Recent advances in cutaneous lymphoma-implications for current and future classifications

The Revised European-American Classification of mature lymphoid neoplasms published in 1994 and the 2001, 2008 and 2016 WHO classifications that followed, were the product of international collaboration and consensus amongst haematopathologists, geneticists, molecular scientists and clinicians. Primary cutaneous lymphomas were fully incorporated into this process following the publication of the WHO-EORTC classification of cutaneous lymphomas in 2005. The definition, diagnostic criteria and recommended studies for primary cutaneous lymphoma continue to be refined. The 2022 International Consensus Classification represents the most recent update and an overview of all the main entities presenting primarily in the skin, together with the major changes in classification, are summarized herein. Primary cutaneous marginal zone lymphoma is segregated from other extranodal marginal zone lymphomas of mucosa-associated lymphoid tissue (MALT lymphoma) and downgraded to a lymphoproliferative disorder in line with its markedly indolent behaviour. In addition, two subtypes are recognised, based largely but not exclusively on whether they are heavy chain class-switched or IgM positive. Similarly, in keeping with a trend to greater conservatism, primary cutaneous acral CD8 positive T cell lymphoma is now also classified as a lymphoproliferative disorder. In addition, significant new insights into the biology of primary cutaneous lymphoma have also recently been forthcoming and will be presented. These studies have enhanced our knowledge of genetic, epigenetic and transcriptional changes in this group of diseases. They not only identify potential targets for novel therapies, but also raise as yet unanswered questions as to how we categorise cutaneous lymphomas, particularly with respect to relationships with similar lymphomas at extracutaneous sites.

Phase II study of short course CHOP-rituximab (R) followed by ibritumomab tiuxetan (IT) as first-line treatment for follicular lymphoma (FL)

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Background: Therapy with CHOP-R and radioimmunotherapy (RIT) is a promising treatment for untreated FL. Press reports complete responses (CR) of 69% in FL patients (pts.) with 6 cycles of CHOP followed by I-131 tositumomab. We report efficacy and safety using 3 cycles of CHOP-R followed by IT and extended R. Methods: Eligibility criteria include symptomatic or grade 3 untreated FL. 60 pts. have been accrued and 47 evaluated. The treatment consists of two phases: CHOP-R for 3 cycles followed by IT. One week after IT, pts receive R weekly × 4. Bone marrow (BM) biopsies and fusion PET-CT scans are obtained at baseline, after CHOP-R, and 12 weeks post RIT. The primary endpoint is CR rate. CR requires a neg. PET scan and conventional Working Group criteria. Results: Toxicity data are available for 47 pts of median age 56 (range, 39–78), 44 of whom completed both phases of therapy and are evaluated for response. Characteristics and CR rates after IT are shown: 3 pts. did not receive RIT (1 second malignancy, 1 non-compliance, 1 septic death). Of the 44, CR after CHOP-R is 41%. After IT, CR improved to 89%. Of the 5 pts who did not achieve CR, 3 had neg. PET scans (2 with PR, 1 with SD by CT), and 2 had residual disease by PET with PR by CT. At a mean follow-up of 16 months (range, 6–33 months), there are 4 relapses: 3 who achieved CR by PET-CT, 1 with PR by PET-CT. Toxicity was predominantly myelosuppression. There was 1 episode of febrile neutropenia after RIT. Conclusions: 3 cycles of CHOP-R followed by IT and R achieve a high CR in previously-untreated pts. with FL. Addition of RIT increased CR from 41% to 89%. Data will be presented on the affect of bulky disease, positive BM, grade 2 or 3 histology, and high FLIPI score on CR. Further follow-up is necessary to evaluate response duration and determine whether there is a correlation with early or late CR.

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Update on extranodal lymphomas. Conclusions of the Workshop held by the EAHP and the SH in Thessaloniki, Greece

Classification and proper treatment of extranodal lymphoma is hindered by the diversity of lymphoma types and the relative rarity of many of these tumour types. In order to review controversial issues in extranodal lymphoma diagnosis, a joint Workshop of the European Haematopathology Association (EAHP) and the Society for Hematopathology (SH) was held, where 99 selected cases were reviewed and discussed. This Workshop summary is focused on the most controversial aspect of cutaneous B-cell lymphoma, other extranodal B-cell lymphomas, plasmablastic lymphoma and anaplastic large-cell lymphoma in extranodal sites, and makes practical recommendations about diagnosis and therapeutic approaches.

Primary pleural effusion posttransplant lymphoproliferative disorder: Distinction from secondary involvement and effusion lymphoma

Pleural effusion presentation of posttransplant lymphoproliferative disorder (PTLD) is relatively uncommon. Most examples of effusion-based PTLD have been secondary to widespread solid organ involvement, and are associated with an aggressive clinical course. We report on a case of primary effusion PTLD in a 70-yr-old male liver transplant recipient with a history of hepatitis B infection. Cytomorphologically, the pleural fluid specimen showed a monomorphous population of intermediate to large-sized transformed lymphoid cells, with irregular multilobated nuclear contours and readily identifiable mitotic figures. Flow cytometric immunophenotypic studies revealed a CD5-negative, CD10-negative, lambda immunoglobulin light chain-positive, monoclonal B-lymphocyte (CD19-positive/CD20-positive) population. The immunocytochemical stain for CD30 antigen was negative. In situ hybridization study for Epstein-Barr virus (EBV) early RNA (EBER) and Southern blot analysis for EBV terminal repeat sequences were both positive. Southern blot analysis for human herpes virus-8 (HHV-8) was negative. No solid-organ PTLD was identified, and the cytologic results supported the diagnosis of primary effusion PTLD. Immunosuppression was decreased, and 8 mo following the diagnosis of pleural fluid PTLD, the patient was stable and his pleural effusion had markedly diminished. Recognition of primary effusion PTLD and its distinction from PTLD secondarily involving the body fluids and from other lymphomas is important, since the behavior and prognosis appear different.

Is lymphoplasmacytic lymphoma/immunocytoma a distinct entity? A clinicopathologic study of 20 cases

Lymphoplasmacytic lymphoma/immunocytoma (LLI) was defined initially as a small B-cell lymphoma with plasmacytoid or plasmacytic features. Because other types of small B-cell lymphoma, particularly marginal zone B-cell lymphoma may exhibit plasmacytic differentiation, the revised European-American lymphoma classification and World Health Organization has defined LLI more narrowly to exclude other small B-cell lymphomas. The goal of this study was to reevaluate LLI as a clinicopathologic entity. Twenty cases were selected from 43 previously diagnosed as "small lymphocytic lymphoma, plasmacytoid" or "immunocytoma" from 1985 to 1998. Cases fulfilling the criteria for B-cell small lymphocytic lymphoma, follicular lymphoma, marginal zone B-cell lymphoma, or other types of B-cell lymphoma were excluded. The histopathology and immunoreactivity for CD20, CD79a, CD3, CD43, CD23, CD5, kappa, lambda, and immunoglobulins (Ig's) M, G, and A were reviewed, in addition to available clinical findings. There were 13 men and seven women, with a mean age of 69 years. Five patients had documented Waldenström's macroglobulinemia (WM). Three architectural patterns were observed. Pattern A (seven of 20) showed open sinuses, small follicles, and hemosiderosis; pattern B (four of 20) showed hyperplastic follicles; and pattern C (nine of 20) showed diffuse effacement. Epithelioid histiocytes were prominent in patterns B and C but absent in A. Cytologically, six of 20 were polymorphous with 10% to 40% transformed cells; 14 of 20 were lymphoplasmacytic. Five cases showed minor foci of monocytoid B cells. One case showed a composite histology of LLI and small lymphocytic lymphoma. Amyloid was present in two cases. All cases were CD20 and/or CD79a immunoreactive, with two of 20 positive for CD43. Twelve cases were kappa monoclonal and eight cases were lambda monoclonal. Twelve of 17 cases that could be evaluated were positive for IgM and five were positive for IgG. All cases were negative for CD5 and CD23 with the exception of the one case with a composite histology. Eleven of 20 patients with available follow-up died of disease (median, 48 months), and eight of 20 are alive with disease at a follow-up of 6 months to 2 years. LLI does appear to represent a distinct clinicopathologic entity even though it shows morphologic heterogeneity and overlapping features with marginal zone B-cell lymphoma and small lymphocytic lymphoma. Recognition of LLI is important because the overall prognosis may be worse than for other types of small B-cell lymphomas.

