Decreased in situ insulin receptor dephosphorylation in hyperglycemia-induced insulin resistance in rat adipocytes

The regulation of insulin receptor (IR) tyrosine (tyr) phosphorylation is a key step in the control of insulin signaling. Augmented IR tyr dephosphorylation by protein tyrosine phosphatases (PTPs) may contribute to insulin resistance. To investigate this possibility in hyperglycemia-induced insulin resistance, primary cultured rat adipocytes were rendered insulin-resistant by chronic exposure (18 h) to 15 mmo/l glucose combined with 10(-7) mol/l insulin. Insulin-resistant adipocytes showed a decrease in insulin sensitivity and a maximum response of 2-deoxyglucose uptake, which was associated with a decrease in maximum insulin-stimulated IR tyr phosphorylation in situ. To assess tyr dephosphorylation, IRs of insulin-stimulated permeabilized adipocytes were labeled with [gamma-32P]ATP and chased for 2 min with unlabeled ATP in the presence of EDTA. In a nonradioactive protocol, insulin-stimulated adipocytes were permeabilized and exposed to EDTA and erbstatin for 2 min, and IRs were immunoblotted with anti-phosphotyrosine (pY) antibodies. Both methods showed a similar diminished extent of IR tyr dephosphorylation in resistant cells. Immunoblotting of four candidate IR-PTPs demonstrated no change in PTP1B or the SH2 domain containing phosphatase-2 (SHP-2), whereas a significant decrease in leukocyte antigen-related phosphatase (LAR) (51 +/- 3% of control) and an increase in PTP-alpha (165 +/- 16%) were found. Activity of immunoprecipitated PTPs toward a triple tyr phosphorylated IR peptide revealed a correlation with protein content for PTP1B, SHP-2, and LAR but a decrease in apparent specific activity of PTP-alpha. The data indicate that decreased IR tyr phosphorylation in hyperglycemia-induced insulin resistance is not due to enhanced dephosphorylation. The diminished IR tyr dephosphorylation observed in this model is associated with decreased LAR protein content and activity.

Pathologic diagnosis of acute lymphocytic leukemia

With present knowledge, the optimal management of individual patients with acute leukemia requires that every case be studied by morphology, cytochemistry, cytogenetic, immunologic and molecular techniques. An algorithm for diagnostic evaluation and classification of ALL is provided in Fig. 11. Other techniques, such as DNA or cDNA [figure: see text] microarray, are at present important research tools but have not yet had a major effect on patient care. More detailed studies of individual patients need to be conducted at specialized cancer centers, where preservation of cells, DNA, RNA, or protein is possible. Such investigations will yield important information on the clinical importance of the expression of various markers, the prevalence and relevance of bilineage and biphenotypic leukemias, and above all will reveal the mechanisms of leukemogenesis and of disease evolution. Such insights will further aid clinicians in treating ALL and in preventing refractory disease.

Pathologic diagnosis of mantle cell lymphoma

Mantle cell lymphoma (MCL) is a clinicopathologic entity with distinctive morphologic and immunophenotypic features and a characteristic cytogenetic abnormality, the t(11;14)(q13;q32). Although MCL was recognized over 30 years ago, a lack of consensus regarding its morphologic features precluded its inclusion into non-Hodgkin's lymphoma (NHL) classification schemes until relatively recently. An accurate diagnosis of MCL is of great importance, since this tumor generally carries a poor prognosis and requires more aggressive and novel treatment regimens. In this article, we briefly overview the clinical features of MCL and then focus on the pathologic diagnosis of MCL, emphasizing morphologic findings and various ancillary techniques useful in the diagnostic workup. Involvement of lymph nodes and other sites, such as the spleen, liver, gastrointestinal tract, Waldeyer's ring, bone marrow, peripheral blood, and cerebrospinal fluid are reviewed. The diagnosis of high-grade variants of MCL is a particular challenge, as these tumors exhibit a broad spectrum of morphologic findings that can be misinterpreted as other types of NHL. The molecular basis of MCL is also briefly reviewed to highlight the biologic role of the t(11;14) and cyclin D1 overexpression in this tumor and the value of immunophenotypic and molecular methods for their detection as diagnostic aids.

