Fine structure of the exoerythrocytic stage of Plasmodium cynomolgi.

The light microscopy of primate exoerythrocytic stages (liver stage) of malaria is well described. This report demonstrates the ultrastructure of the 7-day exoerythrocytic stage of Plasmodium cynomolgi in the liver of a rhesus monkey.

Pitting function of the spleen in malaria: ultrastructural observations.

Ultrastructural studies of spleens from monkeys infected with Plasmodium knowlesi suggest that the spleen removes or "pits" malaria parasites from red cells. This function may explain the presence of nonparasitized spherocytic erythrocytes in the peripheral blood and may in part account for the discrepancy between the excessive hemolysis and the number of parasitized erythrocytes in animals with experimentally induced malaria.

Erythrocytes: pits and vacuoles as seen with transmission and scanning electron microscopy.

Vacuoles containing inclusions were observed by transmission electron microscopy in erythrocytes of a splenectomized patient with hemoglobin Ann Arbor. The membranes of these vacuoles became fused with the surface membrane of the red cell, thus opening the vacuoles and exposing their contents to the outside. These vacuoles when they have become thus attached to the cell membrane of the erythrocyte are responsible for the pits observed with scanning electron microscopy.

Simultaneous lymphocyte predominant Hodgkin's disease and large-cell lymphoma.

Lymphocyte-predominant Hodgkin's disease (LPHD) is a subtype of Hodgkin's disease characterized by an indolent clinical course and by distinctive histological and immunological features. Coexistence of diffuse or nodular LPHD with large-cell non-Hodgkin's lymphoma (NHL) distant from the presenting site has rarely been reported. We studied three cases of simultaneous LPHD and large-cell NHL. Two cases involved men, aged 66 and 20 years, with neck and axillary masses, respectively. Biopsy of each mass revealed nodular LPHD. In one case the spleen contained areas of both LPHD and large-cell NHL, whereas only large-cell NHL was found in the spleen of the other patient. The patients are alive 49 months and 29 months after diagnosis. The third case was from a 4-year-old boy with a neck mass that revealed both diffuse LPHD and areas of large-cell NHL. Local recurrence prompted therapy, and the boy is in complete remission 31 months after diagnosis. Immunophenotyping in all three cases showed the Reed-Sternberg variant lymphocytic and histiocytic cells to be B-lymphocytes. The NHL cells in two cases were B-cells; in the child, the cells reacted only with leukocyte common antigen. Immunoglobulin heavy- and light-chain genes were rearranged in the NHL cells in the spleen of one case, and heavy-chain genes were rearranged in the lymph node of the child. It appears that when large-cell NHL and LPHD occur simultaneously, even when the large-cell NHL occurs at a site distant from the LPHD, the patient's clinical course is like the indolent course of LPHD rather than like the typically aggressive course of large-cell NHL. This clinical course, together with immunophenotyping and genotyping studies, suggests a developmental relationship between these two lymphomas when they occur simultaneously.

A multilobular variant of hairy cell leukemia with morphologic similarities to T-cell lymphoma.

Hairy cell leukemia is a distinct chronic lymphoproliferative disorder composed of morphologically unique B-lymphocytes. The diagnosis of hairy cell leukemia is usually based on the morphology of blood/bone marrow aspirate smears and bone marrow sections. We report three cases of hairy cell leukemia that had an unusual multilobated nuclear appearance seen on both smears and tissue sections. Many of the hairy cells exhibited marked nuclear lobulations and convolutions, giving rise to clover leaf-like nuclear configurations. The nuclear chromatin was finely reticular and characteristic of hairy cell leukemia. Bone marrow sections were hypercellular and the leukemic infiltrate was loosely distributed. A leukemic infiltrate was also seen in splenic sections in two cases in which splenectomy was carried out. Tartrate-resistant acid phosphatase cytochemistry was positive in all three cases. Flow cytometric analysis and paraffin section immunoperoxidase studies confirmed the B-cell lineage of the leukemic cells in all cases. The multilobulated nuclei described in these three cases are quite unusual in hairy cell leukemia; they could potentially lead to an erroneous diagnosis of T-cell lymphoma or leukemia. Features typical of hairy cell leukemia, such as the nuclear chromatin distribution and pattern of bone marrow infiltration, together with the clinical history, are helpful in establishing a correct diagnosis of these variant cases of hairy cell leukemia.

Classification of primary gastric lymphomas according to histologic features.