Hepatosplenic and subcutaneous panniculitis-like gamma/delta T cell lymphomas are derived from different Vdelta subsets of gamma/delta T lymphocytes

Gamma/delta T cell lymphomas (gamma/delta TCL) represent rare, often aggressive types of T cell malignancy that are clinically and pathologically diverse. Most gamma/delta TCL occur as a hepatosplenic or subcutaneous type. To date, analysis of the T cell receptor delta (TCRS) gene repertoire of hepatosplenic gamma/delta TCL (gamma/delta HSTCL) and subcutaneous panniculitis-like gamma/delta TCL (gamma/delta SPTCL) has been reported only in a limited number of cases. In this study we analyzed 11 gamma/delta HSTCL and 4 gamma/delta SPTCL by polymerase chain reaction and immunostaining to determine their usage of the Vdelta subtypes (Vdelta1-6). It is noteworthy that 10 of 11 gamma/delta HSTCL expressed the Vdelta1 gene. The remaining case also expressed T cell receptor delta (TCRS) as determined by flow cytometry and TCRdelta rearrangement in Southern blot. However, the Vdelta gene expressed by this lymphoma could not be determined, which suggests usage of an as yet unidentified Vdelta gene. In striking contrast to the gamma/delta HSTCL, all 4 gamma/delta SPTCL expressed the Vdelta2 gene. Our data demonstrate that gamma/delta HSTCL are preferentially derived from the Vdelta1 subset of gamma/delta T lymphocytes, whereas gamma/delta SPTCL are preferentially derived from the Vdelta2 subset. The pattern of Vdelta gene expression in HSTCL and SPTCL corresponds to the respective, predominant gamma/delta T cell subsets normally found in the spleen and skin. This finding suggests that gamma/delta TCL are derived from normal gamma/delta T lymphocytes which reside in the affected tissues. Furthermore, the selective, lymphoma type-specific Vdelta gene segment usage may provide a molecular tool to distinguish better among various types of gamma/delta TCL lymphoma particularly in the clinically advanced, widely disseminated cases.

Immunophenotypic and genotypic markers of follicular center cell neoplasia in diffuse large B-cell lymphomas

Diffuse large B-cell lymphomas (DLBCL) are a biologically and clinically heterogeneous entity. Although some DLBCL represent transformation of follicular lymphomas (FL), the proportion that is of follicular center cell (FCC) origin remains uncertain. Immunophenotypic and genotypic markers used to suggest a FCC origin for a lymphoma (bcl-6 and CD10 expression, lack of CD138 expression, bcl-2 rearrangements [R]) or to subdivide DLBCL (bcl-2 expression, bcl-6 R) were therefore investigated in 22 FL and 44 DLBCL using paraffin section immunostains and Southern blot/polymerase chain reaction analysis. All FL tested were bcl-6+ (19) and CD138- (22) with 16/19 also bcl-2 and CD10+ (classic phenotype), one bcl2+, CD10- (grade III) and two bcl2-, CD10+ (grade II or III). Bcl-2R was identified in 4/5 FL-GrI, 3/6 FL-GrII, and 1/3 FL-GrIII. Bcl-6R was found in 0/5, 2/4, and 0/3 FL, respectively. All but 3/41 DLBCL were bcl-6+ with 17/37 also bcl-2+ and CD10+. Three of these cases were also CD138+. Twelve bcl-6+ cases were bcl-2+, CD10-, six bcl-2-, CD10+, and two bcl-2-, CD10-. The three bcl-6- cases were bcl-2+, CD138- and two were CD10+. Bcl-2R was identified in 5/27 DLBCL with 4/5 bcl-2+, 3/4 tested CD10+ and 4/4 bcl-6+. Bcl-6R was identified in 7/26 including three with a classic FL phenotype. The vast majority of DLBCL in this study have an immunophenotype that supports a FCC origin. Although the proportion of DLBCL that co-expressed bcl-6, CD10 and bcl-2 was lower than for the FL, absence of bcl-2 or CD10 may be associated with higher grade FL It is also possible that bcl-6 expression is not completely specific for a FCC origin. Only a minority of cases suggested postfollicular differentiation. Only a minority of DLBCL show bcl-2R, suggesting that many have a different molecular pathogenesis than most low-grade FL. Bcl-6R did not exclude a FCC origin.

Salivary gland mucosa-associated lymphoid tissue lymphoma immunoglobulin V(H) genes show frequent use of V1-69 with distinctive CDR3 features

Salivary gland mucosa associated lymphoid tissue (MALT) type lymphomas are B-cell neoplasms that develop out of a reactive infiltrate, often associated with Sjögren's syndrome. Previous reports from our laboratory involving 10 patients suggested these lymphomas expressed a restricted immunoglobulin (Ig) V(H) gene repertoire with over use of V1-69 gene segments. To better determine the frequency of V1-69 use and whether there may also be selection for CDR3 structures, we sequenced the V(H) genes from 15 additional cases. Over half of the potentially functional V(H) genes (8 of 14) used a V(H)1 family V1-69 gene segment, whereas the other cases used different gene segments from the V(H)1 (V1-46), V(H)3 (V3-7, V3-11, V3-30.3, V3-30.5), and V(H)4 (V4-39) families. The 8 V1-69 V(H) genes used 5 different D segments in various reading frames, but all used a J4 joining segment. The V1-69 CDR3s showed remarkable similarities in lengths (12-14 amino acids) and stretches of 2 to 3 amino acids between the V-D and D-J junctions. They did not resemble CDR3s typical of V1-69 chronic lymphocytic leukemias. This study extends our earlier work in establishing that salivary gland MALT lymphomas represent a highly selected B-cell population. Frequent use of V1-69 appears to differ from MALT lymphomas that develop at other sites. The high degree of CDR3 similarity among the V1-69 cases suggests that different salivary gland lymphomas may bind similar, if not identical epitopes. Although the antigen specificities are presently unknown, similar characteristic CDR3 sequences are often seen with V1-69 encoded antibodies that have anti-IgG or rheumatoid factor activity. (Blood. 2000;95:3878-3884)

Classification of small B-cell lymphoid neoplasms using a paraffin section immunohistochemical panel

