ABSTRACT
AIMS: To establish the conditions for protein tyrosine phosphatase gamma (PTPgamma) detection in paraffin tissues using two antibodies raised against its NH(2)- (anti-P4) and COOH-termini (gammaTL1); to analyse its expression in normal tissues and to perform an initial screening of neoplastic tissues. METHODS AND RESULTS: Membranous and/or cytoplasmic PTPgamma expression was detected in the majority of epithelial cell types and in endocrine cells, with the highest expression in adrenal medulla, endocrine cells of the gastrointestinal tract and pancreatic islets. Both antibodies stained the thyroid follicular epithelium, but only anti-P4 antibody stained the colloid matrix, suggesting shedding/secretion of the PTPgamma extracellular domain. Marked loss of PTPgamma immunoreactivity was detected in subsets of ovarian (21%), breast (56%) and lung (80%) neoplasms. Conversely, cytoplasmic positivity was found in 37% of lymphomas, mainly of high-grade histotypes, while normal lymphocytes were negative. Brain tissue showed PTPgamma expression in a few neuronal and glial elements and PTPgamma was overexpressed in the majority of high-grade astrocytomas. CONCLUSIONS: We have analysed PTPgamma expression in archival paraffin-embedded tissues for the first time, demonstrating particularly high expression in endocrine cells and both down- and up-regulation in neoplasia, the latter possibly reflecting the undifferentiated state of the neoplastic cells, suggesting a complex role for this phosphatase.
Subject(s)
Biomarkers, Tumor/metabolism , Neoplasms/enzymology , Nerve Tissue Proteins/metabolism , Protein Tyrosine Phosphatases/metabolism , Receptors, Cell Surface/metabolism , Down-Regulation , Endocrine System/cytology , Endocrine System/enzymology , Female , Fluorescent Antibody Technique, Indirect , Gene Expression Regulation, Neoplastic , Humans , Immunoenzyme Techniques , In Situ Hybridization , Male , Neoplasms/genetics , Neoplasms/pathology , Nerve Tissue Proteins/genetics , Protein Tyrosine Phosphatases/genetics , RNA, Messenger/metabolism , RNA, Neoplasm/analysis , Receptor-Like Protein Tyrosine Phosphatases, Class 5 , Receptors, Cell Surface/genetics , Up-RegulationABSTRACT
The chromatin pattern in nuclei from breast ductal proliferative lesions was quantitatively evaluated with the objective of deriving measures of tumor progression. A total of 110 cases were analyzed. There were 38 cases of normal tissue or benign proliferative lesions, 41 cases of ductal carcinoma in situ (DCIS), and 31 cases of microinfiltrating DCIS and of infiltrating cancer. A total of 9424 nuclei were analyzed. High-resolution images were digitally recorded. For each nucleus, 93 karyometric features descriptive of the spatial and statistical distribution of the nuclear chromatin were computed. Data analysis included establishing a profile of relative deviations of each feature from "normal," called the nuclear signature, and of lesion signatures as well as of trends of lesion progression. Two trends of evolution could be discerned: one from normal to hyperplasia, atypical hyperplasia, and comedo DCIS as representative of high-grade lesions; and the other from normal to hyperplasia to cribriform DCIS, solid DCIS, and infiltrating cancer, representing lower grade lesions. The nuclei in microinfiltrating foci are distinctly different from nuclei in high-grade comedo DCIS. The nuclei in microinfiltrating foci have a statistically significantly lower nuclear abnormality. They may represent outgrowing clones.
Subject(s)
Breast Neoplasms/pathology , Carcinoma in Situ/pathology , Carcinoma, Ductal, Breast/pathology , Carcinoma, Intraductal, Noninfiltrating/pathology , Breast/pathology , Cell Nucleus/pathology , Female , Humans , Hyperplasia/pathology , Image Processing, Computer-Assisted , PrognosisABSTRACT
The evaluation of progressive morphological changes, with 93 morphometric parameters in tissue lesions representative of ductal breast cancer progression, has been performed in order to define in great detail the profile of chromatin texture (nuclear signature) changes. A gradual, distinctive increase in nuclear signature alterations from hyperplasia to infiltrating carcinoma has been found. The nuclear signatures' analysis of microinfiltrating foci in comedo DCIS showed sharp differences compared with those of comedo DCIS they derived from: these foci consist of cells with smaller and also more homogeneous nuclei. Opposite to the prominent heterogeneity of those of comedo DCIS: they appear to express a reduced clonality in the new, more progressed, cell population. Digital analysis of chromatin patterns seems to be useful, beyond mere extraction of individual features of value, in getting objective data for individual grading and prognosis of breast cancer.