Histologic features of low-grade gastric lymphomas of mucosa-associated lymphoid tissue (MALT) have been extensively described, and transformation to a large cell (high-grade) lymphoma can occur. We characterize high-grade gastric lymphoma histologically in an attempt to distinguish between MALT-type and non-MALT-type lesions. We studied a series of 60 gastric lymphomas and characterized them clinically, histopathologically, and immunophenotypically. Low-grade gastric lymphomas were classified according to established criteria. High-grade lymphomas were classified in three groups based on the presence or absence of a low-grade component and lymphoepithelial lesions (LELs): 1) high-grade MALT lymphomas appearing in low-grade MALT lymphomas (LG/HG MALT lymphoma); 2) large cell lymphoma with LELs composed of large cells (high-grade LELs) but without a low-grade component (HG MALT lymphoma); and 3) diffuse large cell lymphoma without a low-grade MALT lymphoma component or LELs (DLCL). Twenty-two lymphomas were classified as low-grade MALT lymphomas, 16 as LG/HG MALT lymphomas, 10 as HG MALT lymphomas, and 12 as DLCL. B-cell immunophenotype was confirmed in all 55 cases in which immunophenotyping was performed. Low-grade LELs were seen in all low-grade MALT lymphomas, and CD20(L26) expression confirmed B-cell phenotype in the LELs in 20 of 20 cases. Clinical follow-up was available for 56 patients (range, 1-264 months; mean, 57 months). Actuarial analysis of disease-specific survival and relapse-free survival showed that clinical stage was highly statistically significant (P < 0.0001), whereas histologic type and grade approached statistical significance. Multivariate analysis showed that clinical stage was the only significant factor in relapse-free and disease-specific survival.

Megakaryocytes in the giant platelet syndrome. A cytochemical and ultrastructural study.

When compared to normal megakaryocytes, those from a patient with the giant platelet syndrome exhibited numerous cytochemical abnormalities. These reflected disturbances in the metabolism of RNA, glycogen, arginine-rich histone, and various glycolytic enzymes. Ultrastructural studies of the abnormal megakaryocytes also showed decreased glycogen and RNA (ribosomes) as well as aberrations of nuclear lobulation.

Primary T-cell lymphoma of the adrenal glands with adrenal insufficiency.

A 74-year-old man with bilateral adrenal gland masses presented with adrenal insufficiency. Biopsies and immunohistochemical staining of both masses revealed a large cell T-cell lymphoma. The lymphoma subsequently involved the central nervous system. A review of the literature disclosed that this is an extremely uncommon presentation of lymphoma.

Leu-M1-positive small cell carcinoma.

A case of metastatic small cell carcinoma of the lung is reported; initially, on the basis of morphology, phenotyping with monoclonal antibodies, and cytochemistry, the carcinoma was interpreted as a hematopoietic neoplasm. Noncohesive blast-like cells observed in bone marrow and lymph node biopsy specimens stained with the monoclonal antibodies Leu-M1 and OKIa1 and were also positive for nonspecific esterase and acid phosphatase. Although these findings suggested a monocytic origin for the neoplastic cells, further analysis, including ultrastructural examination, disclosed metastatic small cell carcinoma. This case illustrates the need for caution in the interpretation of staining with monoclonal antibodies because of the potentially wide range of normal and abnormal cells and tissues that may react with monoclonal reagents.

Anti-CD34 immunoperoxidase staining in paraffin sections of acute leukemia: comparison with flow cytometric immunophenotyping.

Anti-CD34 is a monoclonal antibody that reacts with bone marrow progenitor cells and leukemic blasts, and is expressed on 30% to 50% of all acute leukemias. Detection of CD34 has previously been restricted to flow cytometric studies. To expand the utility of CD34, we immunostained 46 paraffin-embedded bone marrow specimens with acute leukemia; results were compared with flow cytometric studies. CD34 reactivity was also evaluated in nine chronic leukemia cases, 27 malignant lymphoma cases (Hodgkin's disease and non-Hodgkin's lymphoma), six normal bone marrow specimens, and three benign, hyperplastic lymph node specimens. All cases that were CD34 positive by flow cytometry (11 of 19 B-cell precursor acute lymphoblastic leukemia cases, one of six T-cell acute lymphoblastic leukemia cases, and seven of 21 acute myeloblastic leukemia cases) were also CD34 positive in paraffin sections. Both cell membrane and cytoplasmic staining was seen. The positivity percentage and fluorescence intensity by flow cytometry correlated with the estimated number of stained cells and the intensity of immunoperoxidase staining in 18 of 19 CD34-positive cases. The remaining bone marrow and lymph node cases studied were CD34 negative; prominent endothelial cell staining, however, was noted. This is the first report of anti-CD34 staining of acute leukemia in paraffin-embedded sections. In contrast to other monoclonal antibodies reactive in bone marrow paraffin sections with leukemia, anti-CD34 immunoperoxidase staining is limited to leukemic blasts and may provide useful diagnostic information when flow cytometric studies are not available.

