A low frequency of pancreatic islet insulin-expressing cells derived from cord blood stem cell allografts in humans.

AIMS/HYPOTHESIS: We sought to establish if stem cells contained in cord blood cell allografts have the capacity to differentiate into insulin-expressing beta cells in humans. METHODS: We studied pancreases obtained at autopsy from individuals (n = 11) who had prior opposite-sex cord blood transplants to reconstitute haematopoiesis. Pancreatic tissue sections were stained first by XY-fluorescence in situ hybridisation and then insulin immunohistochemistry. Pancreases obtained at autopsy from participants without cord blood cell infusions served as controls (n = 11). RESULTS: In the men with prior transplant of female cord blood, there were 3.4 ± 0.3% XX-positive insulin-expressing islet cells compared with 0.32 ± 0.05% (p < 0.01) in male controls. In women with prior transplant of male cord blood cells we detected 1.03 ± 0.20% XY insulin-expressing islet cells compared with 0.03 ± 0.03 in female controls (p < 0. 001). CONCLUSIONS/INTERPRETATION: Cord blood stem cells have the capacity to differentiate into insulin-expressing cells in non-diabetic humans. It remains to be established whether these cells have the properties of beta cells.

Clusterin promotes the aggregation and adhesion of renal porcine epithelial cells.

The function of clusterin, a heterodimeric glycoprotein markedly induced in renal and other organ injuries, is unclear. Since renal injury is accompanied by alterations in cell attachment, it is possible that clusterin functions to promote cell-cell and cell-substratum interactions. In this study, a single cell suspension of renal epithelial (LLC-PK1) cells was treated with purified human clusterin, resulting in time- and dose-dependent cell aggregation. Electron microscopy of the cell aggregates demonstrated cell junction and lumen formation. To determine the effect of clusterin on cell adhesion, tissue culture plates were coated with clusterin, fibronectin, PBS, or albumin. Clusterin and fibronectin promoted cell adhesion to the same extent. The adhesion to clusterin was dose dependent and specific, as a monoclonal antibody against clusterin inhibited cell adhesion to clusterin but not fibronectin. Perterbations of the cytoskeleton may underlie the alterations in cell attachment which occur in renal injury. Induction of clusterin mRNA was seen after disruption of both microtubules and microfilaments and after inhibition of cell-substratum interactions. In conclusion, clusterin is a potent renal epithelial cell aggregation and adhesion molecule. We speculate that clusterin functions to promote cell-cell and cell-substratum interactions which are perturbed in the setting of renal injury, thereby preserving the integrity of the renal epithelial barrier.

Association of immunohistochemical staining for p53 with metastatic progression and poor survival in patients with renal cell carcinoma.

BACKGROUND: Mutations of the p53 gene have been found in many types of human tumors. In some tumors, p53 gene mutations are associated with advanced disease and poor prognosis. There is wide variation in the reported incidence of p53 mutation in renal cell carcinoma, and its prognostic significance for this tumor is unknown. PURPOSE: This retrospective immunohistochemical study was designed to examine associations between p53 immunostaining and histologic type, tumor grade, clinical behavior, and survival. METHODS: Paraffin-embedded nephrectomy specimens collected from 1978 through 1986 from 175 patients were immunostained for p53 using the D07 monoclonal antibody. Positive staining for p53 has been linked to the accumulation of mutant p53 protein. Thirteen specimens of concurrent metastatic lesions were available from 11 primary cases. Clinical follow-up information was available on 164 patients. RESULTS: Immunostaining for p53 suggested the presence of p53 mutation in 49 (28%) of 175 renal tumors studied. Staining was associated with high tumor grade and stage but not with cell type or histologic pattern. Eleven (85%) of 13 metastatic lesions stained positively for p53, versus only four (36%) of the 11 paired primary tumors. Immunostaining for p53 was strongly associated with poor survival among patients without distant metastases at presentation. In this group, 10-year disease-specific survival was 78% for patients with nonstaining tumors versus 48% for those with p53-positive tumors (P < or = .003). There was an 87% 10-year disease-specific survival rate for patients with nonstaining Robson stage 1 tumors versus a 62% 10-year survival rate for patients with p53-positive Robson stage 1 tumors (P < .01). Multivariate analysis showed p53 immunoreactivity to be an independent predictor of survival for patients with nonmetastatic renal cell carcinoma, whereas tumor grade was not. CONCLUSIONS: Positive p53 immunostaining in renal cell carcinoma is associated with metastatic disease and poor survival in patients with early-stage disease. IMPLICATIONS: In renal cell carcinoma, mutations of the p53 gene may allow or contribute to the acquisition of metastatic potential.