Immunophenotypic analysis is critical in categorizing small B-cell neoplasms; however, many recommended antibody panels have required fresh or frozen tissue. Many paraffin-reactive antibodies are now available but have been studied mostly in isolation. Therefore, the utility of a panel of paraffin-reactive antibodies in differentiating small B-cell neoplasms was investigated. Paraffin-embedded sections of small lymphocytic lymphoma/B-chronic lymphocytic leukemia (SLL/B-CLL; 12), mantle cell (MCL; 15), follicular (FL; 11), and marginal zone B-cell (MZL; eight) lymphomas were stained with CD20/L26, CD3, CD43/DF-T1 or Leu22, CD5/4C7, CD23/BU38, cyclin D1/H295, and CD10/56C6 antibodies. For select antibodies, results were compared to flow cytometric data (FC). Formalin and B5 fixation were also compared. Seven of 11 SLL/B-CLL were CD43+ CD5+ CD23+ cyclin D1- CD10-; seven of 11 MCL were CD43+ CD5+ CD23- cyclin D1+ CD10-; nine of 10 FL were CD43- CD5- CD23- cyclin D1- CD10+; and five of six MZL were CD43+ CD5- CD23- cyclin D1- CD10-. CD5, CD23, and CD10 stains showed sensitivities of 81, 88, and 100%, respectively, compared to FC. With B5 fixation, cyclin D1 was more often negative and CD5 more often equivocal. A panel of paraffin-reactive antibodies aids in classification of small B-cell neoplasms, although a small number of cases have indeterminate phenotypes and MZL have no defining features. CD5 separates most SLL/B-CLL and MCL from FL and MZL. CD23 separates SLL/B-CLL from most MCL, but cyclin D1 is most important for identifying MCL. CD10 positivity distinguishes most FL from other small B-cell lymphoid neoplasms.

Epstein-Barr virus-negative post-transplant lymphoproliferative disorders: a distinct entity?

Post-transplant lymphoproliferative disorders (PTLDs) are usually but not invariably associated with Epstein-Barr virus (EBV). The reported incidence, however, of EBV-negative PTLDs varies widely, and it is uncertain whether they should be considered analogous to EBV-positive PTLDs and whether they have any distinctive features. Therefore, the EBV status of 133 PTLDs from 80 patients was determined using EBV-encoded small ribonucleic acid (EBER) in situ hybridization stains with or without Southern blot EBV terminal repeat analysis. The morphologic, immunophenotypic, genotypic, and clinical features of the EBV-negative PTLDs were reviewed, and selected features were compared with EBV-positive cases. Twenty-one percent of patients had at least one EBV-negative PTLD (14% of biopsies). The initial EBV-negative PTLDs occurred a median of 50 months post-transplantation compared with 10 months for EBV-positive cases. Although only 2% of PTLDs from before 1991 were EBV negative, 23% of subsequent PTLDs were EBV negative (p <0.001). Of the EBV-negative PTLDs, 67% were of monomorphic type (M-PTLD) compared with 42% of EBV-positive cases (p <0.05). The other EBV-negative PTLDs were of infectious mononucleosis-like, plasma cell-rich (n = 2), small B-cell lymphoid neoplasm, large granular lymphocyte disorder (n = 4) and polymorphic (P) types. B-cell clonality was established in 14 specimens and T-cell clonality was established in three (two patients). None of the remaining specimens were studied with Southern blot analysis and some had no ancillary studies. Rearrangement of c-MYC was identified in two M-PTLDs with small noncleaved-like features, and rearrangement of BCL-2 was found in one large noncleaved-like M-PTLD. Ten patients were alive at 3 to 63 months (only three patients received chemotherapy). Seven patients, all with M-PTLDs, are dead at 0.3 to 6 months. Therefore, EBV-negative PTLDs have distinct features, but some do respond to decreased immunosuppression, similar to EBV-positive cases, suggesting that EBV positivity should not be an absolute criterion for the diagnosis of a PTLD.

HIV-associated Waldeyer's ring lymphoid hyperplasias: characterization of multinucleated giant cells and the role of Epstein-Barr virus

Lymphoid hyperplasia of Waldeyer's ring (WR) is an often-symptomatic complication of human immunodeficiency virus (HIV) infection. A characteristic but not well explained finding is the presence of multinucleated giant cells (MNGCs) adjacent to crypt or surface epithelium. To further elucidate the MNGCs and assess their relationship to HIV and Epstein-Barr virus (EBV), 12 specimens from 11 HIV-positive patients were stained with antibodies to HIV-1 p24, EBV (latent membrane protein, LMP-1), histiocytes (CD68), and other antigen-presenting cells: S-100 protein, the Langerhans cell (LC) marker CD1a, and the follicular dendritic cell (FDC) marker (CD21). Double immunofluorescent staining to assess co-expression of p24 and cell-specific markers was performed and analyzed by laser-scanning confocal microscopy with 3-dimensional reconstruction. In situ hybridization for EBV-encoded small RNA (EBER) was performed in all cases. Immunostains showed MNGCs labeled for p24, S-100, and CD68, but not CD1a. In 1 case, rare MNGCs were CD21-positive. EBV LMP-1 was uniformly negative, although EBER-positive lymphocytes were seen by in situ hybridization in 9 of 12 specimens (numerous in only 3 specimens). Double immunofluorescent staining showed co-localization of p24 with CD68 and S-100. Our results suggest that MNGCs are generally HIV-infected, EBV-negative, and most likely represent an unusual S-100-positive histiocyte subset (not LC or FDC). Their exact pathophysiologic role remains uncertain. EBV does not appear to play a major role in the pathogenesis of WR lymphoid hyperplasias in HIV infection.

Small B-cell lymphomas of the lymph nodes and spleen: practical insights to diagnosis and pathogenesis

As defined in the proposed World Health Organization classification of neoplastic diseases of the hematopoietic and lymphoid tissues, the small B-cell lymphomas include B-cell chronic lymphocytic leukemia / small lymphocytic lymphoma, mantle cell lymphoma, follicular lymphoma, marginal zone B-cell lymphoma of mucosa-associated lymphoid tissue (MALT) type, nodal marginal zone lymphoma, lymphoplasmacytic lymphoma, and splenic marginal zone B-cell lymphoma. These neoplasms are recognized mostly on the basis of their histopathologic features, but ancillary studies are useful in confirming and sometimes making the diagnosis. Clinically, the small B-cell lymphomas of lymph nodes and spleen (but not those of MALT type) are usually disseminated at diagnosis and considered incurable. With the exception of mantle cell lymphoma, however, they are generally indolent. The small B-cell lymphomas are among the best examples of how malignant lymphomas can be related to the normal immune system. Although uncertainties exist, these lymphomas are generally considered the neoplastic equivalents of normal B-cell compartments. From a molecular perspective, mantle cell and follicular lymphomas are the best characterized. In both cases, there are characteristic chromosomal translocations involving the immunoglobulin heavy chain and the cyclin D1 or bcl-2 genes, respectively, that are probably followed by additional molecular events leading to overt neoplasia. Variable proportions of the small B-cell lymphomas undergo transformation that might be associated with abnormalities in tumor suppressor genes / cell cycle regulatory proteins. After a brief review of normal B-cell development, the major small B-cell lymphomas (except for those of MALT type) will be discussed in terms of their morphologic features, immunophenotype (including paraffin-section immunostaining), genotype, karyotype, and clinical features, including disease evolution.