Anaplastic large cell lymphomas presented as bone lesions: a clinicopathologic study of six cases and review of the literature

Non-Hodgkin's lymphomas uncommonly present as bone lesions. Most of these tumors are diffuse large B-cell lymphomas. Anaplastic large cell lymphoma (ALCL) presented as bone lesions is exceedingly rare. In this study, we describe six cases of ALCL that presented as solitary or multiple bone lesions. The average patient age was 33 years (range, 4 to 63 years) and the male to female ratio was 2:1. Fever and localized bone pain were the most frequent presenting symptoms. Radiologic examinations revealed osteolytic lesions in all cases, with three (50%) being multiple lesions and five (83%) involving the axial bones. All patients were initially assessed to have only bone involvement. Staging studies revealed mild cervical lymphadenopathy in one patient and no evidence of extraskeletal disease in the other five patients. Histologically, there was diffuse infiltration of one or more bones by large pleomorphic lymphoma cells. Immunohistochemical studies showed all six neoplasms were positive for CD30, EMA, and granzyme B. One case was of T-cell lineage, positive for CD3. One case was positive for the T-cell-associated antigen CD4. The remaining four cases were of null-cell type. In-situ hybridization for EBV was performed in five cases; all were negative. Despite the relatively low International Prognostic Index (IPI) of these patients (mean, 1.67; range, 1 to 3), the overall prognosis was relatively poor: three of six died of disease within 2 years of diagnosis, and two of six were alive with evidence of disease (follow-up, 6 mo to 2 years). Thus, compared to their nodal counterparts, ALCLs that present as bone lesions are distinguished by their uniform expression of EMA and granzyme B, and a relatively poor clinical outcome. Our results also suggest that ALK-1 expression in this clinical setting is not a favorable prognostic indicator.

Glandular malignant peripheral nerve sheath tumor: an unusual case showing histologically malignant glands

In this report, we describe a highly unusual case of glandular malignant peripheral nerve sheath tumor presenting as a neck mass in a previously healthy 29-year-old man. Grossly, the tumor was found to arise from a swollen peripheral nerve trunk. The tumor was largely composed of spindle cells that demonstrated marked nuclear pleomorphism and numerous abnormal mitotic figures. In addition, histologically malignant glandular structures lined by simple nonciliated columnar cells with goblet cells were found clustered in the center of the tumor. Examination of the swollen peripheral nerve trunk revealed the presence of a plexiform neurofibroma. The spindle cells were positive for S100. The glands were negative for S100 but positive for keratin, epithelial membrane antigen, and neuroendocrine markers (somatostatin, chromogranin, Leu-7, and calcitonin). This patient was subsequently diagnosed as having von Recklinghausen disease and died of tumor metastasis to the lungs 34 months after the presentation. To our knowledge, only 3 similar cases have been previously described in the literature.

Flow cytometric detection of CD79a expression in T-cell acute lymphoblastic leukemias

We evaluated the lineage specificity of CD79a in acute leukemias using 3-color flow cytometry in 58 consecutive cases. A panel of cell-surface antigens, including myeloid-associated markers, B-cell-associated markers, and T-cell-associated markers, was used. All cases of acute myeloid leukemia were CD79a-, whereas all cases of B-lineage acute lymphoblastic leukemia (ALL) were CD79a+. Three of 8 cases of T-cell ALL showed variable CD79a expression, indicating the presence of a blast subset expressing a relatively high level of CD79a. We investigated the clinical and pathologic characteristics of these 3 cases. All 3 cases had L1 or L2 morphology and expressed surface CD3. None of the other B-cell-associated markers were positive, although 1 case expressed CD13 and CD33. Uncommon random karyotypic abnormalities were identified in all 3 cases. Molecular studies demonstrated monoclonal gene rearrangement of T-cell receptor gamma in 2 of 3 cases. All 3 patients were 18 years old or younger; 1 patient did not enter remission, and 1 had disease relapse in 8 months. Our findings provide further support for the existence of a subset of T-cell ALL coexpressing CD3 and CD79a. Further study of the clinical and biologic significance of this subset may be warranted.