Progression and enhancement of metastatic potential after exposure of tumor cells to chemotherapeutic agents.

Data presented in this report indicate short-term in vitro treatment of nonmetastatic MCF-7 breast carcinoma cells with the chemotherapeutic agents-, Adriamycin and/or 5-fluoro-2'-deoxyuridine (FUdR), induced changes in the expressed phenotype. Cells treated sequentially with Adriamycin and FUdR expressed a metastatic phenotype. The results also show short-term exposure of MCF-7 cells to either Adriamycin or FUdR rapidly increases, in a dose-dependent manner, the release of the angiogenic cytokine, interleukin-8(IL-8), which is released at consistently higher levels in metastatic cell lines. Cell populations surviving a single treatment with either one or both of these chemotherapeutic agents continue to stably release IL-8. Survivors of sequential treatment with Adriamycin and FUdR (MCF-7 A/F) release the most IL-8 and express the greatest phenotypic variance from the parental, MCF-7 cells. Parental MCF-7 cells and MCF-7 A/F cells both form primary tumors when used in an orthotopic tumor model; however, the MCF-7 A/F tumors have a more rapid initial growth phase in situ and give rise to spontaneous lung metastases within 10 weeks. A cell line that is established from lung metastases releases more IL-8, has a higher cloning efficiency, and forms looser colonies in monolayer than do their parental cells. These experiments indicate the in vitro exposure of tumor cells to chemotherapeutic agents either selects more aggressive cells or enhances the metastatic potential of the surviving cells.

Epidermal growth factor receptor and transforming growth factor alpha expression in papillary and nonpapillary renal cell carcinoma: correlation with metastatic behavior and prognosis.

Papillary renal carcinomas are a cytogenetically unique subset of renal carcinomas that have been reported to be clinically less aggressive. We have examined 19 papillary tumors for immunohistochemical expression of the epidermal growth factor receptor (EGF-R) and its ligand, transforming growth factor alpha (TGF-alpha). EGF-R and TGF-alpha expression was also studied in 149 nonpapillary tumors and 7 mixed papillary/solid tumors. EGF-R and TGF-alpha expression were compared to histology, stage, metastatic behavior, and survival. Formalin-fixed, paraffin-embedded nephrectomy specimens collected between 1977 and 1986 were stained with antibodies to EGF-R and TGF-alpha. Patients with papillary tumors were found to present with earlier stage disease and had significantly longer survival. Papillary tumors had a significantly lower rate of EGF-R positivity than solid pattern tumors (21% versus 73%, P < 0.001). Intermediate or strong cell membrane immunoreactivity for EGF-R was associated with high tumor grade and poor disease-specific survival. EGF-R positivity in the primary tumor was associated with the presence of metastatic disease and with metastatic spread to lung versus bone. Tumor parenchymal TGF-alpha staining was present in 50% of the cases and was not associated with stage or grade. Unrelated to tumor parenchymal TGF staining, tumor vessels stained for TGF-alpha in 56% of the cases. Vessel TGF-alpha staining was absent in papillary tumors (P < 0.001). The improved clinical behavior of papillary tumors as compared to nonpapillary renal tumors may be related, in part, to their relatively lower levels of EGF-R expression.

Male donor-derived cells in the brains of female sex-mismatched bone marrow transplant recipients: a Y-chromosome specific in situ hybridization study.