Subcutaneous panniculitis-like T-cell lymphoma: clinicopathologic, immunophenotypic, and genotypic analysis of alpha/beta and gamma/delta subtypes

Subcutaneous panniculitis-like T-cell lymphoma (SPTCL) is an uncommon cutaneous lymphoma that has been proposed as a distinct clinicopathologic entity, but studies of SPTCL are limited. We studied the clinicopathologic, immunophenotypic, and genetic features of 11 SPTCLs. All cases had a variable admixture of pleomorphic small, medium, or large lymphocytes and histiocytes infiltrating the subcutis in a lobular panniculitis-like pattern. A granulomatous reaction was seen in three cases and erythrophagocytosis in four. Karyorrhexis and fat necrosis were present in all cases. Angioinvasion was seen in seven SPTCLs; four had areas of coagulation necrosis. All cases expressed T-cell-associated antigens (CD3epsilon, CD45RO, or CD43) and T-cell receptors (TCR); nine expressed alphabeta TCRs and two expressed gammadelta TCRs. T-cell receptor-gamma, TCRbeta, or TCRdelta genes were clonally rearranged in 8 of 10 cases studied. Both gammadelta SPTCLs expressed Vdelta2+ TCRs and were CD4-, CD8- and CD56+. CD56 was negative in seven of nine alphabeta SPTCLs and inconclusive in the other two. Six of nine alphabeta SPTCLs were CD8+; the CD4/CD8 phenotypes were indeterminate in the other three. Cytolytic granule-associated proteins were expressed by all SPTCLs (11 of 11 were TIA-1+, 4 of 4 were perforin+). In situ hybridization for Epstein-Barr virus-encoded RNA (EBER-1) was negative in all cases. Most patients responded to systemic chemotherapy or local radiation therapy. Seven patients are alive: four without disease (19-73 months) and three with disease (32-72 months); four died: three of disease (3-25 months) and one without disease (42 months). We conclude that SPTCLs are clonal, EBV-, cytotoxic T-cell lymphomas derived from alphabeta T-cells or gammadelta T-cells. The gammadelta SPTCLs appear to be preferentially derived from the Vdelta2+ subset. Subcutaneous panniculitis-like T-cell lymphoma may be rapidly fatal or indolent; local therapy may be appropriate for some patients.

A near-haploid bone marrow karyotype in systemic mast cell disease: is it characteristic of the disease or an incidental finding?

We present the case of a 40-year-old man with aggressive systemic mast cell disease. The patient had a predominant near-haploid clone in his bone marrow cells, detected by cytogenetic analysis performed at the time of diagnosis. The similarities between this case and a previously published case of near-haploidy in a patient with malignant mastocytosis suggest that near-haploidy may be a characteristic of aggressive systemic mast cell disease rather than an incidental finding.

Clonal and morphological variation in a posttransplant lymphoproliferative disorder: evolution from clonal T-cell to clonal B-cell predominance

The majority of posttransplant lymphoproliferative disorders (PTLD) are Epstein-Barr virus (EBV)-associated and of B-cell origin. A much smaller proportion of PTLD are of T-cell origin. We report the clinical, morphological, immunophenotypic, and genotypic results of a unique PTLD, initially diagnosed as immune mediated thrombocytopenia (ITP), which at presentation was predominantly an anaplastic appearing EBV-associated T-cell PTLD and, after reduction in immunosuppression and the administration of antiviral agents, predominantly an EBV-associated plasma cell rich B-cell PTLD. Subsequent chemotherapy resulted in a complete remission. This case has both practical and biological implications. It highlights how PTLD may be misdiagnosed as other entities, how biclonal cases can have different morphological appearances and include both B- and T-cell clones, how PTLD can evolve over time possibly related to immune reconstitution, and why PTLD should be rebiopsied when the disease does not respond to decreased immunosuppression or recurs.

Clonal salivary gland infiltrates associated with myoepithelial sialadenitis (Sjögren's syndrome) begin as nonmalignant antigen-selected expansions

Myoepithelial sialadenitis (MESA) is the reactive salivary gland lymphoid infiltrate that occurs in patients with Sjogren's syndrome. Although it is well established that mucosa-associated lymphoid tissue (MALT)-type lymphomas may develop from MESA, the issue of whether monoclonal B-cell populations in early MESA-associated lesions represent MALT lymphomas or more benign types of expansions has been very controversial. In addition, it is unknown whether antigen stimulation plays a role in the development or growth of MESA-associated clones. To investigate these issues, we have analyzed the Ig VH genes used by MESA-associated clones in sequential biopsies obtained from contralateral sites of seven different patients. In three cases, single clones were identified in the follow-up biopsies that were distinct from the single clones identified in the initial specimens, whereas in three other cases, the same clone was identified in both the initial and subsequent specimens. In the remaining case, two clones were identified in the second biopsy specimen, one of which was distinct from the initial clone. Of the 11 distinct clones identified in the 14 specimens that were analyzed, 8 were derived from a V1-69 VH gene segment, whereas the other 3 were derived from a V3-7 VH gene segment. In addition, the MESA clones also showed conserved amino acids sequence motifs in their third complementarity-determining regions (CDR3), some of which were encoded by N nucleotides. The marked VH gene restriction along with the similar CDR3 sequences suggests that MESA-associated clones even from different patients may bind the same or similar antigens and are selected for clonal expansion on that basis. The high rates of ongoing VH gene mutation observed in some of the cases futher suggest that the growth of early MESA clones is still dependent on antigen stimulation. In addition, our finding that different biopsies from the same patient may contain distinct clones indicates that some MESA-associated clones have not yet evolved to malignant lymphomas.

Intrahepatic cholestasis due to systemic mastocytosis: a case report and review of literature

A 35-yr-old female presented with symptoms of obstructive jaundice. Liver biopsy, bone marrow aspiration, and biopsy revealed systemic mastocytosis and acute myeloid leukemia. The liver biopsy specimen showed infiltration of mast cells within portal tracts with periductal and portal edema, irregularity of interlobular duct epithelium, and centrizonal cholestasis. Endoscopic retrograde cholangiography was normal. Following chemotherapy treatment with idarubicin and cytarabine for seven days for AML, the bilirubin levels continued to increase for two weeks and then decreased, reaching normal levels in two months. Infiltration of mast cells in the liver leads to hepatomegaly, liver function abnormality and rarely portal hypertension. Intrahepatic cholestasis due to systemic mastocytosis has never been reported. We report a rare case of systemic mastocytosis causing intrahepatic cholestasis that resolved with remission of AML following chemotherapy.

Salivary gland lymphoid infiltrates associated with lymphoepithelial lesions: a clinicopathologic, immunophenotypic, and genotypic study

