3, TCR-beta, and TCR-delta by cutaneous T cells in mycosis fungoides (MF) (36 patients) and a variety of inflammatory diseases (16 patients). Most T cells in the inflammatory diseases and patch/plaque mycosis fungoides expressed the immunophenotype characteristic of the vast majority of mature peripheral T cells: CD3+ TCR-beta+ TCR-delta-. In contrast, abnormal CD3/TCR-beta antigen expression was seen in 3 of 6 cases (50%) of tumor stage mycosis fungoides. Furthermore, we were able to document its evolution from the normal pattern present in earlier patch/plaque lesions of the two cases in which serial biopsies were available for study. Divergence of epidermal versus dermal CD3/TCR-beta antigen expression was seen in 2 of 34 (6%) of biopsies of patch/plaque mycosis fungoides but not in inflammatory controls. The TCR-delta+ cells were generally rare regardless of diagnosis. We conclude that inflammatory skin diseases and most patch/plaque mycosis fungoides are typically composed of T lymphocytes that resemble mature peripheral T cells in regard to their expression of TCR-associated antigens. In contrast, aberrant patterns of TCR-associated antigen expression can be seen in tumor stage MF, and, more rarely in patch/plaque MF.

Expression of Leu-8 antigen, a majority T-cell marker, is uncommon in mycosis fungoides.

Predominance of mature helper T cells with the Leu-1+, 2-, 3+, 4+, 5+ phenotype was confirmed in 22 biopsy specimens of mycosis fungoides from 15 patients. Dissection of the T helper/inducer cells into phenotypically distinct subsets was performed with the use of a new monoclonal antibody, anti-Leu-8. One might predict a predominance of Leu-8+ in mycosis fungoides, as the known ratio of Leu-8+/Leu-8- cells is approximately 70/30 in the peripheral blood. Unexpectedly, a deficiency of Leu-8 was demonstrated in 18 of the 22 specimens from 13 of 15 patients. This finding could not be attributed to an artifact of the staining method or to therapy, and was present in early- as well as late-stage disease. Whether neoplastic cells in mycosis fungoides derive from Leu-8-subset of T cells at risk for malignant transformation, or whether there is antigen loss with malignant transformation remains to be determined. Implications of our finding with regard to etiopathogenesis of mycosis fungoides are discussed.

Transformation of mycosis fungoides: T-cell receptor beta gene analysis demonstrates a common clonal origin for plaque-type mycosis fungoides and CD30+ large-cell lymphoma.

It is well recognized that patients with classical mycosis fungoides (MF) may develop a large-cell lymphoma (LCL), a phenomenon known as "transformation." An unresolved issue regarding the transformation of MF is whether MF and LCL represent two separate lymphomas or whether they are derived from the same T-cell clone. We report the clinicopathologic, immunophenotypic, and immunogenotypic analysis of MF and LCL in a white male. He developed a rash at age 51 that was diagnosed at age 56 as clinical stage IA patch/plaque MF. After topical nitrogen mustard and total skin electron beam therapy for progressive generalized CD3+CD4+ patch/plaque lesions, he developed nodules of Ki-1+ (CD30+) T-LCL at age 72. Southern blot analysis of DNA digested with Bg/II or BamHI and probed with a T-cell receptor (TCR)-beta gene J beta 1/J beta 2 probe showed a single, identical rearranged band in both the MF and LCL skin lesions that had been obtained 4 years apart. V beta gene family--specific gene amplification assays demonstrated dominant V beta 6 PCR products in both types of lesions. These PCR products and lesional cDNA exhibited a monoclonal pattern when amplified with consensus TCR-beta gene VDJ joint primers and electrophoresed under conditions that allowed the resolution of small differences in size. Furthermore, sequence analysis of the V beta 6 PCR products amplified from both the MF and LCL lesions showed an identical nucleotide sequence involving V beta 6.4, D beta 1.1, J beta 1.2, and C beta 1. These findings indicate that both the MF and the LCL in this patient arose from the same T-cell clone and that these diseases developed at a stage in the clone's differentiation subsequent to rearrangement of the TCR-beta gene.

Vascular transformation of sinuses in lymph nodes. A study of its morphological spectrum and distinction from Kaposi's sarcoma.

Vascular transformation of lymph node sinuses (VTS) is characterized by conversion of nodal sinuses into capillary-like channels, often accompanied by fibrosis. A detailed study of this entity, based on 76 cases, showed that the morphologic spectrum was much broader than that originally described. The vasoproliferative process caused variable expansion of the subcapsular, intermediate, and medullary sinuses of the lymph nodes and involved single or multiple lymph nodes in a diffuse or segmental fashion. The proliferated vessels formed anastomosing narrow clefts, rounded spaces of different sizes, plexiform channels, or solid spindled to plump cellular foci and often were associated with variable degrees of sclerosis. The vascular spaces were empty, filled with lymph-like fluid, congested with blood, or occasionally thrombosed; extravasation of red cells was common. Several patterns were commonly observed in an individual case. Less common features included perivascular fibrin deposition and the presence of eosinophilic globules. Vascular thrombosis was identified only rarely in extranodal vessels available for histologic assessment. The more cellular forms of this vascular transformation may be mistaken for Kaposi's sarcoma, but can be distinguished from it by the pure sinusoidal distribution, a lack of well-formed spindle cell fascicles, the associated fibrosis, the maturation of the spindle cells into well-formed vascular channels toward the capsular aspect, and the failure of this process to involve the capsule itself, which is frequently affected by Kaposi's sarcoma.