In five female bone marrow transplant (BMT) recipients of sex-mismatched donor marrow, Y-chromosome specific in situ hybridization was performed on formalin-fixed, paraffin-embedded sections of the medulla to detect the male donor marrow-derived cells. Y-chromosome-bearing cells (Y-cells), thereby donor-derived, were matched with leukocyte common antigen (LCA)-reactive cells in adjacent sections immunostained with anti-LCA antibody. Y-cells included mononuclear leukocytes (MNL) within the vessel lumen and infiltrating the perivascular space and parenchyma, and "perivascular cells." We have, therefore, concluded that donor marrow-derived MNL, though limited in number, do enter the normal-appearing brain and can transform to "perivascular cells" in human BMT recipients. It remains, however, to be confirmed whether MNL entering the normal adult CNS parenchyma transform to ramified microglia.

Renin expression in renal ablation.

To determine whether expression of the renin-angiotensin system (RAS) is influenced by the degree of renal ablation, male Sprague-Dawley rats underwent uninephrectomy, 1 1/3 nephrectomy, or sham operation. Renin and angiotensinogen messenger RNA (mRNA) were not different among the three groups 2 weeks after surgery. The time course of expression of renin mRNA after 1 1/3 nephrectomy showed no difference versus controls at 2 and 4 weeks and a decrease at 6 weeks after surgical ablation. Because nephrons adjacent to the infarcted area in the 1 1/3 nephrectomy may be hypoperfused and a source of increased renin synthesis, intrarenal distribution of tissue renin content, renin mRNA, and immunostainable renin were examined in separate groups of rats subjected to 1 1/3 nephrectomy. The kidney was divided into two pieces, one containing the scar and scar-adjacent tissue and the other portion the tissue distant from the scar. Tissue renin content, renin mRNA, and immunostainable renin were significantly greater in the scar-adjacent tissue compared with the nonscar tissue. Immunoreactive renin was seen in the juxtaglomerular apparatuses as well as in vascular elements proximal to the juxtaglomerular apparatus and within mesangial cells of some glomeruli of the scar-adjacent tissue. In conclusion, immunostainable renin, tissue renin content, and renin mRNA were increased in scar-adjacent tissue after 1 1/3 nephrectomy. We speculate that this unique scar-associated redistribution of renin may play a pathophysiological role in the progression of renal disease.

Clinical characteristics of post-transplant lymphoproliferative disorders.

PURPOSE: To study the histopathologic findings, clinical course, and therapeutic outcome of patients who developed a lymphoproliferative disorder after undergoing solid organ transplantation. PATIENTS AND METHODS: A series of 26 patients who developed a lymphoproliferative disorder after solid organ transplant during a 27-year period were studied. RESULTS: The 26 patients ranged in age from 6 to 68 years (median 42 years). The lymphoproliferative disorder was diagnosed from 1 to 211 months (median 80 months) after transplantation. The type of transplant was kidney (n = 21), heart or heart-lung (n = 4), or liver (n = 1). Most patients received azathioprine and prednisone, in addition to antilymphocyte globulin or cyclosporine, for post-transplant immunosuppression. Eight patients had lymphoma that could be classified according to the International Working Formulation (IWF-F, IWF-G, IWF-H). Sixteen patients had polymorphic lymphoma, and 2 patients were classified as having polymorphic lymphoid hyperplasia. Patients were staged by the Ann Arbor staging system. Nine patients had stage I disease, 4 stage II, 6 stage III, and 7 stage IV. Central nervous system, lung, or marrow involvement was present in 27%, 23%, and 14% of patients, respectively. In the 17 patients studied, immunophenotype was monoclonal B-cell (n = 12), malignant T-cell (n = 2), or polyclonal B-cell (n = 3). The initial therapeutic approach was generally a reduction in immunosuppression, but, thereafter, the approach to therapy varied. In patients with localized disease, surgical excision and/or involved field radiotherapy were utilized as applicable. For patients with more extensive disease, other approaches such as high-dose acyclovir, combination chemotherapy, or alpha interferon were utilized. Overall, 15 of 26 patients (58%) responded to systemic therapy or were rendered disease-free either by surgery or radiation, including 8 (31%) with a complete remission (CR). Only 3 of 9 patients responded to chemotherapy, whereas 4 of 13 patients responded to acyclovir (including 3 patients who experienced CR). Remission duration ranged from 8 to 122 months (median 32+ months). Twenty-one of 26 patients (81%) have died. Survival ranged from less than 1 to 122 months (median 14 months). CONCLUSION: The outcome of patients with post-solid organ transplant lymphoproliferative disorders is poor, and the optimal approach to therapy is not clear. Newer therapeutic approaches are thus needed to improve the outcome of these patients.