The criteria for distinguishing benign lymphoepithelial lesions (BLEL) from low grade B-cell lymphomas of mucosa-associated lymphoid tissue (MALT) type in salivary glands and the significance of genotypically documented clonality in this setting are controversial. In addition, the clinical implications of a neoplastic diagnosis are unclear. The histopathologic features of 68 specimens from 49 patients with at least one salivary gland biopsy with LEL together with available clinical data were, therefore, reviewed. Paraffin section immunohistochemical (IHC) stains for kappa, lambda, CD3, CD20, and CD43; in situ hybridization (ISH) for kappa and lambda; and polymerase chain reaction (PCR) for immunoglobulin (Ig) HC rearrangement were performed. The 61 salivary gland specimens were classified as BLEL-13, BLEL with monocytoid B-cell (MBC) halos (BLEL-halo-8), low grade B-cell lymphoma of MALT type with confluent zones of MBC or other atypical lymphocytes (ML-MALT-24), low grade B-cell lymphoma of MALT type with monoclonal plasma cells (ML-MALT-PC-12), and high grade B-cell lymphoma of MALT type (MALT-high grade-4). Soft tissue and perineural invasion was not observed in BLEL and was most common in the MALT lymphomas. Lymph node involvement was identified in six patients at the time of their salivary gland MALT lymphomas but in none with BLEL. CD43+ B cells were seen most commonly in ML-MALT but were present in all other categories except MALT-high grade. Clonal B cells were identified by PCR in 5 of 12 BLEL, 5 of 8 BLEL-halo, 17 of 22 ML-MALT, 6 of 10 ML-MALT-PC, and 3 of 3 MALT-high grade biopsies. All ML-MALT-PC were clonal by ISH or IHC. Repeat biopsies in 14 patients most commonly showed a BLEL/ML-MALT lesion in an ipsilateral or contralateral salivary gland with one transformation to a MALT-high grade. Although only a few patients are known to have received chemoradiation or radiation therapy, most patients with low-grade lesions have pursued an indolent course. These data show the presence of two types of borderline lesions within the spectrum of lymphoid proliferations associated with salivary gland LEL. One has clonal B cells without histological features of neoplasia and the other nonconfluent MBC extending beyond the confines of LEL ("halos"). They share some features with the infrequent nonneoplastic BLEL and others with the more common low-grade B-cell lymphomas of MALT. A few high-grade B-cell lymphomas of MALT were also identified including a rare example of transformation from a low- to high-grade lesion. The optimal therapeutic approach for the borderline and low-grade lesions and the reason why so many of the lymphoproliferative lesions associated with LEL remain localized to the neck remain to be defined.

Cytologic features of post-transplant lymphoproliferative disorder

Post-transplant lymphoproliferative disorders (PTLD) are Epstein-Barr virus (EBV)-associated lymphoid proliferations which affect approximately 2% of organ allograft recipients. Although the histologic features of PTLD are well described, they have been described only rarely in cytologic specimens. The cytomorphologic features of PTLD in body fluid specimens, needle aspirations, and a gastric brushing specimen from seven patients with histologically confirmed PTLD were therefore reviewed. In the cytologic specimens, PTLD was characterized by a mostly polymorphous population of lymphoid cells containing many large transformed lymphocytes, occasional immunoblast-like atypical lymphocytes, necrosis, and, frequently, obvious plasmacytoid differentiation. The presence of EBV was documented in five of the seven cases in the corresponding tissue biopsies. The four patients with PTLD in a body fluid specimen all died within 3 months of detection of the PTLD in the body fluid. The three remaining patients are alive with resolution of PTLD (follow-up of 7, 8, and 14 months). The diagnosis of PTLD should be suggested when cytologic specimens from organ allograft recipients show a polymorphous atypical lymphoid proliferation, frequently with plasmacytoid differentiation and necrosis. Cytologic samples may provide the initial diagnosis of this potentially fatal disease and allow appropriate intervention. The presence of PTLD in a body fluid specimen is a poor prognostic indicator.

Acquired monosomy 7 in donor cells in a patient treated for acute lymphoblastic leukemia with bone marrow transplantation

Two years after a bone marrow transplant (BMT) from his haploidentical mother, a 28-year-old male with a history of acute lymphoblastic leukemia (ALI.) developed myelodysplastic syndrome (MDS) with monosomy 7 in his female bone marrow cells. Follow-up cytogenetic studies, including fluorescence in situ hybridization (FISH) performed twenty-seven and thirty-one months post-BMT consistently showed a female chromosome pattern with monosomy 7. Thirty-six and thirty-nine months post-BMT, further clonal evolution occurred, with the appearance of a sideline of the female cells that first expressed a del(10)(p11.2) and then developed a translocation, t(10;21)(p11.2;q22), in addition to the monosomy 7. Cytogenetic monitoring of this male patient helped to reveal a rare case of early MDS in transplanted donor cells and evolution of the acquired abnormal clone by identifying chromosomal alterations in the donated female bone marrow cells.

Ongoing Ig gene hypermutation in salivary gland mucosa-associated lymphoid tissue-type lymphomas

Salivary gland mucosa-associated lymphoid tissue (MALT) type lymphomas are typically indolent B-cell neoplasms that are often associated with Sjogren's syndrome. To better define the cell of origin and evaluate whether antigen receptor stimulation may be playing a role in tumor growth, the Ig heavy and light chain variable genes (VH and VL) expressed by five salivary gland MALT lymphomas were cloned and sequenced. Comparison to known germline sequences indicated that three of the lymphoma VH genes were derived from 51p1, a member of the VH1 family, while the other two used different VH gene segments from the VH3 family, 22-2B and HG19. All five of the VL genes belonged to the VkIII family, with three derived from Humkv325 and the other two from the Vg and Humkv328 genes. Numerous point mutations relative to the proposed germline genes were present in all of the lymphoma VH and VL genes. In addition, the VH and VL genes from each lymphoma showed intraclonal sequence heterogeneity indicative of ongoing somatic hypermutation. Because the process of Ig gene hypermutation is thought to occur at the germinal center stage of B-cell development, these findings suggest the MALT lymphoma cell of origin may be a germinal center B cell. Selection against mutations that result in replacement of amino acids suggested that Ig stimulation may be important for lymphoma growth. The possibility that antigen receptor stimulation may be involved in the growth of salivary gland MALT lymphomas is further suggested by the noted restricted use of VH and VL gene segments.

Aggressive gastric peripheral T-cell lymphoma of CD8+ type associated with lymphomatous meningitis

Most gastric lymphomas are of B-cell origin, and many are either low-grade or high-grade B-cell lymphomas of mucosa-associated lymphoid tissue type. Gastric T-cell lymphomas are very rare, usually of CD4+ type, and few have had genotypic studies. We report the case of a gastric peripheral T-cell lymphoma of CD8+ type. Genotypic studies demonstrated partial deletion with rearrangement of the T-cell receptor beta-chain gene. Lymphomatous meningitis developed, and the patient died after only 2 months despite chemotherapy. The case is compared with the other gastric T-cell lymphomas that have been reported.

Classification of the posttransplant lymphoproliferative disorders: from the past to the present

Posttransplant lymphoproliferative disorders (PTLD) represent a histopathologic, immunophenotypic, genotypic, and clinical spectrum of disease seen in patients after solid organ and bone marrow transplantation. Because of their great heterogeneity, several classification schemes have been proposed over the past 15 years. Although originally based on morphology and limited immunophenotypic studies, more detailed immunophenotypic and genotypic studies have become increasingly important in the classification of the PTLD. The classifications proposed by Frizzera et al, Nalesnik et al, and Knowles et al are discussed. In addition, some specific types of PTLD recognized in the literature but not distinguished in any of the currently published classifications are presented.

Posttransplant lymphoproliferative disorders: summary of Society for Hematopathology Workshop

Twenty cases of posttransplant lymphoproliferative disorders arising in solid organ allograft recipients (18 patients) or bone marrow allograft recipients (2 patients: 1 autologous; 1 allogeneic) were selected for presentation at the Society for Hematopathology Workshop. In the course of the Workshop discussions, based both on the submitted cases and the combined experience of the participants, it was possible to agree on several distinctive categories of PTLD. These include (1) early lesions, (2) polymorphic posttransplant lymphoproliferative disorders (PTLDs), (3) monomorphic PTLDs (B- and T-cell lymphomas), (4) plasmacytoma-like lesions, and (5) T-cell-rich large B-cell lymphoma/Hodgkin's disease-like lesions. Monomorphic lesions should be classified according to a recognized classification of non-Hodgkin's lymphoma, although specified in the report as PTLD. Polymorphic lesions should be carefully evaluated for clonality; by immunophenotyping; and, if necessary, analysis of antigen-receptor and Epstein-Barr virus (EBV) genomes. Minimal pathological evaluation should include routine morphology, immunophenotyping on fresh tissue (flow cytometry or frozen section), and preservation of tissue for molecular genetic analysis. Analysis of the presence of EBV can be useful in establishing whether early or equivocal lesions represent PTLD (EBV+) or unrelated processes, but is not required in most cases. The pathologist can make an important contribution to the management of patients with PTLD by providing a complete diagnostic evaluation of the biopsy specimens (this is the least expensive part of the care of a transplant patients, not a place to try to cut costs) and making sure the attending physicians understand the special issues in management of PTLD.

