John G. Strickler

Splenic Vascular Tumors: A Histologic, Immunophenotypic, and Virologic Study

Vascular tumors of the spleen include several different entities, some of which are unique to that organ. Twenty-two such proliferations were studied, including 10 hemangiomas, six littoral cell angiomas, four angiosarcomas, and two hamartomas. The hemangiomas included seven with localized tumors and three with diffuse angiomatosis of the spleen. All cases were studied by paraffin section immunohistochemistry with a large panel of antibodies. In addition, all cases were studied for the presence of the Kaposis sarcoma-associated herpesvirus (KSHV) using the polymerase chain reaction. The morphologic findings were similar to those previously reported. All proliferations were vimentin positive, and one angiosarcoma was focally keratin positive. All cases reacted for CD31, whereas 20 of 22 were positive for von Willebrands factor and 19 of 22 were positive for Ulex europeaus. CD34 expression in lining cells was identified in 10 of 10 hemangiomas, two of four angiosarcomas, and one of two hamartomas, whereas all six cases of littoral cell angioma were negative. CD68 was expressed in all cases of littoral cell angioma but was also positive in all three diffuse hemangiomas, two of seven localized hemangiomas, and two of four angiosarcomas. CD21 expression was restricted to the lining cells of littoral cell angioma, and CD8 expression was only identified in two of two hamartomas and two of four angiosarcomas. KSHV was not detected in any of the cases. These findings suggest that there are distinct immunophenotypic as well as morphologic features of splenic vascular tumors. Littoral cell angiomas have a characteristic CD34-/CD68+/CD21+/CD8- immunophenotype and hamartomas have a characteristic CD68-/CD21-/CD8+ phenotype. The frequent CD68 expression in diffuse hemangioma suggests an immunophenotypic difference from localized hemangioma of the spleen.

Immunoglobulin gene rearrangements in Hodgkin's disease

An initial survey of biopsy specimens from 16 cases of Hodgkins disease revealed clonal immunoglobulin gene rearrangements in one specimen, which contained large numbers of Reed-Sternberg (R-S) cells. As a result of this finding, the configuration of immunoglobulin and T-cell receptor gene DNA was investigated in biopsy tissues from other cases that were histologically and immunophenotypically consistent with Hodgkins disease and contained numerous R-S cells. In six of seven such specimens (all of the nodular sclerosing subtype), selected solely on the basis of high R-S cell content and sufficient frozen tissue for study, at least one immunoglobulin gene was found to be rearranged in a clonal manner. Additionally, tissue samples obtained at two different time points from the original patient who showed immunoglobulin gene rearrangements revealed identical patterns of rearrangement. In the majority of cases, only a single gene showed rearrangement, and the rearranged bands in Southern blot autoradiograms were usually considerably less intense than the germline bands. No rearrangements of T-cell receptor DNA were detected in any case with a probe for the beta T-cell receptor gene. The results suggest that clonal cell populations possessing uniform immunoglobulin gene rearrangements are present in tissue in some cases of Hodgkins disease. It is not possible to determine which cells contain these rearranged genes, but the increased incidence of detectable rearrangements in cases with high numbers of R-S cell raises the possibility that immunoglobulin gene rearrangement occurs in these cells.

Detection of t(2;5) in anaplastic large cell lymphoma: comparison of immunohistochemical studies, FISH, and RT-PCR in paraffin-embedded tissue.

Anaplastic large cell lymphoma (ALCL) is associated with the t(2;5)(p23;q35) translocation involving the anaplastic lymphoma kinase gene (ALK) and the nucleophosmin gene (NPM), which result in expression of a novel fusion protein, NPM-ALK (p80). Clinicopathologic studies have shown that ALK expression in ALCL is associated with improved 5-year survival rates when compared with ALCL lacking ALK expression. This study used paraffin-embedded tissue to compare interphase fluorescence in situ hybridization (FISH) and reverse transcriptase-polymerase chain reaction (RT-PCR) for the detection of t(2;5) with immunohistochemical analysis for the detection of ALK protein expression in 27 patients with CD30-positive ALCLs. ALK protein expression was detected with ALK1 antibody in 14 of the 27 patients. The neoplastic cells in 13 of these 14 lymphomas reacted with the p80NPM/ALK antibody. FISH, using a two-color ALK DNA probe, correlated 100% with the immunohistochemical results: a translocation involving the ALK gene was detected in all 14 lymphomas that reacted with anti-ALK1. RT-PCR, performed on 21 lymphomas, detected NPM-ALK mRNA in five of the lymphomas, all of which reacted with anti-ALK1 and showed ALK gene rearrangement by FISH. Lymphomas showing ALK1 reactivity occurred in a younger patient population (median age, 19.5 years) and were associated with improved 5-year survival rates (84%), as compared with lymphomas lacking ALK1 reactivity (median age, 68.0 years; 5-year survival rate, 35%; p = 0.008). We conclude that immunohistochemical studies, using antibody ALK1. and FISH for ALK gene rearrangement are equally effective for identifying patients with ALCL who have a favorable clinical outcome.