Pulmonary cytolytic thrombi: a previously unrecognized complication of bone marrow transplantation.

Lung injury is a frequent and severe complication of bone marrow transplantation (BMT). Over the past 5 years we have recognized a new noninfectious pulmonary complication of allogeneic BMT in 12 patients, presenting with fever, pulmonary nodules on chest computed tomography, and distinctive histopathologic appearance descriptively termed "pulmonary cytolytic thrombi" (PCT). All but one patient were children transplanted for malignant (9) and nonmalignant (3) conditions. Ten of the patients had active graft-versus-host disease (GVHD) of skin, bowel, or both at the time of diagnosis of the PCT. In all cases occlusive vascular lesions were present, most of them associated with hemorrhagic infarcts. The endothelial cell layer was discontinuous in all cases stained with antibody to CD31. The thrombi had entrapped recognizable leukocytes and CD45-positive cell fragments embedded in a tenacious basophilic material. The symptoms and radiologic findings resolved in weeks to months. PCT may represent a previously unrecognized form of pulmonary acute GVHD.

Placental alkaline phosphatase immunoreactivity in testicular germ-cell neoplasms.

We analyzed the sensitivity of a polyclonal antibody to placental alkaline phosphatase (PLAP) in labelling testicular germ-cell neoplasms, by utilizing the peroxidase-antiperoxidase technique. The immunoreactivity of 89 germ-cell tumors for PLAP was as follows: 98% of cases with seminomatous elements were PLAP-positive; 97% of embryonal carcinomas and 85% of endodermal sinus tumors also showed reactivity. Cytotrophoblastic cells were focally immunoreactive in one of two cases with choriocarcinomatous elements. Staining for PLAP was strongest and most diffuse in seminomas. Intratubular germ-cell neoplasia (ITGCN) or carcinoma in situ was present in 53 (84%) of 63 specimens that had adjacent seminiferous tubules available for evaluation; PLAP was demonstrated in 98% of these. In addition, the germ-cell elements in 11 gonadoblastomas were immunoreactive for PLAP. One of 17 cases of undescended testes had ITGCN that was also strongly immunoreactive, but the remaining 16 cases were negative. Five dysgenetic gonads without ITGCN were studied, and one was immunoreactive for PLAP. Three testicular biopsy specimens from infertile men without ITGCN were PLAP-negative. Our findings indicate that PLAP is a highly sensitive marker for seminomas, for the majority of embryonal carcinomas and endodermal sinus tumors of the testis, and for ITGCN.

Intermediate trophoblast in germ cell neoplasms.