Subject(s)
Breast Neoplasms/pathology , Carcinoma, Intraductal, Noninfiltrating/pathology , Cell Nucleus/pathology , Image Cytometry/methods , Chromatin/pathology , Disease Progression , Female , Humans , Hyperplasia/pathology , Image Processing, Computer-AssistedABSTRACT
AIMS: The objective of this study is to derive highly specific nuclear signatures (NS's) for the characterization of nuclei of ductal breast epithelium in proliferative lesions and in situ cancers in order to evaluate if nuclear structural changes are able to describe the main events of ductal cancer progression and if the method can be used for objective grading. METHODS: A total of 82 different features descriptive of the nuclear chromatin patterns were computed in nuclei from normal glandular breast tissue, florid hyperplasia, and ductal carcinoma in situ (DCIS) and of DCIS with microinfiltration. The feature values were arranged to form a profile or signature. Measures of difference to a standard profile derived from normal glandular breast tissue were defined. One may then compute a standardized distance measure for a nucleus from "normal". Lesions can be characterized in the same manner, on the basis of the mean profile for all of their nuclei, and on the basis of the distribution of distances of their constituent nuclei from normal. RESULTS: The selected histopathologic patterns on which the diagnostic categories for DCIS are based were found to have corresponding distinctive patterns in the chromatin of the lesion's nuclei. A monotonic trend of ductal neoplastic progression was found. In addition, lesions histologically assessed as belonging to the same diagnostic category were found to offer substantially different distribution patterns. CONCLUSIONS: The full utilization of nuclear texture features allows the derivation of highly specific signatures for nuclei so that a reproducible grading can be performed for prognostic purposes.
Subject(s)
Breast Neoplasms/pathology , Carcinoma in Situ/pathology , Carcinoma, Ductal, Breast/pathology , Cell Nucleus/pathology , Breast/pathology , Cell Division , Chromatin/pathology , Disease Progression , Female , Humans , Hyperplasia , Image Cytometry , Image Processing, Computer-AssistedABSTRACT
The effect of eradication of Helicobacter pylori on early stage gastric low-grade MALT lymphoma in 76 patients with follow-up of at least 1 year (12-63 months, mean 28) is reported. No regression was found in five cases after 12-48 months. In one case surgical resection detected the involvement of perigastric lymph nodes overlooked by endoscopic ultrasonography (EUS). Neither progression of the disease nor a high-grade component was documented by repeated gastric mappings, EUS and complete stagings in the other four cases. After histological remission five relapses of low-grade and one relapse of high-grade MALT lymphoma were found 12-48 months after eradication. Subsequent histological remission, without any additional therapy, was found in three relapsed cases. A rapid and persistent histological remission was obtained in 56 patients (73%). A late remission was observed in six cases. Monoclonal remission was found in half of the patients and was frequently delayed. Persistent monoclonality was associated with histological remission in the vast majority of patients. Our data confirm H. pylori eradication as the first choice therapy for early stage gastric low-grade MALT lymphoma and recommend extensive bioptic mapping and endoscopic sonography both in the local staging and in the regression evaluation. The rare cases of late remission encourage us to wait for at least 1 year after eradication of H. pylori. Longer follow-up studies will clarify the meaning of histological relapse/persistence and late remission. The study of non-responder cases could show us a step in lymphomagenesis.
Subject(s)
Helicobacter Infections/drug therapy , Lymphoma, B-Cell, Marginal Zone/pathology , Stomach Neoplasms/pathology , Aged , Aged, 80 and over , Anti-Bacterial Agents/therapeutic use , Evaluation Studies as Topic , Female , Helicobacter Infections/complications , Helicobacter Infections/microbiology , Helicobacter pylori/isolation & purification , Humans , Italy , Lymphoma, B-Cell, Marginal Zone/drug therapy , Lymphoma, B-Cell, Marginal Zone/microbiology , Male , Middle Aged , Recurrence , Stomach Neoplasms/drug therapy , Stomach Neoplasms/microbiology , Treatment OutcomeABSTRACT
The presence of a restrictive atrial septal defect in hypoplastic left heart syndrome represents a surgical emergency and may negatively affect survival after operation. A neonate with such a disease association, requiring septectomy upon birth developed intractable respiratory failure due to congenital pulmonary lymphangiectasis. The therapeutic implications of this rare pathologic condition are discussed.