Site-dependent phenotypic heterogeneity in peripheral T-cell lymphoma.

Peripheral T-cell lymphomas constitute a heterogeneous population of postthymic T-cell malignancies. Characteristically, they present a varied phenotypic expression, which can be helpful in establishing the diagnosis. A case of a peripheral T-cell lymphoma in a 76-year-old man is described. The malignant cells in the skin and bone marrow were of the T4 (helper/inducer) phenotype, yet they did not express pan-T-cell antigens, such as T11, or functional E rosettes. In a biopsy specimen from a lymph node, however, the malignant cells had a helper/inducer phenotype and also expressed the pan-T-cell antigens T11 and Leu-5. Additionally, the malignant cells from the lymph node formed E rosettes. This study demonstrates the phenotypic heterogeneity of malignant T cells, which appears to be site-dependent.

Follicular lymphoma with involvement of the splenic marginal zone: a pitfall in the differential diagnosis of splenic marginal zone cell lymphoma.

Follicular lymphomas (FL) involving the spleen arise in and expand the germinal centers of the white pulp, whereas mantle cell lymphomas arise in the mantle zone and surround the benign germinal center. The recently described marginal zone cell lymphoma (MZCL) is a B-cell neoplasm characterized by concentric expansion of cells around the follicle, with or without infiltration of the mantle zone or germinal center. In addition, the immunoglobulin heavy chain gene is rearranged although none of the MZCL reported have been shown to be positive for the bcl-2 gene translocation by molecular studies. We report a patient with FL showing preferential involvement of the marginal zone of spleen morphologically mimicking a primary splenic MZCL. The patient reported here had a well-documented previous lymph node diagnosis of FL. The immunoglobulin heavy chain gene and bcl-2 gene rearrangement analysis confirmed the clonal origin of both the original FL, as well as the lymphoma, with a marginal zone pattern in the spleen.

Anti-CD10 immunoperoxidase staining of paraffin-embedded acute leukemias: comparison with flow cytometric immunophenotyping.

CD10 is common in B-precursor acute lymphoblastic leukemia (ALL) but is rare in acute myeloid leukemia (AML). However, until recently, analysis for CD10 has generally required fresh or frozen tissue. 56C6 is a monoclonal antibody that is now commercially available for the detection of CD10 in routinely processed paraffin-embedded tissue. Immunoperoxidase stains for CD10 on paraffin-embedded bone marrow core biopsy specimens (B5-fixed, decalcified) and marrow aspirate clots (formalin-fixed) were compared with flow cytometric immunophenotyping for CD10 on fresh cell suspensions in 20 cases of AML and in 30 cases of ALL. CD10 detection by immunohistochemistry agreed with CD10 by flow cytometry in 98% (49 of 50) of acute leukemias. The results matched in 100% (20 of 20) of AML. Five percent (1 of 20) of AMLs expressed CD10. Two of the AMLs with monocytoid differentiation were interpreted as negative for CD10 by flow cytometry, although these had nonspecific dim immunofluorescence for multiple markers, including CD10, and these cases were negative by immunohistochemistry. CD10 detection by immunohistochemistry agreed with CD10 by flow cytometry in 97% (29 of 30) of ALL. Eighty-four percent (21 of 25) of B-precursor ALL and 40% (2/5) of T-lineage ALL expressed CD10 by immunohistochemistry. In 1 case of B-precursor ALL, CD10 was dimly positive in 24% of the blasts by flow cytometry but negative by immunohistochemistry. We conclude that immunohistochemical staining of paraffin-embedded tissue, either B5- or formalin-fixed, is an effective method for the detection of CD10 in acute leukemia. This technique is useful in distinguishing AML from ALL.

Adhesion molecule expression in CD5-negative/CD10-negative chronic B-cell leukemias: comparison with non-Hodgkin's lymphomas and CD5-positive B-cell chronic lymphocytic leukemia.