One-hundred-twenty-four germ cell tumors and 11 gestational choriocarcinomas were assessed immunohistochemically for the presence of the following placental markers: human chorionic gonadotrophin, human placental lactogen, and pregnancy-specific beta-1 glycoprotein, and for the expression of cytokeratin. A total of 40 cases contained syncytial trophoblastic cells, large mononuclear cells, or both. These cases included all gestational choriocarcinomas and choriocarcinomatous foci in 11 mixed germ cell tumors, 14 embryonal carcinomas, and four seminomas. Syncytial trophoblastic cells reactive for cytokeratin were identified in all choriocarcinomas, 12 embryonal carcinomas, and two seminomas. Human placental lactogen-reactive syncytial trophoblastic cells were observed in nine gestational choriocarcinomas, 10 choriocarcinomatous foci in mixed germ cell tumors, four embryonal carcinomas, and one seminoma. Pregnancy-specific beta-1 glycoprotein-reactive syncytial trophoblastic cells were seen in 10 gestational choriocarcinomas, all choriocarcinomatous foci in mixed germ cell tumors, 11 embryonal carcinomas, and one seminoma. Cytotrophoblasts, as expected, were identified only in choriocarcinomas. Cytokeratin-reactive cytotrophoblast was seen in all gestational choriocarcinomas and 10 choriocarcinomatous foci in mixed germ cell tumors. Human chorionic gonadotrophin-reactive cytotrophoblast was observed in two gestational choriocarcinomas and three choriocarcinomatous foci in mixed germ cell tumors. Cytotrophoblast was uniformly nonreactive for human placental lactogen and pregnancy-specific beta-1 glycoprotein. Cytokeratin-reactive large mononuclear cells were observed in 10 gestational choriocarcinomas, all choriocarcinomatous foci in mixed germ cell tumors, five embryonal carcinomas, and three seminomas. Human placental lactogen-reactive large mononuclear cells were identified in nine gestational choriocarcinomas, seven choriocarcinomatous foci in mixed germ cell tumors, one embryonal carcinoma, and one seminoma. Pregnancy-specific beta-1 glycoprotein-reactive large mononuclear cells were present in 10 gestational choriocarcinomas, 10 choriocarcinomatous foci in mixed germ cell tumors, two embryonal carcinomas, and two seminomas. Because of morphologic and immunohistochemical similarities of large mononuclear cells with intermediate trophoblast of the normal placenta and gestational trophoblastic neoplasms, we propose that the large mononuclear cells in gonadal and extragonadal germ cell neoplasms are equivalent to the intermediate trophoblast.

Melanotic neuroectodermal tumor of infancy. A reexamination of a histogenetic problem based on immunohistochemical, flow cytometric, and ultrastructural study of 10 cases.

Ten cases of melanotic neuroectodermal tumor of infancy (MNTI) were studied. There were nine males and one female ranging in age from 2 weeks to 10 months; one patient was 8 years old. Sites of origin were the maxilla (five), epididymis (two), mandible (one), skull (one), and soft tissues of the cheek (one). Six tumors recurred from 1 to 18 months after diagnosis. One patient had widespread dissemination. Electron microscopic study of four cases showed cells with melanosomes at various stages of maturation, and cells with neuroblastic features, including neurosecretory granules and cytoplasmic processes. Nine cases of MNTI were studied immunohistochemically. Small neuroblastic cells and large cells in all cases were reactive for neuron-specific enolase (NSE), synaptophysin, HMB45, and dopamine-beta-hydroxylase, large cells in all cases and few small cells were reactive for cytokeratin (CK) and vimentin (VIM). Epithelial membrane antigen was observed in large cells in three cases, four cases expressed Leu 7 antigen, three were focally positive for glial fibrillary acidic protein, one for desmin, and one for chromogranin. All cases were nonreactive for retinol-binding protein, neurofilaments, alpha-fetoprotein, S-100 protein, and carcinoembryonic antigen. Five normal adult retinas were studied similarly; the pigmented epithelium of the retina was reactive for CK, VIM, HMB45, NSE, and S-100. DNA study, performed in eight tumors, revealed aneuploidy in two (DNA index = 1.7 and 1.8); these cases recurred within 1 month. No differences were observed according to site or behavior. MNTI is a primitive neuroectodermal tumor with polyphenotypic expression of neural and epithelial markers, melanin production, occasional glial, and rhabdomyoblastic differentiation, and no photoreceptor differentiation. It probably represents a dysembryogenetic neoplasm that recapitulates the retina at 5 weeks of gestation.

So-called sclerosing hemangiomas of lung. An immunohistochemical study supporting a respiratory epithelial origin.