Inflammatory pseudotumor of lymph nodes. Additional observations and evidence for an inflammatory etiology.

Inflammatory pseudotumor of lymph nodes (IPT), a recently described benign cause of lymphadenopathy, was studied in 14 patients using paraffin-section immunohistochemistry. All biopsies showed a proliferation of spindle cells (small blood vessels, histiocytes, and "activated" fibroblasts resembling myofibroblasts) containing a mixture of inflammatory cells without atypia and involving the connective tissue framework (hilum and sinuses) of the lymph node. Ten patients had additional histologic features of IPT originally described (extranodal extension, obliterative vasculitis, and endothelial infiltration), and nine of these had associated fever of unknown origin, which in some was relieved by biopsy alone. Additional features observed focally in some cases but not previously described included lymph node parenchymal infarction, fibrinoid vascular necrosis, karyorrhexis, and involvement of only part of the lymph node. Immunostaining showed the lymphoid infiltrate to be predominantly of T-lineage (except for plasma cells), only a minority of which marked as T-helper cells. Numerous mononuclear cells resembling histiocytes were identified, some of which had a spindled shape but reacted with an antibody (KP1) of myelomonocytic specificity. Large fibroblastic cells expressed alpha-muscle actin but not desmin, similar to myofibroblasts in granulation tissue. The morphologic and immunohistologic features were similar to those in inflammatory pseudotumors of spleens and livers also studied, but the lack of simultaneous lymph node involvement argued against a common etiology. The findings suggest that the mass lesion of IPT is produced in response to localized lymph node inflammation or injury and further exclude hematolymphoid or mesenchymal neoplasia as a cause.

Malignant lymphoma presenting as pseudoepitheliomatous hyperplasia. A report of two cases.

The authors report two patients with cutaneous and submucosal non-Hodgkin's lymphoma of probable T-cell phenotype that presented as florid pseudoepitheliomatous hyperplasia. The first patient presented with lesions of the nasopharynx and nose that were originally misdiagnosed as invasive squamous cell carcinoma, causing a delay in appropriate treatment. In the second patient, skin lesions of the thigh and arm closely mimicked squamous cell carcinoma. To prevent misdiagnosis of these lesions, pathologists should adhere to strict morphologic criteria for the diagnosis of squamous cell carcinoma and be aware that malignant lymphoma may be associated with overlying pseudoepitheliomatous hyperplasia. The pathogenesis of pseudoepitheliomatous hyperplasia arising in association with neoplasms is still not clear, but it may be related to the production of cellular growth factors by the inciting tumor.

Non-Hodgkin's lymphomas of the lung. A study of 19 cases emphasizing the utility of frozen section immunologic studies in differential diagnosis.

Nineteen cases of possible non-Hodgkin's lymphoma of the lung were studied by conventional morphologic methods and by immunohistochemical methods employing monoclonal antibodies applied to frozen tissue sections. In five of the 19 cases, the original histologic diagnoses were revised after review of the immunologic findings. Problem areas clarified by immunodiagnosis included the differential diagnoses of pseudolymphoma versus small lymphocytic lymphoma (two cases), Hodgkin's disease versus non-Hodgkin's lymphoma (two cases) and non-Hodgkin's lymphoma versus lymphomatoid granulomatosis (one case). Of the seven lymphomas presenting exclusively in the lung without a prior history of lymphoma, three were small lymphocytic, one was diffuse mixed small cleaved and large cell, and three were diffuse large-cell lymphomas. Four of these lymphomas typed as B-cell, two typed as T-cell, and one was of undefined phenotype.

Coexistence of nodular lymphocyte predominance Hodgkin's disease and Hodgkin's disease of the usual type.