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

The histologic and immunologic features of an unusual morphologic expression of nodular sclerosing Hodgkins disease, which has been termed the “syncytial variant,” are described. In biopsy material from 18 cases, numerous Reed-Sternberg cell variants were observed in sheets and cohesive clusters, and at least focal evidence of nodular sclerosis was present in each case. The granulocyte antibody anti-Leu Ml reacted with antigenic determinants in Reed-Sternberg cells and atypical variants thereof in 13 of the 18 cases; the lack of staining with antibodies reactive with the leukocyte common (T200) antigen (PD7/26), keratin (AE1), and SI00 protein (polyclonal anti-SlOO) was helpful in excluding non-Hodgkins lymphoma, carcinoma, and melanoma, respectively. This unusual form of nodular sclerosing Hodgkins disease is important to recognize, since it may simulate metastatic neoplasms, thymoma, and non-Hodgkins lymphoma.

Proliferative rates of non-Hodgkin's lymphomas as assessed by Ki-67 antibody

The Ki-67 antibody, a monoclonal antibody that reacts with nuclei in actively proliferating cells, was used in an immunohistochemical study to assess the growth fractions of non-Hodgkins lymphomas and related disorders. The lowest proliferative indices were found in small lymphocytic lymphoma/chronic lymphocytic leukemia and intermediate lymphocytic/mantle zone lymphoma. An intermediate proliferative index was seen in the follicular lymphomas and diffuse small cleaved cell and diffuse mixed cell lymphomas. A high index was seen in the diffuse large cell lymphoma and lymphoblastic lymphoma. The highest and most consistent proliferative index was seen in small noncleaved cell lymphoma. Cases of reactive follicular hyperplasia had a significantly higher proliferative index than those of follicular lymphoma. We conclude that the Ki-67 antibody has great utility in providing an estimate of the proliferative rate of non-Hodgkins lymphomas. Prospective studies may show this information to have prognostic value independent of histologic classification.

Immunohistology of pityriasis lichenoides et varioliformis acuta and pityriasis lichenoides chronica: Evidence for their interrelationship with lymphomatoid papulosis

Pityriasis lichenoides et varioliformis acuta and pityriasis lichenoides chronica are idiopathic, papular eruptions that exhibit certain clinicopathologic similarities to each other and to lymphomatoid papulosis. In order to determine if these disorders are also similar immunologically, we studied the immunopathology of five biopsy specimens from three cases of pityriasis lichenoides et varioliformis acuta and three biopsy specimens from three cases of pityriasis lichenoides chronica. We then compared them to our prior immunohistologic study of nine cases of lymphomatoid papulosis. Pityriasis lichenoides et varioliformis acuta and pityriasis lichenoides chronica both exhibited a dermal and epidermal infiltrate of CD4+ and CD8+ T cells expressing activation antigens. These were admixed with numerous macrophages. The lesional epidermis was diffusely human lymphocyte antigen (HLA)-DR+ and contained decreased CD1+ dendritic cells. Endothelial cells were also HLA-DR+. Cells bearing the phenotypes of B cells, follicular dendritic cells, or natural killer/killer cells were essentially absent. Except for the lack of large atypical cells, the results resembled those described previously for lymphomatoid papulosis. These findings indicate that pityriasis lichenoides chronica, pityriasis lichenoides et varioliformis acuta, and lymphomatoid papulosis share several immunohistologic features. Together with certain clinicopathologic similarities, they are consistent with the hypothesis that these three disorders are interrelated.