Sclerosing hemangiomas are benign pulmonary neoplasms. They were initially believed by Liebow and Hubbell to be of endothelial origin; however, subsequent ultrastructural studies have suggested an alveolar pneumocyte and mesothelial derivation. Using a panel of various antibodies on eight cases, the authors found that sclerosing hemangiomas expressed cytokeratin (seven cases), epithelial membrane antigen (seven cases), carcinoembryonic antigen (five cases), vimentin (seven cases), surfactant apoprotein (eight cases), and Clara cell antigen (five cases). These results support the hypothesis that sclerosing hemangiomas represent an epithelial tumor showing simultaneous bronchiolar epithelial and alveolar pneumocyte differentiation.

Chronic renal allograft rejection in the first 6 months posttransplant.

Between May 1, 1986 and May 31, 1992 at the University of Minnesota, we interpreted 129 renal allograft biopsy specimens (done in 48 grafts during the first 6 months posttransplant) as showing changes consistent with chronic rejection. For this retrospective analysis, we reexamined these biopsies together with clinical information to determine: (a) whether a diagnosis other than chronic rejection would have been more appropriate, (b) how early posttransplant any chronic rejection changes occurred, and (c) if the diagnosis correlated with outcome. We found that (1) chronic rejection is uncommon in the first 6 months posttransplant; it was documented in only 27 (2.4%) of 1117 renal allografts and was preceded by acute rejection in all but 3 recipients (for these 3, the first biopsy specimen showed both acute and chronic rejection). (2) Chronic vascular rejection was seen in 1 recipient as early as 1 month posttransplant; the incidence increased over time and was associated with an actual graft survival rate of only 35%. (3) The most frequent cause of arterial intimal fibrosis in the first 6 months posttransplant was arteriosclerotic nephrosclerosis (ASNS) of donor origin. Long-term graft function for recipients with ASNS was 67%. (4) Early-onset ischemia or thrombosis was seen in 14 recipients and predicted poor outcome: only 35.7% of these recipients had long-term graft function. (5) Cyclosporine (CsA) toxicity was implicated in only 3 recipients, who had mild diffuse interstitial fibrosis in association with elevated CsA levels. Other variables (including systemic hypertension, urinary tract infection, obstructive uropathy, neurogenic bladder, cobalt therapy, and recurrent disease) were not significantly associated with chronic renal lesions in the first 6 months posttransplant. A significant number of biopsies were originally interpreted as showing chronic rejection, but the diagnosis was changed upon reevaluation in conjunction with clinical data. We conclude that many factors coexist to produce chronic lesions in biopsies during the first 6 months posttransplant, so clinical correlation is needed before establishing a diagnosis of chronic rejection.

Evidence that 15-deoxyspergualin inhibits natural antibody production but fails to prevent hyperacute rejection in a discordant xenograft model.

Preventing hyperacute rejection (HAR) is a difficult and unsolved problem in xenotransplantation. This may be due, in part, to a lack of therapies that can suppress production of natural antibodies (NA), which are thought to be critical mediators of HAR. This study examined the effect of 15-deoxyspergualin (DSPG) and splenectomy (Spx) on NA production and return of NA after plasma exchange (PE) in a discordant species combination (strain 2 guinea pig to Lewis rat). A dose of 5 mg/kg/day DSPG + Spx significantly reduced Lewis rat anti-guinea pig NA titer after one week of therapy. Antibody titer was not significantly reduced in rats treated with splenectomy alone. PE alone acutely depleted NA titers; however, complete rebound was seen in 48 hr. When PE was performed in rats treated with DSPG + Spx, an additional significant NA reduction occurred; no rebound 24-48 hr after PE was seen. Except for a 20% reduction in body weight, no serious complications occurred in DSPG + Spx recipients. Despite a profound NA titer reduction, treatment with DSPG, Spx, and PE did not prolong guinea pig cardiac xenograft survival in a clinically significant fashion. Immunopathological study of rejected cardiac xenografts revealed no antibody deposition but persistent complement deposition on vascular endothelium. We conclude that DSPG + Spx effectively inhibits synthesis of rat anti-guinea pig NA, that further NA titer reduction can be achieved with the addition of PE, and that DSPG + Spx prevents post-PE antibody rebound. We also conclude that the limited prolongation in cardiac xenograft survival achieved, despite marked suppression of NA, supports a complement-mediated mechanism of HAR in our animal model.