The classification of CD5-negative/CD10-negative chronic B-cell leukemias (CD5-/CD10- CBL) can be problematic. Most of these cases may represent leukemic non-Hodgkin's lymphoma (NHL) other than B-cell chronic lymphocytic leukemia (BCLL); nonetheless, some investigators still advocate the term "CD5-negative BCLL." Because adhesion molecule (AdMol) expression patterns reflect the biology of lymphoid neoplasms, we studied a series of 106 B-cell lymphoproliferative disorders, including CD5+ BCLL (n = 56), NHL other than BCLL (n = 35), and CD5-/CD10- CBL (excluding hairy cell leukemia and prolymphocytic leukemia) with no prior history of NHL (n = 15) for expression of components of the very late antigen-4 complex (alpha4/beta1 integrin (CD49d/CD29)), components of the mucosal addressin-cell adhesion molecule receptor (alpha4(CD49d)/beta7 integrin), and L-selectin (CD62L). CD62L expression was significantly greater in CD5+ BCLL than in NHL (P < .001). Conversely, CD29, CD49d, and beta7-integrin expression were significantly greater in NHL than in CD5+ BCLL (P < .001 for each marker). These differences persisted when only blood and bone marrow samples were analyzed, with the exception of differences in CD62L expression, which approached, but did not reach, statistical significance (P = .08). The group of CD5-/CD10- CBL displayed an AdMol profile similar to NHL and was significantly different than CD5+ BCLL in expression of beta7 integrin, CD29, CD49d, and CD62L (P range < .001-.011). In summary, CD5-/CD10- CBL display an AdMol profile resembling NHL and significantly different from CD5+ BCLL, supporting the growing notion that "CD5-negative BCLL" generally represents leukemic NHL rather than a variant of true CD5+ BCLL.

Ki-1 anaplastic large cell lymphoma with a prominent leukemic phase.

Patients with Ki-1 (CD30)-positive anaplastic large cell lymphoma (ALCL) occasionally have rare circulating lymphoma cells. We report a case of ALCL with a prominent leukemic phase. A 36-year-old man presented with widespread ALCL involving lymph nodes, spleen, pleural fluid, cerebrospinal fluid, and bone marrow. His white blood cell count was 106,000/mm3 with 20% lymphoma cells. The circulating neoplastic cells were large, and had irregular nuclei with multiple small nucleoli, ample cytoplasm, and multiple clear cytoplasmic vacuoles. This case illustrates that ALCL may have a marked leukemic phase composed of large anaplastic cells.

Detection of immunoglobulin heavy chain gene rearrangement by polymerase chain reaction in chronic active gastritis associated with Helicobacter pylori.

Chronic active gastritis associated with Helicobacter pylori (CAG-Hp) has been linked to the pathogenesis of gastric B-cell lymphomas of mucosa-associated lymphoid tissue (MALT). To determine whether monoclonal lymphoid populations are present in CAG-Hp and histological predictors of monoclonality exist, the authors examined 46 endoscopic biopsies from 41 patients with CAG-Hp. The authors scored gastric biopsies for the presence of lymphoepithelial lesions (LELs), intensity of lymphoid infiltrate, presence of lymphoid aggregates and germinal centers, coexpression of CD43 (Leu 22) on B cells, and cytoplasmic immunoglobulin light chain restriction in formalin-fixed, paraffin embedded tissues. DNA extracts from these routinely processed tissues were analyzed for immunoglobulin heavy chain (IgH) gene rearrangement by polymerase chain reaction (PCR). Histological features, immunophenotype, gene rearrangement status, and clinical information were correlated. Six of the 46 biopsies (13%) from six of 41 patients (15%) showed a monoclonal PCR pattern. Monoclonal PCR patterns correlated with the presence of LELs (P<.015) but not with intensity of lymphoid infiltrate, presence of germinal centers, or presence of lymphoid aggregates. LELs correlated with germinal centers (P<.003) and intensity of infiltrate (P<.0001). None of the cases showed cytoplasmic light chain restriction nor coexpression of CD43 on B cells by immunohistochemistry. Clinical follow-up was available in all six patients whose gastric biopsies had a monoclonal PCR pattern (median, 58 months; range, 1 to 66 months) and 33 of the 35 patients with biopsies showing a polyclonal PCR pattern (median, 41 months; range 0.1 to 63 months). No patient developed gastric lymphoma. Monoclonality of lymphoid cells was detected by IgH PCR in 13% of patients with CAG-Hp. Although the authors cannot exclude the possibility that some patients with monoclonal gastric lymphoid infiltrates may eventually develop overt lymphoma, no histological, immunophenotypic, nor clinical evidence of lymphoma was noted at presentation or on clinical follow-up. Given the high incidence of CAG-Hp in the general population and the relatively low incidence of gastric MALT lymphoma, clinicopathologic correlation is needed when interpreting tests for clonality in this setting. The presence of clonal IgH gene rearrangement in CAG-Hp supports the hypothesis that H pylori is involved in the pathogenesis of low grade gastric B-cell MALT lymphomas.