Coexisting thymic and gastric lymphomas of mucosa-associated lymphoid tissues in a patient with Sjögren syndrome

Lymphomas of mucosa-associated lymphoid tissues (MALTomas) arising from the thymus are extremely rare. In this case report, we describe a 36-year-old woman with an 11-year history of Sjögren syndrome who was found to have a thymic MALToma coexisting with a gastric MALToma. Both tumors shared similar histologic features, showing clusters of centrocytic-like B cells, lymphoepithelial lesions, and prominent plasmacytic differentiation. They also showed the following identical immunohistochemical features: CD20(+), IgA/lambda(+), CD5(-), and CD43(-). Molecular studies using polymerase chain reaction methods revealed monoclonal gene rearrangement of the immunoglobulin heavy chain in the gastric MALToma, but not in the thymic MALToma. The possible pathogenesis of this unusual case is discussed.

[Subcutaneous panniculitis-like T-cell lymphoma: expression of cytotoxic-granule-associated protein TIA-1 and its relation with Epstein-Barr virus infection]

OBJECTIVE

To study the clinicopathologic features, the expression of cytotoxic-granule-associated protein TIA-1 and Epstein-Barr virus (EBV) infection in subcutaneous panniculitis-like T-cell lymphoma (SPTCL).

METHODS

Totally 17 cases of SPTCL were studied. Immunohistochemical staining was done for TIA-1, CD45RO, CD3, CD20 and CD68, and in situ hybridization for EBV encoded small nuclear RNA (EBER1/2).

RESULTS

In the 17 cases of SPTCL, the ratio of male-to-female was 1:1.1 and the median age was 24 years old. The main clinical manifestations were asymptomatic plaques, nodules and masses. Histologically, the pattern of lymphoid cells infiltration was panniculitis. The infiltrated lymphoid cells were pleomorphic and their mitotic figures were few (0 - 2/hpt). In the tumor tissue, there might be epithilioid granulomas, multinuclear cells, beanbag cells, small pieces of necrosis and small vessels with lymphoid cells infiltration in the vascular wall. Immunohistochemically, all the cases showed a T-cell phenotype and the expression rate of TIA-1 was 100% (16/16). By in situ hybridization, the positive rate of EBV-EBER1/2 was 29.4% (5/17).

CONCLUSIONS

SPTCL has a specific histopathologic picture. It may originate from cytotoxic T lymphocytes or NK cells. Some of them may be accompanying with EBV latent infection.

Hepatosplenic T-cell lymphoma of alphabeta lineage in a 16-year-old boy presenting with hemolytic anemia and thrombocytopenia

The authors report an unusual case of peripheral T-cell lymphoma in a 16-year-old boy who presented initially with jaundice, splenomegaly, anemia, and thrombocytopenia. A lymphoma was found subsequently in the spleen, which was infiltrated extensively in the red pulp by medium-sized, blastic-appearing lymphoma cells. Immunologic characterization of these cells revealed positivity for CD3, CD5, CD45RO, CD56, and T-cell intracellular antigen (TIA), and negativity for CD2, CD3, CD4, CD8, CD57, CD34, and terminal deoxynucleotidyl transferase (TdT). Conventional cytogenetic studies revealed the presence of isochromosome 7q. On follow up, this patient deteriorated rapidly, with evidence of liver and bone marrow involvement. Although the overall clinical and pathologic features of this disease were characteristic of hepatosplenic gammadelta T-cell lymphoma, the T-cell receptor of this tumor showed an immunophenotype of alphabeta not gammadelta lineage. Using the Southern blot technique, the authors demonstrated monoclonal gene rearrangement of the T-cell receptor beta-chain. Thus, they confirmed the existence of hepatosplenic alphabeta T-cell lymphoma. In view of its overall similarity to hepatosplenic gammadelta T-cell lymphoma, this unusual entity probably represents a slight biologic variation of the same disease.