Diffuse lymphoplasmacytic acalculous cholecystitis: a distinctive form of chronic cholecystitis associated with primary sclerosing cholangitis.

Inflammation of the gallbladder is known to occur in patients with primary sclerosing cholangitis (PSC). However, the histological features of this form of cholecystitis have not been adequately defined. The aim of this study was to compare the inflammatory lesions of PSC-associated cholecystitis with those present in other cholecystopathies. The cases consisted of 11 gallbladders from patients with PSC who underwent liver transplantation. As controls, gallbladders from liver transplant patients with primary biliary cirrhosis (n = 4) and other chronic nonbiliary hepatopathies (n = 8), and 13 cholecystectomies from patients with chronic cholecystitis with (n = 10) and without (n = 3) lithiasis, were studied. The following histological features were tabulated on coded slides: presence, depth of involvement, and distribution of the inflammatory infiltrate, predominant cell type, presence of lymphoid aggregates, epithelial damage, metaplastic changes (pyloric or intestinal), fibrosis, smooth muscle hypertrophy, and presence of Rokitansky-Aschoff sinuses. At variance with the wide range of histological abnormalities present in other forms of chronic cholecystitis, most PSC-related cholecystitis showed a diffuse infiltrate (6 of 11) rich in plasma cells (6 of 11) predominantly confined to the lamina propria (9 of 11). The combination of these three features was present exclusively in PSC (5 of 11 PSC cholecystitis compared with 0 of 25 controls; P = .001). In conclusion, this study suggests that a characteristic form of cholecystitis may develop in patients with PSC.

Medullary adenocarcinoma of the colon: clinicopathologic study of 11 cases.

Colonic carcinomas with minimal or no glandular differentiation are a heterogeneous group of neoplasms which differ in their histologic appearance, clinical features, prognosis and molecular characteristics. Since 1990, we prospectively identified 11 patients with a predominantly solid (nonglandular) adenocarcinoma of the colon for which the term medullary adenocarcinoma of the colon (MAC) is proposed. The clinical, histological, histochemical, and immunohistochemical features of these neoplasms were studied. All patients with MAC were women with tumors in the cecum or proximal colon. Histological analysis showed nests or trabeculae of regular small to medium-sized cells with moderate amounts of eosinophilic cytoplasm; some cells contained mucin vacuoles. The nuclei had an open chromatin pattern and exhibited prominent nucleoli. Lymphatic permeation was present in most cases. Immunohistochemical reactions were positive for cytokeratin, carcinoembryonic antigen, and epithelial membrane antigen. Despite its histological resemblance with endocrine tumors, MAC is negative for endocrine markers. Of the eight patients for whom follow-up is available, four patients (two Dukes B and two Dukes C) are alive and well 1 to 4 years after surgery, one patient (Dukes C) died of tumor, one patient is alive with liver metastasis 4 years after surgery, and two patients died in the postoperative period. MAC appears to be a distinctive clinicopathologic entity. This tumor should be distinguished from other more aggressive, nonglandular tumors of the colon.

Malignant mixed müllerian tumors: an immunohistochemical study of 47 cases, with histogenetic considerations and clinical correlation.