Recent literature suggests that usual Hodgkin's disease (nodular sclerosing and mixed cellularity types or UHD) and nodular lymphocyte predominance Hodgkin's disease (NLPHD) may be distinct clinical and pathologic entities. Thus, coexistence of NLPHD and UHD in the same patient is expected to be rare. We undertook a review of cases accessioned as NLPHD and UHD in the Laboratory of Surgical Pathology at Stanford University Hospital between January 1980 and May 1992 and found five patients with UHD that predated, followed, or coexisted with lesions histologically typical of NLPHD. All of the patients were male with ages ranging from 10 to 30 years at presentation (median, 22 years; mean, 22.2 years). The sites initially involved by disease were primarily peripheral lymph nodes in the region of the head and neck: cervical (three), supraclavicular (one), submandibular (one). One patient presented with mixed-cellularity Hodgkin's disease (MCHD), two with nodular sclerosis Hodgkin's disease including the cellular phase, one with NLPHD, and the remaining patient presented with a composite malignancy comprising MCHD and NLPHD. Development of the second lymphoma was associated with a somewhat more variable distribution of nodal involvement. The morphologic features in each biopsy specimen resembled either typical NLPHD or UHD, except for one case in which cells with features of both Reed-Sternberg cells and lymphocytic and histiocytes cells were identified. However, the immunophenotypic profiles obtained with a panel of monoclonal antibodies remained distinct for all cases studied. None of the cases showed reactivity with antibodies against the Epstein-Barr-virus latent membrane protein. Thus, NLPHD and UHD maintain a distinct phenotype, even when occurring in the same patient. A second conclusion is that the utility of Leu-7 (CD57) reactivity in distinguishing NLPHD applies to problematic as well as classic cases. Finally, Epstein-Barr virus is not implicated in NLPHD cases associated with UHD.

The cells of giant cell tumor of tendon sheath resemble osteoclasts.

To determine whether the mononuclear cells (MC) and multinucleated giant cells (GC) of giant cell tumor of tendon sheath (GCTTS) exhibit evidence of monocyte/macrophage lineage, we studied their antigenic features (seven cases, paraffin sections; two cases, frozen sections) and enzymatic features in situ (four cases, plastic sections). Both MC and GC expressed a monocyte/macrophage phenotype: HLA-A,B,C+, HLA-DR+, T200+ (leukocyte common antigen), Leu-M3+ and Leu-3+. MC and GC also expressed similar enzymatic phenotypes which resembled that of osteoclasts. Both were rich in acid phosphatase and contained smaller, variable amounts of ATPase, beta-glucuronidase, alpha-naphthyl acetate esterase, and 5'-nucleotidase. Both lacked alkaline phosphatase. Reactive osteoclasts in plastic and paraffin sections were also T200+, a finding strongly supporting their bone marrow derivation and leukocytic differentiation. In plastic sections, osteoclasts were additionally reactive with macrophage antigen EBM11. In aggregate, these data suggest that GCTTS is a true histiocytic lesion of monocyte/macrophage lineage composed of phenotypically similar MC and GC that most closely resemble osteoclasts. We found no evidence that GCTTS cells resemble osteoblasts, fibroblasts, or synovial sarcoma cells. Furthermore, expression of the Ki-67 nuclear antigen by 1-2% of MC but not by GC suggests that the proliferating cells in GCTTS are restricted to its MC component.

The diagnostic utility of the keratin profiles of hepatocellular carcinoma and cholangiocarcinoma.

A total of 32 hepatocellular carcinomas (HCC), 10 cholangiocarcinomas (CC), one combined HCC-CC, and 10 adenocarcinomas metastatic to the liver were studied immunohistochemically using AE1 and Cam 5.2, monoclonal antikeratin antibodies with different specificities. AE1 recognizes keratins with molecular weights of 56.5, 50/50', 48, and 40 kd (keratin nos. 10, 14, 15, 16, and 19, according to Moll's catalog), and labels many epithelia, including bile duct epithelium, but not hepatocytes. Both biliary epithelium and hepatocytes are stained by Cam 5.2, which reacts with keratins of molecular weights 50, 43, and 39 kd (corresponding to keratin nos. 8, 18, and 19). Tissues were formalin fixed, paraffin embedded, and a three-stage immunoperoxidase technique was employed. Of 32 pure HCCs, 29 were unreactive with AE1 yet were positive with Cam 5.2. The intensity and extent of immunostaining with Cam 5.2 did not correlate with tumor grade. In contrast to the HCCs, all 10 CCs and the 10 hepatic metastases were strongly positive with both AE1 and Cam 5.2. The combined HCC-CC was also labeled by both antibodies. We conclude that most HCCs express an immunohistochemical keratin profile identical to that of nonneoplastic hepatocytes, which differs from the keratin patterns of bile ducts, CCs, and metastatic adenocarcinomas from a variety of primary sites. These differences in immunoreactivity with antikeratin antibodies may prove useful in diagnostic surgical pathology.

The "syncytial variant" of nodular sclerosing Hodgkin's disease.

The histologic and immunologic features of an unusual morphologic expression of nodular sclerosing Hodgkin's disease, which ahs been termed the "syncytial variant," are described. In biopsy material from 18 cases, numerous Reed-Sternberg cell variants were observed in sheets and cohesive clusters, and at least focal evidence of nodular sclerosis was present in each case. The granulocyte antibody anti-Leu M1 reacted with antigenic determinants in Reed-Sternberg cells and atypical variants thereof in 13 of the 18 cases; the lack of staining with antibodies reactive with the leukocyte common (T200) antigen (PD7/26), keratin (AE1), and S100 protein (polyclonal anti-S100) was helpful in excluding non-Hodgkin's lymphoma, carcinoma, and melanoma, respectively. This unusual form of nodular sclerosing Hodgkin's disease is important to recognize, since it may simulate metastatic neoplasms, thymoma, and non-Hodgkin's lymphoma.