Intermediate lymphocytic lymphoma: An immunophenotypic study with comparison to small lymphocytic lymphoma and diffuse small cleaved cell lymphoma

Sixteen cases of intermediate lymphocytic lymphoma (ILL), including eight cases with mantle zone architecture, were studied using cryostat sections, a biotin-avidin immunoperoxidase technique, and a large panel of monoclonal antibodies. The neoplastic cells invariably expressed IgM, most B lineage antigens (B1, TO15, Leu-12, 6A4, 41H, BA-1, and LN-2), and Ia. IgD was expressed in 12 cases. Leu-1 and Leu-8 were weakly expressed by the tumor cells in 12 and 11 cases, respectively. The neoplastic cells did not express common acute lymphoblastic leukemia antigen (CALLA) or the T10 antigen in any case. Because ILL is difficult to differentiate from small lymphocytic lymphoma (SLL) and diffuse small cleaved cell lymphoma (DSCCL) on the basis of light microscopic criteria, the immunologic findings of ILL were compared to 31 cases of B cell SLL and 11 cases of B cell DSCCL previously studied in the laboratory to determine if immunologic findings might aid in the distinction. No absolute, and five statistically significant, differences were found; IgD in combination with IgM was seen more commonly in cases of ILL and DSCCL than in SLL (P less than .01), IgG was found more often in SLL than in ILL and DSCCL (P less than .05), Leu-8 was more commonly expressed in ILL and SLL than in DSCCL (P less than .05), T9 expression was less frequent in ILL as compared with SLL (P less than .05) and more proliferating cells were seen in ILL and DSCCL than in SLL (P less than .01). The investigators conclude that these three classes of lymphoma are remarkable much more for their immunologic similarities than for their differences and that immunologic studies are of limited usefulness in differentiating the three neoplasms. Their results also support the concept that these lymphomas are closely related to each other. In particular, DSCCL immunologically appears to be more closely related to SLL and ILL than to follicular small cleaved cell lymphoma.

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

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

Monoclonal antibodies reactive in routinely processed tissue sections of malignant lymphoma, with emphasis on T-cell lymphomas

The immunoreactivity of eight monoclonal antibodies was evaluated on 45 routinely processed lymphomas (22 T-cell lymphomas, 11 B-cell lymphomas, and 12 cases of Hodgkins disease). Two antibodies reactive with leukocyte common (T200) antigens (PD7/26 and 2B11) stained most of the B- and T-cell lymphomas but did not stain the Reed-Sternberg cells and variants in Hodgkins disease. Two antibodies known to stain B cells (LN-1 and LN-2) reacted with some of the B-cell lymphomas, but LN-2 also reacted with the neoplastic cells in six of 22 T-cell lymphomas and with the Reed-Sternberg variants in eight of 12 cases of Hodgkins disease. The granulocyte antibody anti-Leu M1 reacted with most cases of Hodgkins disease but also reacted with two of 11 B-cell non-Hodgkins lymphomas. An antibody to epithelial membrane antigen (anti-EMA) stained some cases of T-cell lymphoma, B-cell lymphoma, and Hodgkins disease. Leu 7 was expressed in one T-cell lymphoma and in one case of Hodgkins disease. A novel antibody reactive with T cells (L60) stained all cases of T-cell lymphoma but also stained some cases of B-cell lymphoma and one case of Hodgkins disease. We conclude that none of these antibodies, when used alone on routinely fixed paraffin-embedded material, is completely sensitive and specific for T-cell lymphoma, B-cell lymphoma, or Hodgkins disease. However, a panel of antibodies is useful in distinguishing Hodgkins disease from non-Hodgkins lymphoma and in suggesting the B- or T-cell phenotype of non-Hodgkins lymphomas.

Splenic mesothelial cysts mimicking lymphangiomas

Lymphangiomas of the spleen may occur as part of lymphangiomatosis or may represent solitary lesions. Solitary splenic lymphangiomas are described traditionally as subcapsular, multicystic proliferations that are often incidental findings. Six cases of splenic tumors with morphologic features similar to those described for solitary lymphangioma were studied using an immunohistochemical panel that included epithelial and vascular markers. None of the patients had evidence of lymphangiomatosis, and all tumors were incidental findings in splenectomy specimens. All cases demonstrated lining cells that were positive for keratin and the mesothelial cell-associated antibody HBME-1 but were negative for the vascular markers Factor VIII-related antigens, CD31, and CD34. The immunohistochemical findings are suggestive of a mesothelial derivation of these multicystic proliferations rather than representing true lymphangiomas.