Sinusoidal CD30-positive large B-cell lymphoma: a morphologic mimic of anaplastic large cell lymphoma

Anaplastic large cell lymphoma (ALCL) has been recognized recently as a distinct clinicopathologic entity, restricted to a subset of CD30-positive diffuse large cell lymphomas of T/null lineage. Some of the characteristic features of ALCL, such as CD30 antigen expression and the presence of large pleomorphic lymphoid cells infiltrating lymph node sinuses, can be found rarely in diffuse large B-cell lymphomas. We collected 11 such cases, and their clinical, morphologic, and immunophenotypic features are reviewed. The age of the patients ranged from 36 to 82 years (mean, 63.2 years) with a male to female ratio of 1:1.2. All neoplasms were nodal with a sinusoidal infiltrative pattern, although four neoplasms also had foci of confluent growth. Eight tumors were composed predominantly of large pleomorphic cells with occasional Reed-Sternberg-like cells. The other three tumors had a higher proportion of large monomorphic lymphoid cells. Necrosis and admixed granulocytes were other common features. Immunophenotypically, all cases were positive for CD30 and CD20 or CD79a. All eight cases examined for anaplastic lymphoma kinase-1 immunoreactivity were negative. In situ hybridization for Epstein-Barr virus RNA was performed in eight cases; two were positive. Excluding one consultation case with no available clinical follow-up data, six patients died of the disease within 3 years and one had disease relapse within 1 year. We conclude that an unusual variant of diffuse large B-cell lymphoma can closely mimic ALCL. However, these neoplasms can be distinguished from ALCL by virtue of their B-lineage and lack of anaplastic lymphoma kinase-1 expression. Evidence of Epstein-Barr virus infection can be found in a small subset of these neoplasms.

The use of archival bone marrow specimens in detecting B-cell non-Hodgkin's lymphomas using polymerase chain reaction methods

The detection of B-cell non-Hodgkin's lymphoma (B-NHL) involving the bone marrow (BM) can be enhanced by assessing immunoglobulin heavy chain (IgH/JH) gene rearrangement using PCR. While the fresh BM aspirate has been the most commonly used specimen, the utility of archival BM tissues has not been extensively evaluated. We studied the BM from 13 patients with nodal B-NHL (7 low-grade and 6 intermediate grade), which were categorized into three groups based on the histologic finding of lymphoma (H) and the presence of a monoclonal IgH/JH band by PCR using fresh BM aspirates (M): (1) H(+)/M(+), 4 cases; (2) H(+)/M(-), 4 cases; and (3) H(equivocal)/M(-), 5 cases. Archival tissues available for study included paraffin-embedded trephine biopsy (TB)/aspirate clots (AC) and air-dried aspirate smears (AS). All TB (13/13) and a subset of AC (5/13) were B5-fixed, and all these tissues failed to yield analyzable DNA. In contrast, sufficient DNA was consistently obtained in AC that were formalin-fixed (8/13). Of these 8 cases, 2/3 of group 1, 3/3 of group 2, and 0/2 of group 3 had a monoclonal IgH band. Using DNA extracted from microdissected lymphoid aggregates morphologically evident in the AC sections, additional positive cases were identified: 1/3 of group 1 and 2/2 of group 3. In those 5 cases that did not have formalin-fixed TB/AC, sufficient DNA was extracted from AS in all cases; one additional positive case was identified in group 1. Overall, 4/4 (100%) of group 1, 3/4 (75%) of group 2, and 2/5 (40%) of group 3 showed molecular evidence of lymphoma. To conclude, archival BM specimens are a useful source of DNA for molecular detection of B-NHL involvement, and formalin appears to be a better fixative than B5. The use of these samples may improve the overall detection sensitivity.