Subject(s)
Heart Septal Defects, Atrial/complications , Hypoplastic Left Heart Syndrome/complications , Lung Diseases/complications , Lung/abnormalities , Lymphangiectasis/complications , Fatal Outcome , Heart Septal Defects, Atrial/pathology , Heart Septal Defects, Atrial/therapy , Humans , Hypoplastic Left Heart Syndrome/pathology , Hypoplastic Left Heart Syndrome/therapy , Infant, Newborn , Lung Diseases/congenital , Lung Diseases/pathology , Lung Diseases/therapy , Lymphangiectasis/congenital , Lymphangiectasis/pathology , Lymphangiectasis/therapy , MaleABSTRACT
Current analytic methodologies allow the extraction, even from small tumor masses, of extensive information on the biologic characteristics of malignant lesions, such as tumor aggressivity, metastatic potential, drug resistance, and host interactions. Clinical practice now offers a wide range of therapeutic strategies. Information technological advances offer the opportunity to refer to very large data bases of patient anamnestic data, response to treatment and clinical outcome. There is a need to formulate therapy and prognosis for each individual case. Case based reasoning is a knowledge based methodology where the outcome for complex situations can be predicted by referring to a large data base of cases of known outcomes. The preliminary data obtained from this study suggest that case based reasoning may offer a promising approach to individual targeted prognosis.
Subject(s)
Breast Neoplasms/classification , Carcinoma, Ductal, Breast/classification , Breast Neoplasms/diagnosis , Breast Neoplasms/epidemiology , Carcinoma, Ductal, Breast/diagnosis , Carcinoma, Ductal, Breast/epidemiology , Case Management , Cell Nucleolus/pathology , Cell Nucleus/pathology , Data Interpretation, Statistical , Decision Making , Female , Follow-Up Studies , Humans , Information Storage and Retrieval , Italy/epidemiology , Prognosis , Proliferating Cell Nuclear Antigen/analysis , Treatment OutcomeABSTRACT
The diagnostic subjective assessment of ductal premalignant proliferative lesions and in situ carcinoma of the breast produces unsatisfactory results. Since the phenotypical cell changes in tumour progression toward infiltrating cancer constitute a continuum, a grading on a continuous scale of values produces a more reliable and reproducible characterization. The diagnostic assessment for any individual patient may be expressed by a progression index (P.I.): its numerical values are based on the cellular changes measured in the individual cases. In this study, the progression index is based on two morphometric features, nuclear size and nucleolar area. In addition, the method presented may produce a ratio, stating the relative likelihood that each case represents one of the conventional diagnostic categories. Such a likelihood ratio may be obtained from the bivariate distribution of nuclear size and nucleolar area for the conventional diagnostic categories.
Subject(s)
Breast Neoplasms/pathology , Carcinoma in Situ/pathology , Carcinoma, Ductal, Breast/pathology , Precancerous Conditions/pathology , Breast Neoplasms/genetics , Carcinoma in Situ/genetics , Carcinoma, Ductal, Breast/genetics , Disease Progression , Humans , Microscopy, Video , Neoplasm Invasiveness , Precancerous Conditions/genetics , PrognosisSubject(s)
Breast Neoplasms/pathology , Breast/pathology , Carcinoma in Situ/pathology , Carcinoma, Ductal, Breast/pathology , Breast Neoplasms/chemistry , Carcinoma in Situ/chemistry , Carcinoma, Ductal, Breast/chemistry , Disease Progression , Female , Humans , Hyperplasia/pathology , Immunohistochemistry , Neoplasm Staging , Phenotype , Receptor, ErbB-2/analysisABSTRACT
Fifty-nine cases of Breast Epithelial Proliferative Lesions (BEPL) and Ductal Carcinoma in Situ (DCIS), were studied by image analysis, to evaluate the nuclear changes occurring in the conventional diagnostic categories of ductal hyperplasia, atypical ductal hyperplasia and DCIS with quantitative methods. Diagnosis reproducibility is the main practical problem of these breast lesions. In fact, with subjective methods, the reproducibility appears to be very low and precarious especially for clinical demands. The objective, quantitative evaluation of cell phenotypical changes should be the method for both practical diagnostic problems and study of ductal cancer progression. The distribution pattern of the data in the feature, obtained with quantitative analysis, strongly suggests a continuum of changes, indicating an evolutionary process of Breast Ductal Carcinoma (BDC) progression in its preinvasive stage. Each observed case may be characterised by its own cellular, objective alterations and a progressive trend toward BDC can be stated. Since the actual changes of the proliferative phenotypes can be measured, and the values are reproducible, karyometric measurement may allow an objective grading of individual cases.