A case-control study of hematopoietic and lymphoid neoplasms: the role of work in the chemical industry

The present case-control study was conducted in an effort to determine if work in the chemical industry is related to excesses of certain hematopoietic and lymphoid neoplasms. Cases who died from non-Hodgkin's lymphoma, multiple myeloma, and leukemia were matched by race, gender, age, year of death, and county of residence to controls who died from cardiovascular disease. A total of 618 (309 matched pairs) white male residents of Kanawha County, WV, aged 23-96, who had died between 1965 and 1990 were identified. Conditional logistic regression was conducted and yielded an association between chemical industry work and death due to non-Hodgkin's lymphoma, multiple myeloma, and lymphoid leukemia among subjects who died at age < 65. These results are consistent with the findings of previous studies linking work in chemical manufacturing to hematopoietic and lymphoid neoplasms, and indicate that the excesses may be related to the occupational exposures in men who died at younger ages.

Analysis of the cyclin-dependent kinase inhibitors p18 and p19 in mantle-cell lymphoma and chronic lymphocytic leukemia

BACKGROUND

Mantle-cell lymphoma (MCL) is characterized by overexpression of the G1 cyclin, cyclin D1, strongly implicating this cell-cycle regulatory element in MCL pathogenesis. Recently, loss-of-function mutations in cell-cycle negative regulatory elements, including p53 point mutations and deletions of the cyclin-dependent kinase inhibitors (CDKI) p15 and p16 have been described in a subset of MCLs and have been associated with aggressive clinical course, blastic morphology, and extranodal dissemination. The objective of the present study was to analyze two newly identified members of the p16 (INK4A; MTS1) CDKI family, p18 and p19, in MCL. Such analyses have not been previously reported.

PATIENTS AND METHODS

DNA was isolated from tissue biopsies, peripheral blood cells, or bone marrow cells of 45 patients with MCL and 15 with chronic lymphocytic leukemia (CLL). Southern blot analysis was performed with p18 and p19 probes and compared to placental control DNA and to control probe hybridizations for evidence of p18 or p19 gene deletion or rearrangement.

RESULTS

P18 deletion was identified in one MCL but in no case of CLL. One MCL sample had rearrangement of the p18 gene; this case also had coexisting homozygous p15 and p16 deletion. Both cases with p18 abnormalities had blastic morphology, and one had extranodal disease with renal parenchymal invasion.

CONCLUSIONS

P18 rearrangement or deletion as detected by Southern blot is a rare event in MCL, but may be associated with blastic morphology. P53 mutations and deletions of the CDKI p15 and p16 appear to be more frequent in MCL, although further studies are necessary to assess the presence of inactivating point mutations or altered expression of p16 family proteins.

Congenital muscular dystrophy with primary laminin alpha2 (merosin) deficiency presenting as inflammatory myopathy

Ten laminin alpha2-deficient patients were identified by both immunofluorescence and immunoblotting (30% of congenital muscular dystrophy patients tested). Three of the laminin alpha2-deficient patients were carrying a diagnosis of infantile polymyositis prior to immunostaining studies. The clinical features in the 10 merosin-deficient patients were homogeneous, with severe floppiness at birth, delay in achievement of motor milestones, and magnetic resonance imaging findings of white matter changes with normal intelligence. The 10-kb laminin alpha2-coding sequence was screened for causative mutations by reverse transcriptase-polymerase chain reaction/single-stranded conformational polymorphism analysis in muscle biopsy specimens from 5 patients, followed by automatic sequencing of aberrant conformers. Clear loss-of-function deletion mutations were identified in both alleles of 1 patient. Muscle histopathology in this patient showed a striking inflammatory infiltrate of T cells and B cells. Reexamination of biopsy specimens from other laminin alpha2-deficient patients showed minor signs of inflammation in each. Based on these findings and the histological and clinical picture suggesting failure of muscle regeneration, a pathogenesis model for this major subset of congenital muscular dystrophy is proposed. Our data show that muscle histopathology showing a neonatal inflammatory process should be considered consistent with congenital muscular dystrophy.

Immunohistochemical characterization of mast cell disease in paraffin sections using tryptase, CD68, myeloperoxidase, lysozyme, and CD20 antibodies

To date, the diagnosis of mast cell disease (MCD) relied on routine plus histochemical stains. Its differential diagnosis, however, includes a variety of other hematopoietic and particularly B-cell lymphoid neoplasms that are best identified in paraffin sections using immunostains. To determine the paraffin-section immunoreactivity of MCD, 20 specimens from 14 patients with MCD and 1 bone marrow sample (from a patient with probable MCD) that showed equivocal metachromasia, were stained with antitryptase, CD68 (KP-1), CD20 (L26), antilysozyme, and antimyeloperoxidase antibodies. Ten hairy cell leukemias (HCLs), six lymphomas of parafollicular and/or monocytoid B-cell (MBCLs) and low-grade mucosa-associated lymphoid tissue (MALT) types, six granulocytic sarcomas, and five acute myeloid leukemias with monocytic differentiation (M4 and M5 types) were also stained. Tryptase positivity was identified in all of the MCD cases. The staining was moderate to strong in 20 of the 21 specimens, including the probable MCD case. No other neoplasms tested were tryptase positive. CD68 showed similar to even stronger staining in all of the specimens of MCD, HCL, granulocytic sarcoma, and acute myeloid leukemia (M4 and M5 types) tested and in five of the six MBCL and/or MALT-type lymphomas. Weak-to-moderate lysozyme staining seemed to be present in at least 7 of the MCD specimens, whereas there was a lack of staining for myeloperoxidase in 12 specimens, and 7 specimens were nonevaluable (1 case was not tested). Myeloperoxidase was identified in all of the granulocytic sarcomas and acute myeloid leukemias (M4 and M5 types) but not in any HCLs, MBCLs, or low-grade lymphomas of MALT type. CD20 was negative in all of the MCD and myelomonocytic neoplasms but positive in all of the HCLs, MBCLs, and low-grade B-cell lymphomas of MALT type. MCD, therefore, has a characteristic tryptase-positive, CD68-positive, and CD20-negative phenotype in paraffin sections. This distinguishes MCD from the hematopoietic and/or lymphoid disorders that it most closely resembles.

Primary lymphoma of the skull presenting as multiple cranial nerve palsies

Lymphoma presenting with isolated diffuse infiltration of the skull is exceedingly rare, with less than 20 previously reported cases. The clinical presentation of a 73-year-old female with primary lymphoma of the skull, manifesting multiple cranial nerve palsies and infiltration of the temporalis muscles is described. MRI of the head, revealed an abnormal signal from the diploic space of the call varium and skull base on both T1 and T2 weighted images, infiltration of the temporalis muscles and clivus, and diffuse meningeal enhancement encroaching on the cavernous sinus bilaterally. Biopsy of temporalis muscle and skull showed a diffuse large cell lymphoma, B-cell type. Staging workup failed to reveal any other sites of disease. Despite multiple cranial nerve palsies, there was no evidence of leptomeningeal disease on CSF examination. MRI was instrumental in demonstrating the abnormalities that lead to the diagnostic biopsy.