CD44s as a surrogate marker for distinguishing intraductal papilloma from papillary carcinoma of the breast

BACKGROUND

It has been shown that CD44 variants are differentially expressed in normal and neoplastic breast tissues. The diagnostic value of these markers in distinguishing benign from malignant breast lesions has not been well examined.

AIMS

To evaluate the diagnostic value of CD44s in distinguishing between intraductal papillomas and papillary carcinomas of the breast, which may be difficult morphologically.

METHODS

Expression of CD44s detected by immunohistochemistry was studied in a series of intraductal papillomas (11) and papillary carcinomas (10). The normal breast tissues surrounding the lesions of these cases served as a control. The number of CD44s positive epithelial cells was scored and categorised as < 10%, 10-70%, or > 70%.

RESULTS

Normal breast epithelial cells and all intraductal papillomas (11 of 11) expressed CD44s in a high proportion of cells (> 70%). In contrast, the majority of papillary carcinoma cases (eight of 10) expressed this marker in < 10% of the cells. In the remaining two papillary carcinoma cases, positivity was seen in more than 10% but still less than 70% of the cells.

CONCLUSIONS

CD44s detection by immunohistochemistry is useful in distinguishing intraductal papillomas from papillary carcinomas of the breast.

[Fertilization in vitro and microinsemination. 6 years of experience in the Ospedale Microcitemico of Cagliari]

BACKGROUND

In this study the results of six years experience (1993-1998) in IVF, ICSI and assisted hatching on 442 sterile couples for a total of 868 cycles are reported. Since 1997 ICSI has also been carried out in cases of azoospermia extracting mobile spermatozoa from the epididymal (MESA) or from the testicle (TESE).

METHODS

Ages ranged from 20 to 48 and mean years sterility was 5.868 cycles were carried out of which 153 (17.62%) were for IVF, 705 (81.22%) for ICSI and 10 (1.15%) for MESA and TESE. Assisted hatching was performed through "partial zona dissection" in 329 cases on a total of 987 embryos.

RESULTS

The pregnancy rates per embryo transfer in IVF and ICSI cycles were 22.4 and 19.96% respectively. Results considering patients age were: 33.87% below 35, 29.55% between 35 and 38 and 6.60% above 38. In the group of 189 assisted hatching patients the evolutive pregnancy rate rose from 15.78 to 26.40% and multiple pregnancies from 28.63 to 42%.

CONCLUSIONS

ICSI has offered high rates of fertilization and pregnancy even in extreme cases of oligoasthenospermia or cases of azoospermia adopting MESA or TESE techniques. A decisive factor on pregnancy rates is age, very low over 38 years. Assisted Hatching further increased the pregnancy rates.