Subject(s)
Breast Neoplasms/pathology , Carcinoma in Situ/pathology , Carcinoma, Ductal, Breast/pathology , Cell Transformation, Neoplastic/pathology , Adult , Aged , Cell Nucleus/pathology , Female , Fibrocystic Breast Disease/pathology , Humans , Hyperplasia/pathology , Image Processing, Computer-Assisted , Middle Aged , Receptor, ErbB-2/analysisABSTRACT
A case of intramammary solitary schwannoma (SS) (benign neurilemoma) diagnosed by fine-needle aspiration biopsy (FNAB) and supported by immunocytochemical study is reported. The tumor arose in the right breast of an 18-yr-old woman and was clinically and radiologically considered a fibroadenoma. The smears obtained by FNAB of the lump showed clusters of spindle-shaped cells and suggested a benign mesenchymal neoplasm. The presence of some structures reminiscent of Verocay bodies and the immunocytochemical reactivity for S-100 protein antiserum demonstrated the schwannian nature of the tumor and suggested the diagnosis of SS. The final histologic examination confirmed the cytologic diagnosis.
Subject(s)
Breast Neoplasms/pathology , Neurilemmoma/pathology , Adolescent , Biopsy, Needle , Breast Neoplasms/chemistry , Female , Follow-Up Studies , Humans , Immunoenzyme Techniques , Neurilemmoma/chemistry , Preoperative CareABSTRACT
Surgical splanchnicectomy for the relief of neoplastic pain is a palliative strategy in cases of unremovable pancreatic cancer. The first step in the achievement of satisfactory and long-lasting relief of pain is the correct identification of semilunar ganglia and splanchnic nerves during laparotomy. In this light, we tried to estimate the exact location, number, shape, and length of splanchnic nerves and ganglia in 15 corpses (mean age 39.9 years, range 21-74, F/M/ = 5/10). Right and left splanchnic nerves always pierce the diaphragm laterally to the crus. On the right side, the splanchnic nerve always enters the abdomen posterior to the inferior vena cava, on the right edge in 10%, on the middle in 73%, on the left in 17% of the cases. On the left side, the splanchnic nerve pierces the diaphragm strictly thickened to the left edge of the aorta in 66.6% of the cases, close to the left edge in 26.6%, and close to the right edge of the left adrenal gland in 6.8%. The right splanchnic nerve slides almost horizontally on the diaphragmatic bundles, and reaches an area delimited by the coeliac trunk and the superior mesenteric artery. The length of the right splanchnic nerve is 41 mm of the mean (range 20 to 55 mm): the thickness is between 4 and 6 mm. The left splanchnic nerve is shorter (mean 24 mm, range 15; 30 mm). The right splanchnic nerve varies from 2 to 6 ganglionar bodies and varies in size from 4.5 mm to 30 mm; the left nerve varies form 2 to 4 (sizes between 4 mm to 26 mm).(ABSTRACT TRUNCATED AT 250 WORDS)
Subject(s)
Algorithms , Pain Management , Pancreatic Neoplasms/surgery , Splanchnic Nerves/anatomy & histology , Splanchnic Nerves/surgery , Autopsy , Humans , Pain/etiology , Pancreatic Neoplasms/physiopathologyABSTRACT
The cellular composition of suppurative granulomas was investigated by the application of monoclonal and polyclonal antibodies to paraffin sections and compared with nonsuppurative, hypersensitivity-type granulomas. Macrophages, T cells, and dendritic cells showed a similar distribution in both types of granulomas. In addition to the presence of granulocytes, a major difference between suppurative granulomas and hypersensitive-type granulomas concerned their relationship with B lymphocytes. Hypersensitive-type granulomas were surrounded by small mantle B cells, but they did not contain any B lymphocytes. In contrast, variable numbers of B cells were found either at the periphery or in the center of suppurative granulomas. In view of their morphology (medium size, pale cytoplasm, irregular nuclear shape) and phenotype (L26 +/LN1 -/MB2 +/MT2 +) these B lymphocytes closely resembled monocytoid B cells. The monocytoid B cells might have a role in the recruitment of polymorphonuclear granulocytes and in the development of the necrosis, which occur within suppurative granulomas.