A clonally distinct recurrence of Burkitt's lymphoma at 15 years

A human immunodeficiency virus-negative male was successfully treated for two occurrences of Burkitt's lymphoma, 15 years apart. As consolidation of his second remission, he underwent high-dose chemotherapy with peripheral blood stem cell transplantation. In an effort to prove whether the second lymphoma was a relapse of the first or a second primary lymphoma, we obtained paraffin-embedded material from both lymphomas. DNA was extracted from this material and amplified by polymerase chain reaction (PCR) using consensus JH and VH region primers. Analysis of the PCR products, which mostly reflects VDJ joints, showed two sharp bands of different molecular size, proving the monoclonal nature of the lymphomas and suggesting that each had different Ig gene rearrangements. Sequencing of both PCR products showed a marked dissimilarity in nucleotide sequence in the clonally unique VDJ joint region, providing strong evidence for the separate cellular genesis of each lymphoma. These results suggest that late relapses of Burkitt's lymphoma should be examined for clonal distinctiveness. If the second lymphoma is distinct from the primary one, it might be treated as a primary lymphoma rather than as recurrent disease.

Lymphoproliferative disorder involving the cervix in a patient being treated with FK-506

FK-506 is an immunosuppressive agent used mainly to prevent allograft rejection in organ transplant patients. Recently, it has been applied as a treatment for patients with autoimmune disorders. An entity called posttransplant lymphoproliferative disorder (PTLD) is a well-recognized result of immunosuppression in transplant patients receiving long-term immunosuppression. This disorder is a complication of treatment with FK-506 in 0.7 to 1.6% of transplant patients and is usually of B-cell origin. A majority of patients have serologic evidence of EBV infection. We report a case of a patient receiving long-term FK-506 therapy for multiple sclerosis who developed lymphoproliferative disorder involving the cervix. We will discuss the possible role of FK-506 initiation of this tumor.

Evaluation of monoclonal antibody-mediated anti-acute myeloid leukemia immunotherapy in a SCID/hu model

The therapeutic potential of the IgM complement-fixing murine monoclonal antibody (mAb) PM-81 (anti-CD15) against acute myeloid leukemia (AML) was assessed in a SCID/hu leukemia model. Intraperitoneal (i.p.) injection of NB4 leukemia cells resulted in aggressive growth of leukemia cells in the peritoneal cavity of irradiated SCID/CB-17 mice. Flow cytometric analysis of human CD15, 33 and 45 expression, as well as cytologic examination, revealed that leukemia cells disseminated into the peripheral blood and multiple tissues of the mice. The approximately linear relationship between the injected leukemia cells and the subsequent leukemia cell proliferation provided a reliable model for monitoring the therapeutic effects of immunotherapy. Intraperitoneal injection of the mAb PM-81 markedly suppressed leukemia cell growth in this SCID/leukemia model. Most of the untreated mice died within 35-50 days of leukemia cell inoculation. Four weeks after inoculation of NB4 cells, five of nine mAb PM-81 treated mice had no solid tumor growth and six of nine had no detectable peritoneal exudate leukemia cells as determined by flow cytometry. In contrast, 100% of the mice in the untreated or control mAb groups were found to have both solid and peritoneal leukemia growth. In further experiments designed to evaluate the effects of therapy on survival, 50% (4/8) of PM-81 treated mice survived to 150 days, and had no detectable solid or suspension leukemia cells detectable at necropsy. In contrast, the median survival of untreated or negative control antibody-treated mice was 40 days (comparison to PM-81 treated; p = 0.006 and p = 0.03, respectively). The mechanism of leukemia cell suppression is not likely due to complement fixation since we could not demonstrate in vitro any cytotoxicity mediated by SCID mouse plasma. Further study is required to understand the mechanism of the antileukemia effect of PM-81 in this model.

The morphologic spectrum of non-Hodgkin's lymphomas with BCL1/cyclin D1 gene rearrangements

BCL1/PRAD1 gene rearrangements involving the cyclin D1 gene are a feature of about 70% of centrocytic/mantle-cell lymphomas (CC/MCL) but are identified in only a small proportion of other B-cell non-Hodgkin's lymphomas. Of 37 lymphomas found to have BCL1/cyclin D1 (PRAD1, CCND1) gene rearrangements, 30 fit the morphologic and immunophenotypic criteria for typical CC/MCL. Seven cases with morphologic features atypical for CC/MCL were identified. CD5+ monoclonal B cells were documented in all these cases. Six cases were subsequently stained for cyclin D1 protein, and all showed nuclear positivity. Five cases had variably sized foci of cells with moderately abundant pale cytoplasm resembling parafollicular/monocytoid B cells, marginal zone cells, hairy cells, or even proliferation centers. Transformed-appearing cells were also present in some lymphomas. In one case, striking follicular colonization created a markedly nodular growth pattern mimicking a follicular lymphoma. A sixth case had a marked predominance of small, round lymphocytes at some sites, mimicking a small lymphocytic lymphoma. Five of these six cases also had areas more typical of CC/MCL. The seventh case was a CD5-positive splenic marginal zone-like lymphoma (SMZL) with plasmacytic differentiation and circulating villous lymphocytes consistent with a splenic lymphoma with villous lymphocytes (SLVL). These cases illustrate the morphologic spectrum of small B-cell lymphoid neoplasms that have BCL1/cyclin D1 gene rearrangements and overexpression of cyclin D1. Despite the BCL1 translocation and cyclin D1 overexpression, the splenic lymphoma with plasmacytic differentiation was definitely not a CC/MCL and fit the clinicopathologic entity of SMZL/SLVL. The other six cases are best considered CC/MCL variants based on a combined morphologic, immunophenotypic, and genotypic evaluation. Genotypic or immunophenotypic studies to identify cyclin D1 rearrangements and overexpression, although not pathognomonic, are useful in recognizing these variant CC/MCL cases, which can mimic almost any of the other well-described but more indolent low-grade B-cell lymphomas and leukemias. Some of the variant CC/MCL cases had features in common with the CD5+ cyclin D1+ SMZL/SLVL, suggesting a possible relationship between these two otherwise distinct entities.

Recurrent Epstein-Barr virus-associated lesions in organ transplant recipients

Posttransplant lymphoproliferative disorders (PTLD) are related to Epstein-Barr virus (EBV) and range from lymphoid hyperplasias to lymphomas. The authors report 11 transplant recipients with recurrent EBV-associated lesions. Four patients presented with EBV-positive mononucleosis-like lymphadenitis. One had recurrence of a similar lesion and the other three developed polymorphic PTLDs. Matched clonal studies in one patient showed clonal lymphoid and EB viral populations in the recurrent lesion, but not in the initial lesion. Six patients presented with polymorphic PTLDs. Five later developed histologically dissimilar tumors that resembled non-Hodgkin's lymphoma (two B-cell and one T-cell origin), Hodgkin's disease (one patient), or smooth muscle tumor (one patient). Matched clonal studies were available from one patient and showed that the primary and recurrent lesions were clonally distinct. The sixth patient had recurrence of histologically and clonally identical polymorphic PTLD. One patient presented with monomorphic PTLD and developed recurrence of a clonally identical tumor after a 6-month remission. This study shows that a few patients with EBV-associated lesions have clinical recurrence, which may be either a relapse of the original process or a new EBV-associated lesion. In some patients, the new lesion appeared to represent a more fully developed malignancy that did the antecedent lesion.