Cyclin D1 overexpression in Spitz nevi: an immunohistochemical study

The morphologic distinction between Spitz nevus and malignant melanoma can be difficult. Because cyclin D1 has been reported to be overexpressed in malignant melanomas, but not in common acquired nevi, we hypothesized that cyclin D1 might be a useful marker to distinguish Spitz nevi from malignant melanoma. Thus, we assessed for cyclin D1 expression in 11 Spitz nevi (10 compound and 1 intradermal) and 9 malignant melanomas (4 Clark stages I-III and 5 Clark stages IV-V) using an immunohistochemical method and routinely fixed and processed tissues. The cyclin D1 results were arbitrarily divided into three groups: 0% to 10%, >10% to 25%, and >25%. We confirmed the observations reported previously by others that cyclin D1 is expressed in malignant melanomas but not in common acquired nevi. Unexpectedly, a relatively high number of cyclin D1-positive cells (i.e., >10%) was also found in all cases of Spitz nevus. However, unlike malignant melanoma, the cyclin D1 positivity in Spitz nevi was present in a zonal pattern. In other words, the number of cyclin D1-positive cells decreased as the lesion extended more deeply, with the number of positive cells in the reticular dermis being less than that in the papillary dermis. Fluorescence in situ hybridization methods were used to assess amplification of 11q13, the locus harboring the cyclin D1 gene, in four cases of Spitz nevus; all were disomic. Using the antibody MIB-1, we compared cyclin D1 expression to the proliferation rate in Spitz nevi. Despite the high cyclin D1 positivity, all Spitz nevi had a relatively low number of MIB-1-positive cells (mean=3.2%), which was significantly lower than that of malignant melanomas (mean=15.3%) (p < 0.001). Thus, unlike malignant melanoma, there appears to be a dissociation between cyclin D1 overexpression and cell proliferation in Spitz nevi.

Frequency of CD43 expression in non-Hodgkin lymphoma. A survey of 742 cases and further characterization of rare CD43+ follicular lymphomas

CD43 expression on B cells is an immunophenotypic feature suggestive of malignancy. In the light of its diagnostic importance, we performed a comprehensive survey of CD43 expression in various types of non-Hodgkin lymphoma (NHL) and determined the frequency of its expression in routinely fixed paraffin-embedded tissues. Tissue sections in 742 cases of NHL, pretreated by the heat-induced epitope retrieval technique, were immunostained using an anti-CD43 antibody. Three categories of CD43 positivity were found: (1) more than 90% of T-cell lymphoma, mantle cell lymphoma, B-cell small lymphocytic lymphoma, and Burkitt lymphoma cases were positive; (2) 20% to 40% of nodal and extranodal marginal zone lymphoma (MZL), diffuse large B-cell lymphoma, Burkitt-like B-cell lymphoma, and lymphoplasmacytoid lymphoma cases were positive; and (3) 0% to 6% of primary splenic MZL and various types of follicular lymphoma cases were positive. Most CD43+ follicular lymphomas were predominantly large cell type with focally diffuse areas; their follicular center cell origin in 4 of 8 cases was supported by the presence of CD10 immunoreactivity and/or t(14;18) fusion gene product. CD43 is frequently detectable in a subset of B-NHL, and, thus, it seems to be a highly sensitive marker for these tumors. CD43 also may be a useful marker for classifying B-cell NHLs by virtue of its differential expression in these tumors.

Untreated chronic lymphocytic leukemia concurrent with or followed by acute myelogenous leukemia or myelodysplastic syndrome. A report of five cases and review of the literature

Although it has been known that patients with chronic lymphocytic leukemia (CLL) have a higher frequency of second malignant neoplasms, the development of acute myelogenous leukemia (AML) or myelodysplastic syndrome (MDS) in these patients is extremely rare. Most reported cases have been therapy-related. In this article, we report the clinical and immunophenotypic features of 5 cases of untreated CLL concurrent with or followed by the development of AML or MDS. All 5 patients were men, with ages ranging from 57 to 87 years (mean, 73.8 years). Four patients had AML and 1 patient had refractory anemia with ringed sideroblasts. In the 4 cases of AML and CLL, 2 distinct cell populations (i.e., myeloblasts and lymphocytes) were identified morphologically and/or immunophenotypically. Our findings support that this rare concurrence of AML or MDS and untreated CLL may represent 2 separate disease processes.

Differential expression of cyclin D1 in breast papillary carcinomas and benign papillomas: an immunohistochemical study

OBJECTIVES

Distinguishing intraductal papilloma from papillary carcinoma of the breast can be difficult using histologic criteria. Since cyclin D1, a G1 cell-cycle regulatory protein, is detectable immunohistochemically in a subset of breast carcinomas but not in benign breast tissues, we hypothesized that cyclin D1 immunoreactivity may be a marker for identifying papillary carcinoma.