Subject(s)
B-Lymphocytes/pathology , Granuloma/pathology , Lymphadenitis/pathology , Acid Phosphatase/analysis , Alkaline Phosphatase/analysis , Antibodies, Monoclonal/analysis , B-Lymphocytes/chemistry , Biopsy , Carcinoembryonic Antigen/analysis , Cell Nucleus/ultrastructure , Cytoplasm/ultrastructure , Dendritic Cells/chemistry , Dendritic Cells/pathology , Elastin/analysis , Humans , Immunohistochemistry , Lymph Nodes/chemistry , Lymph Nodes/pathology , Macrophages/chemistry , Macrophages/pathology , T-Lymphocytes/chemistry , T-Lymphocytes/pathologyABSTRACT
A series of 36 human thymomas have been immunohistochemically analyzed using a panel of antibodies recognizing B-cell markers including CD20. Most thymomas exhibiting the cortical pattern, according to the criteria of Marino and Muller-Hermelink, were characterized by areas of medullary differentiation containing variable numbers of CD20+ B lymphocytes, thus mimicking the medulla of normal thymus. On the other hand, B cells were absent or rare in thymomas recognized as mixed using the same morphological criteria. Surprisingly, we observed in most mixed thymomas variable numbers of CD20+ spindle cells, characterized by long slender processes. Using double-marker analysis we could demonstrate the epithelial nature of these cells (expression of keratin and lack of lymphoid and B-cell-related markers). The immunoreactivity of thymoma epithelial cells with L26, an antibody widely used in the characterization of B-cell lymphomas, can represent a drawback of practical relevance in the differential diagnosis of mediastinal tumors.
Subject(s)
Antigens, CD/analysis , Antigens, Differentiation, B-Lymphocyte/analysis , B-Lymphocytes/immunology , Thymoma/immunology , Thymus Neoplasms/immunology , Antibodies, Monoclonal , Antigens, CD20 , B-Lymphocytes/pathology , Humans , Immunohistochemistry , Thymoma/pathology , Thymus Neoplasms/pathologyABSTRACT
In this study 27 transbronchial biopsy specimens obtained from patients with clinical and/or laboratory features suggestive for sarcoidosis were analysed with conventional morphology and immunohistochemistry comparing the sensitivity and reproducibility of the two methods. A limited panel of monoclonal antibodies recognizing epitopes resistant to conventional fixation and embedment procedures were used (CD45R0, CD68, anti-cheratin, anti-collagen IV). All specimens were independently observed by two different pathologists. On the basis of the recognition of bona-fide noncaseating granulomas, 9 cases were uniformly judged as positive, 10 cases as negative, but 8 cases were considered doubtful. Immunohistochemical analysis reliably demonstrated the presence of epithelioid cells in 3 of these cases and absence in 5. These data suggest that the use of a limited immunohistochemical analysis can significantly improve histological diagnosis of sarcoidosis on small transbronchial biopsies using conventional routine material.
Subject(s)
Biopsy , Sarcoidosis, Pulmonary/diagnosis , Antigens, CD/analysis , Antigens, Differentiation, Myelomonocytic/analysis , Collagen/analysis , Granuloma/diagnosis , Granuloma/immunology , Granuloma/pathology , Humans , Immunohistochemistry , Keratins/analysis , Leukocyte Common Antigens/analysis , Lung/immunology , Lung/metabolism , Lung/pathology , Lung Diseases/diagnosis , Lung Diseases/immunology , Lung Diseases/pathology , Reproducibility of Results , Sarcoidosis, Pulmonary/immunology , Sarcoidosis, Pulmonary/metabolism , Sarcoidosis, Pulmonary/pathology , Sensitivity and SpecificityABSTRACT
The calcium-binding protein calbindin-D (28 kD) has been analysed immunohistochemically in different human lymphoid tissues. Combined immunohistochemical staining showed that calbindin-D (28 kD) is expressed by only a proportion of dendritic cells within the light zone of germinal centres, where antigens in the form of immune complexes are trapped and presented to B lymphocytes. All other cell types including macrophages, interdigitating cells, and various lymphocyte populations were negative. The expression of calbindin-D in this functionally relevant subset of follicular dendritic cells could have a role in the regulation of proliferation and selection of memory B-cells by modulating the concentration of calcium ions. Calbindin-D may be a useful marker for analysing in situ the phases of follicular development in different physiological and pathological conditions.