Primary diagnosis of whipple disease manifesting as lymphadenopathy: use of polymerase chain reaction for detection of Tropheryma whippelii.

Whipple disease is a rare, chronic multisystem disease associated with the recently characterized organism Tropheryma whippelii. Extraintestinal manifestation involving the central nervous system, heart, and joints occasionally occurs. Involvement of the abdominal lymph nodes, especially the mesenteric and periaortic nodes, is not uncommon. However, peripheral lymphadenopathy as the sole clinical manifestation of Whipple disease is rare. We describe 2 patients with Whipple disease whose initial manifestation was lymphadenopathy. Lymph nodes from both patients showed infiltration of the sinuses by macrophages containing periodic acid-Schiff-positive, diastase-resistant, sickle-like structures. Electron microscopic evaluation confirmed the presence of rod-like organisms. DNA from each sample was amplified by the polymerase chain reaction using a specific set of oligonucleotide primers developed against the 16S ribosomal RNA coding sequence of T. whippelii. The histopathologic features and differential diagnosis of lipogranulomatous lymphadenopathy secondary to Whipple disease, as well as use of molecular-based assays, are discussed.

Coexistence of two lymphomas with distinctive histologic, ultrastructural, and immunologic features.

The unusual coexistence of two distinct lymphomas in 44-year-old woman is described. Nodular, poorly differentiated lymphocytic lymphoma and diffuse histiocytic lymphoma were present in separate sites and were readily distinguished both histologically and ultrastructurally. In addition, the lymphocytic lymphoma was shown to be derived from complement receptor B lymphocytes of follicular center cell type, whereas the histiocytic lymphoma cells were devoid of complement receptors, receptors for IgG (Fc receptors), and surface immunoglobulin. Despite intensive chemotherapy and radiation therapy, the patient died within eight months of the initial diagnosis. Although histiocytic lymphoma was widely disseminated at autopsy, lymphocytic lymphoma was not found. Presumably the histiocytic lymphoma was refractory to therapy, in contrast to the lymphocytic lymphoma, which was selectively eradicated.

Leukemic phase of mantle cell lymphoma, blastoid variant.

Six patients with mantle cell lymphoma, blastoid variant, involving the blood are described. The circulating blast-like cells suggested the possibility of acute leukemias, chronic lymphoproliferative disorders or peripheralized lymphomas. The WBC counts ranged from 3,700 to 249,000/microL (3.7-249.0 x 10(9)/L) and the absolute lymphocyte counts from 1,000 to more than 200,000/microL (1.0 to > 200.0 x 10(9)/L). The peripheral blood smears showed a spectrum of cells, from small mature lymphocytes with irregular nuclei to medium-sized lymphocytes with blast-like chromatin. However, the morphologic features in a lymph node biopsy specimen and the immunophenotype confirmed a diagnosis of mantle cell lymphoma, blastoid variant. By flow cytometry the lymphoma cells expressed B-cell-associated antigens (CD19, CD20 and CD22), coexpressed CD5, lacked CD23, and expressed moderate intensity monoclonal surface immunoglobulin and CD20. Cytogenetic analysis showed the characteristic t(11;14) in 2 of 4 analyzed specimens. Mantle cell lymphoma, blastoid variant, is part of the differential diagnosis for blast-like cells.

Precursor B lymphoblastic lymphoma presenting as lytic bone lesions.

Precursor B lymphoblastic lymphoma is an aggressive but potentially curable disease. This lymphoma most often manifests in the skin and lymph nodes and, less commonly, as lytic bone lesions. In the bone, this lymphoma must be differentiated from small round blue cell tumors, diffuse large B-cell lymphoma, and acute myelogenous leukemia. We describe the morphologic and immunophenotypic features in 4 patients, 2 children, 1 teenager, and 1 adult, who initially presented with bone pain and osteolytic lesions but without peripheral blood or iliac bone marrow involvement. Positive immunohistochemical staining of the neoplastic cells was observed for anti-CD10 (3/4), CD20 (3/4), CD34 (1/4), CD43 (4/4), CD45/CD45RB (2/4), CD79a (4/4), CD99 (MIC2) (2/4), and terminal deoxynucleotidyl transferase (4/4). CD3 was absent in all cases. Immunophenotyping these neoplasms is essential to establish the correct diagnosis of precursor B lymphoblastic lymphoma, and a panel of antibodies is required because of the immunophenotypic heterogeneity.