METHODS

Using an immunohistochemical method, we assessed for cyclin D1 expression in 8 breast papillomas and 6 papillary carcinomas, all of which were formalin fixed, routinely processed, and paraffin embedded. Cyclin D1 positivity also was compared with the overall proliferation rate, which was assessed by using the proliferation marker Ki-67. In each case, a 200-cell count was performed to obtain the percentage of cells positive for these 2 markers.

RESULTS

The percentage of cyclin D1-positive cells was significantly higher in papillary carcinomas (89%+/-18%; range, 53%-98%) than in papillomas (8%+/-7%; range, 0%-19%). This difference was highly statistically significant (P < .0001). Although the difference in Ki-67 positivity between these 2 groups was also statistically significant (P = .01), separation of papillary carcinomas and papillomas by Ki-67 immunoreactivity was less clear because of overlapping values between groups: 13% +/-6%; range, 9% to 23% for papillary carcinomas versus 8%+/-2%; range, 6% to 12% for papillomas.

CONCLUSIONS

These results support the notion that cyclin D1 is a useful marker for distinguishing breast papillomas from papillary carcinomas. The marker Ki-67 is also helpful, but is less useful than cyclin D1, owing to the overlap in Ki-67 results in papillomas and papillary carcinomas.

Contributions of the entorhinal cortex, amygdala and hippocampus to human memory

Recent studies have indicated that, in the monkey, the rhinal cortex (consisting of the entorhinal and perirhinal cortices) is more important to visual recognition memory than the hippocampus or amygdala. The present study investigated the role of the entorhinal cortex in humans using memory scores from surgical epilepsy patients classified according to their mesial temporal lobe pathology. The temporal lobe removals included 4-5 cm of neocortex, amygdala, rhinal cortex and 2-3 cm of the hippocampus and parahippocampal gyrus. Compared to autopsied control subjects, all of the patients showed significant gliosis in the amygdala, but they differed as to whether or not there were entorhinal and/or hippocampal abnormalities. Both preoperatively and one or more years postoperatively, the patients performed tests of verbal recall (Wechsler Memory Scale Logical Memory), visual recall (Rey Figure), verbal recognition and visual recognition (Warrington Recognition Memory Test: Words and Faces, respectively). Preoperatively, patients with hippocampal pathology showed deficits in visual recall. Postoperatively, a significant drop in verbal and visual recall was seen only for patients who lost intact hippocampal tissue, irrespective of the condition of the excised entorhinal cortex. Together, the results argue that the hippocampus is more important than the entorhinal cortex for the recall of newly learned information.

Frequency of bcl-2 expression in non-Hodgkin's lymphoma: a study of 778 cases with comparison of marginal zone lymphoma and monocytoid B-cell hyperplasia

The oncoprotein, bcl-2, is expressed in various types of non-Hodgkin's lymphoma (NHL). Immunodetection of this protein is a useful method for distinguishing follicular hyperplasia from follicular lymphoma. Although bcl-2 might also be a useful marker for distinguishing reactive monocytoid B-cell hyperplasia from its putative malignant counterpart, marginal zone lymphoma, there were no extensive studies to date that tested this. Therefore, we performed a survey of bcl-2 expression in 778 cases of NHL using immunohistochemical techniques applied to routinely processed and paraffin-embedded tissues. Of 20 reactive monocytoid B-cell hyperplasias, none were bcl-2 positive, compared with 118 (79%) of 150 marginal zone lymphomas (P = .001). With respect to the follicular lymphomas in our study, of the 110 Grade I lymphomas, 107 (97%) were bcl-2 positive, 119 (83%) of the 143 Grade II lymphomas were positive, and 71 (74%) of the 96 Grade III lymphomas were positive. The bcl-2 positivity of Burkitt-like high-grade B-cell lymphoma was significantly different from that of Burkitt's lymphoma (4 [67%] of 6 vs. 0 of 5; P = .02). T-cell NHL had a significantly lower bcl-2 positivity than did B-cell NHL (10 [45%] of 22 vs. 627 [83%] of 756; P = .0001). Therefore, bcl-2 is a highly sensitive marker for follicular lymphoma and a useful marker for distinguishing reactive monocytoid B-cell hyperplasia from marginal zone lymphoma The significant difference in bcl-2 positivity between Burkitt-like high-grade B-cell lymphoma and Burkitt's lymphoma suggests an additional diagnostic use for this protein.