Subject(s)
Dendritic Cells/chemistry , S100 Calcium Binding Protein G/analysis , Calbindins , Humans , Hyperplasia , Immunohistochemistry , Lymph Nodes/pathology , Sarcoidosis/metabolism , Toxoplasmosis/metabolismABSTRACT
HMB-45 (melanocytic cell-specific monoclonal antibody) immunoreactivity was investigated in 10 cases of angiomyolipoma (AML) (1 with massive regional lymph node involvement) of the kidney and detected in all of them. No HMB-45 immunoreactivity was found in other tumors of the region which can occasionally be confused with AML, such as renal cell carcinoma, Wilms' tumor, and retroperitoneal sarcoma (leiomyosarcoma and liposarcoma). These findings indicate that HMB-45 is not a melanocyte-restricted marker and suggest that its expression might be useful in distinguishing AML from other tumors of the kidney and retroperitoneum.
Subject(s)
Antibodies, Monoclonal/immunology , Biomarkers, Tumor/analysis , Hemangioma/immunology , Kidney Neoplasms/immunology , Lipoma/immunology , Melanocytes/immunology , Carcinoma, Renal Cell/diagnosis , Carcinoma, Renal Cell/immunology , Diagnosis, Differential , Hemangioma/diagnosis , Humans , Immunohistochemistry , Kidney Neoplasms/diagnosis , Lipoma/diagnosis , Retroperitoneal Neoplasms/diagnosis , Retroperitoneal Neoplasms/immunology , Sarcoma/diagnosis , Sarcoma/immunology , Wilms Tumor/diagnosis , Wilms Tumor/immunologyABSTRACT
HMB45 is a melanoma-specific monoclonal antibody that has found widespread use in diagnostic pathology. Recent reports, however, have suggested that this antibody may cross-react with a small number of carcinomas and other epithelial cells. The authors tested the hypothesis that these latter reports represent examples of false-positive immunostaining by comparing the immunostaining on breast, salivary gland, and lung tumors with the following: (1) a commercial ascites preparation of this monoclonal antibody; (2) a protein A-purified antibody preparation derived from ascites fluid; and (3) supernatant fluid obtained from the hybridoma cell line. The authors found that all examples of nonmelanoma immunostaining in the carcinomas tested were eliminated with the nonascites fluid preparations, whereas strong immunostaining of melanomas was retained. The authors conclude that contaminated commercial ascites fluid preparations of HMB45 may account for most, if not all, of the reports of nonmelanoma immunostaining with HMB45.
Subject(s)
Ascites/metabolism , Breast Neoplasms/metabolism , Lung Neoplasms/metabolism , Salivary Gland Neoplasms/metabolism , Antibodies, Monoclonal/immunology , Antibodies, Neoplasm/immunology , Ascites/immunology , Breast Neoplasms/diagnosis , Breast Neoplasms/pathology , Epithelium/metabolism , Epithelium/pathology , False Positive Reactions , Humans , Immunohistochemistry/methods , Lung Neoplasms/diagnosis , Lung Neoplasms/pathology , Melanoma/immunology , Salivary Gland Neoplasms/diagnosis , Salivary Gland Neoplasms/pathologyABSTRACT
The gene encoding p53 phosphoprotein, originally believed to be an oncogene, recently has been proposed as a candidate antioncogene (tumor-suppressor gene). Abnormalities of the p53 gene expression have been demonstrated in different human malignancies including carcinomas and sarcomas, but little information concerning p53 immunoreactivity in human lymphomas is so far available. In this study immunohistochemical staining for p53-protein was performed on frozen- and paraffin-embedded samples from patients with Hodgkin's (HD) and non-Hodgkin's lymphomas (NHL). No p53 immunoreactivity could be demonstrated in any cell type in nonneoplastic lymphoid samples, including germinal center cells in reactive lymph nodes and cortical thymocytes. On the other hand, a significant proportion of p53+ neoplastic cells was observed in 23 of 31 cases of HD and 17 of 68 cases of NHL. All positive lymphoma cases were diagnosed as high-grade or CD30+ anaplastic NHL. The demonstration of abnormal expression of p53 protein in these diseases can contribute to addressing unresolved issues regarding the origin and pathogenesis of HD and CD30+ anaplastic lymphomas.