Forty-seven cases of malignant mixed müllerian tumors were reviewed histologically and studied immunohistochemically with three major objectives: to analyze the histogenetic relationship between the carcinomatous and sarcomatous components of these neoplasms, to ascertain the practical role of immunohistochemical studies in diagnosis and classification, and to determine the prognostic significance of immunohistochemically verified rhabdomyoblastic and neuroendocrine differentiation. Epithelial differentiation (cytokeratin and/or epithelial membrane antigen expression) was confirmed in all carcinomatous components; within the sarcomatous areas, it was identified among individual cells (60% of cases) and within poorly formed clusters of cells (57% of cases). There was a statistically significant tendency for concordant expression of alpha-1-antichymotrypsin, Leu-M1, S-100, Leu-7, and neuron-specific enolase between the carcinomatous and sarcomatous components of individual cases. These two findings provide evidence of common origin for the sarcomatous and carcinomatous components of these neoplasms. Histologic review of metastases in 21 cases revealed a biphasic composition in the majority of metastatic lesions (62%), another feature that further supports a common origin for the two components. From a practical standpoint, immunohistochemistry may be helpful in accentuating the biphasic pattern of these neoplasms and in verifying the presence of rhabdomyoblastic differentiation. In most cases, however, careful morphologic examination and thorough sampling will suffice for correct diagnosis and subclassification. The presence of heterologous, rhabdomyoblastic, or neuroendocrine differentiation did not have a statistically significant influence on survival; the last of these was associated with a tendency for a more rapidly fatal course.

Distribution and immunophenotype of the inflammatory cell population in the benign lymphoepithelial lesion (Mikulicz's disease).

Benign lymphoepithelial lesion (BLL) is an autoimmune process characterized by swelling and diffuse inflammation of the major salivary glands. Autoantibodies have been isolated from lymphocyte cultures obtained from affected salivary glands, but the pathogenesis is still unknown. Previous studies have shown that the predominant population of inflammatory cells is represented by helper T cells, with only brief mention of the B cell population. Twenty-five surgical specimens from patients with BLL were studied immunohistochemically. Antisera used included monoclonal antibodies LN-1 and LN-2 for B cells, LN-3 for cells expressing human leukocyte antigen-DR (HLA-DR) antigens, UCHL-1 for T cells, Leu-7 for natural killer (NK) cells, and T suppressor lymphocytes and the polyclonal antibody to S100 protein for dendritic cells. A peculiar distribution of the inflammatory infiltrate was observed in all cases, characterized by the presence of very irregular "germinal centers" with pseudopod-like extensions surrounding epimyoepithelial islands. Lymphoid cells in this location were reactive with LN-1 and LN-2 antibodies. These structures were surrounded by a "mantle" of mixed small B and T lymphocytes. A well-defined "interfollicular" zone was composed of cells strongly reactive with UCHL-1 and LN-3 antibodies, indicating the presence and activation of T cells. Dendritic cells defined by S100 and LN-2 reactivity were intermixed with epimyoepithelial cells, and were identified in 18 cases. Epithelial expression of HLA-DR antigens was restricted to inflamed areas. In contrast to previous reports denying the presence of Leu-7-positive cells in these lesions, cells reactive for this antibody were identified in 13 of 20 cases, predominantly within germinal centers. The presence of dendritic cells, complex organization of the inflammatory infiltrate into well-defined B cell proliferation centers and activated interfollicular T areas, and the abnormal expression of HLA-DR antigens in epithelial cells support an antibody-mediated destruction of the epithelial cells in this disease.

Synovial sarcoma: ultrastructural study and immunohistochemical analysis by a combined peroxidase-antiperoxidase/avidin-biotin-peroxidase complex procedure.

To analyze the purportedly epithelial features of synovial sarcoma, the antigenic profiles of 20 of these neoplasms (including 12 of the monophasic type) were studied by three different immunohistochemical techniques, and the results were correlated with ultrastructural observations in 10 cases. All of the biphasic tumors were immunoreactive for the epithelial markers epithelial membrane antigen (EMA) and cytokeratin (CK) and also had ultrastructural features of epithelial differentiation. In contrast, only one of five monophasic tumors had electron microscopic features suggestive of epithelial differentiation, but eight of the 12 were immunoreactive for CK or EMA by a procedure combining the peroxidase-antiperoxidase and avidin-biotin-peroxidase complex methods. It is concluded that synovial sarcoma, including the monophasic variant, is a mesenchymal tumor with epithelial features. Immunohistochemical studies are more sensitive than ultrastructural analysis for documenting epithelial differentiation.