Expression of the cell-cycle-related proteins E2F-1, p53, mdm-2, p21waf-1, and Ki-67 in multiple myeloma: correlation with cyclin-D1 immunoreactivity

Approximately 30% of multiple myelomas (MMs) express cyclin D1 when assessed using immunohistochemical techniques. Cyclin D1 expression correlates with greater tumor burden in MM, because cyclin D1-positive cases are more frequently associated with extensive bone marrow involvement, i.e., high pathologic stage, than are cyclin D1-negative cases. The mechanisms that explain this association are unknown. To explore other differences between cyclin D1-positive and cyclin D1-negative MMs, we assessed 59 MMs immunohistochemically for several G1 cell-cycle regulatory proteins, including cyclin D1, E2F-1, p53, mdm-2, and p21waf-1, using routinely fixed and processed, paraffin-embedded bone marrow specimens. Twenty MMs (34%) were cyclin D1 positive, and 39 (66%) were cyclin D1 negative. Eighteen (90%) of 20 cyclin D1-positive MMs were Stage III, in contrast to 19 (49%) of 39 cyclin D1-negative MMs (P = .003). Cyclin D1-positive MMs were more likely to express E2F-1 (16/20 vs. 4/39, P < .001), p53 (11/20 vs. 10/39, P = .041), and p21waf-1 (12/20 vs. 7/39, P = .003). There was no significant difference in mdm-2 expression between these groups. We also assessed proliferation rate using an antibody specific for the Ki-67 antigen. A relatively high percentage (> 20%) of Ki-67-positive cells was found in cyclin D1-positive MMs compared with cyclin D1-negative MMs (13/20 vs. 3/39, P < 0.001). These results suggest that cyclin D1-positive MMs are more likely to possess additional derangements involving other G1 cell-cycle regulatory proteins. We speculate that these abnormalities might result in increased proliferation, thereby explaining the correlation between cyclin D1 expression and greater tumor burden.

Immunohistochemical detection of E2F-1 in non-Hodgkin's lymphomas: a survey of 124 cases

E2F-1 is a transcription factor that mediates cell cycle progression from the G1 to S phase and is normally regulated by a group of proteins, including cyclin D1. Although deregulation of E2F-1 is implicated in neoplastic transformation, in situ examination of this protein has not been performed to date. Using an immunohistochemical technique applied to routinely fixed, paraffin-embedded tissue sections, we evaluated E2F-1 expression in reactive lymphoid tissues and in 124 cases of non-Hodgkin's lymphoma (NHL) of various types. In reactive lymphoid tissues, E2F-1 was expressed predominantly by large noncleaved cells in germinal centers and by a small subset of cortical thymocytes. Mantle zones and splenic marginal zones were negative. Among the NHLs, four types had a relatively high percentage (> 20%) of E2F-1-positive cells: mantle cell lymphoma (19 of 19), lymphoblastic lymphoma (5 of 5), small noncleaved cell lymphoma (4 of 6), and hepatosplenic gammadelta T-cell lymphoma (3 of 3). The consistent detection of many E2F-1-positive cells in mantle cell lymphoma is in contrast to other small B-cell NHLs (n = 29), which had relatively few (< 10%) E2F-1-positive cells. This finding suggests that immunohistochemical staining for E2F-1 as a supplement to the existing markers, such as cyclin D1, might be useful in the differential diagnosis of NHLs composed of small B cells.