CD43 and CD5 antibodies define four normal and neoplastic B-cell subsets: a three-color flow cytometric study

CD43 antibodies are best known for identifying normal and neoplastic T cells and a subset of neoplastic B cells in paraffin sections. The frequency of nonneoplastic CD43 + B cells in different reactive settings, the proportion of B-cell neoplasms with small CD43+ populations, and the relationship of CD43+ B cells was therefore studied in 138 specimens using three-color cytometric analysis. CD43 and CD5 defined four normal B-cell subsets (CD43 + CD5 +, CD43 + CD5-, CD43 - CD5+, and CD43-CD5-). A significantly greater proportion of CD43+ B cells was found in cord blood and putative HIV+ blood samples than in normal control bloods. B-cell neoplasms derived from each of these four B-cell subsets were identified, with CD43+ /CD5+ and CD43-/CD5- neoplasms being most common. The predominant B-cell population coexpressed CD43 alone in 2/39 neoplasms and CD5 alone in four. A minority of cases showed heterogeneous CD43 expression. The B cells in two of three posttransplant lymphoproliferative disorders coexpressed CD43. B cells showed weaker CD43 staining than did T-cells (relative fluorescence 0.38 +/- 0.29). These findings support the concept that CD43 expression by neoplastic B cells is not an aberrant finding. CD43 expression on normal and neoplastic B cells is independent of CD5 expression even though CD43 and CD5 are frequently coexpressed. CD43 expression by B cells sometimes might be underestimated in paraffin sections because it is much weaker than on T cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of cyclin D1 protein in centrocytic/mantle cell lymphomas with and without rearrangement of the BCL1/cyclin D1 gene

Centrocytic/mantle cell lymphoma (CC/MCL) is a morphologically defined B-cell non-Hodgkin's lymphoma characterized by a distinctive immunophenotype, BCL1/cyclin D1 (PRAD1) gene rearrangements, and, most recently, by overexpression of cyclin D1. Even using multiple breakpoint probes for BCL1 (MTC, p94PS) and cyclin D1, however, only approximately 70% of CC/MCL have a rearrangement consistent with a t(11;14) (q13;q32). To determine whether the type of molecular translocation affects the degree of cyclin D1 expression and to evaluate lymphomas diagnosed as CC/MCL but lacking molecular evidence of a BCL1 or cyclin D1 translocation, 16 CC/MCL and four cases of small lymphocytic lymphoma/B-CL1 (SLL/B-CLL) were stained using an anti-cyclin D1 antibody. All cases with a cyclin D1 translocation detected by Southern blotting techniques as well as four of the five CC/MCL without a documentable translocation showed nuclear cyclin D1 protein expression. There was no apparent correlation between staining intensity and the precise site or presence of a detectable translocation. Cases with a mantle zone growth pattern showed infiltration of the cyclin D1 positive cells into reactive follicular centers. None of the four SLL/B-CLL showed cyclin D1 expression. These findings show overexpression of the cyclin D1 protein in virtually all CC/MCL independent of the type or presence of a documentable BCL1 or cyclin D1 molecular rearrangement. The mechanism for cyclin D1 overexpression in the cases without a documentable rearrangement and the relationship of cyclin D1 overexpression to the pathogenesis of mantle cell neoplasia remain uncertain.

Extramedullary plasmacytoma of the head and neck: use of paraffin sections to assess clonality with in situ hybridization, growth fraction, and the presence of Epstein-Barr virus

The diagnosis of extramedullary plasmacytomas (EMP) is usually easy to conform with immunohistochemical stains for kappa and lambda. In some cases, however, immunostains are problematic. In addition, prognostic features are not well described nor is it known whether EMP are associated with the Epstein-Barr virus. Therefore, 23 EMP of the head and neck (from 20 patients) were studied to (1) compare a non-isotopic paraffin section in situ hybridization technique for kappa and lambda mRNA with standard immunohistochemical techniques for assessing light chain expression, (2) compare the histologic grade to the proliferative fraction using an antibody for the proliferating cell nuclear antigen, and (3) determine the frequency of Epstein-Barr virus (EBV) association using probes for the EBV DNA (EBV NOT 1) and RNA (EBER-1). Light chain class restriction was demonstrated in 22/23 biopsies by in situ hybridization and in 21/23 biopsies by standard immunohistochemical techniques. Five of the six biopsies of well-differentiated EMP had proliferating cell nuclear antigen scores of 0 to 10% positive cells and one had 11 to 25% positive cells compared with greater than 75% in the one poorly differentiated EMP. Of 15 moderately differentiated EMP, 10 had proliferating cell nuclear antigen scores of 11 to 75%, and 5 had scores of greater than 75%. EBV DNA was detected in 1/23 biopsies and EBV RNA in 4/23 biopsies (3 patients). Thus, non-isotopic in situ hybridization is a useful technique to document clonality of plasma cells in routinely fixed, paraffin-embedded sections. Unlike routine immunohistochemistry, in situ hybridization avoids the problem of detecting stromal or nonspecific uptake of immunoglobulin.(ABSTRACT TRUNCATED AT 250 WORDS)

In situ hybridization detection of cyclin D1 mRNA in centrocytic/mantle cell lymphoma

BACKGROUND

Centrocytic/mantle cell lymphoma (MCL) is characterized by a specific chromosomal translocation, t(11;14)(q13;q32), which leads to deregulated expression of the G1 cyclin, cyclin D1 (PRAD1, CCND1, BCL1). Cyclin D1 overexpression has been demonstrated in MCL at the mRNA level by Northern blotting and at the protein level by both Western blotting and immunoperoxidase staining.

PATIENTS AND METHODS

To assess the utility of in situ hybridization (ISH) to detect cyclin D1 mRNA expression in formalin-fixed, paraffin embedded tissue, five MCL specimens from three patients and two cases of B-cell small lymphocytic lymphoma (B-SLL) were studied. BCL1 major translocation cluster gene rearrangements had been previously documented in two MCL patients; the other MCL and the two B-SLL, showed no detectable BCL1 or cyclin D1 rearrangements.

RESULTS

ISH was performed using anti-sense 3H-labeled RNA probes for the cyclin D1 3' untranslated region (pPL7) and partial cyclin D1 cDNA (pPL8). ISH experiments using an anti-sense actin RNA probe demonstrated adequate RNA preservation in all cases. Each of five specimens of MCL demonstrated increased cyclin D1 mRNA. In contrast, neither of the two cases of B-SLL demonstrated detectable levels.

CONCLUSIONS

Overexpression of cyclin D1 mRNA can be detected in MCL by ISH using formalin fixed paraffin embedded tissue. The ISH technique may be useful in diagnosing and classifying low-grade B-cell lymphomas and should be applicable to the study of cyclin D1 mRNA expression in a broad spectrum of lymphoid proliferations and solid tumors.

CD8-positive B-cell chronic lymphocytic leukemia. A report of two cases

Most B-cell chronic lymphocytic leukemias and a small normal subset of B lymphocytes express the T-cell-associated CD5 antigen; expression of other T-cell antigens has been reported only rarely. The authors report two cases of typical B-cell chronic lymphocytic leukemia, seen during 1 year, in which two-color flow cytometric analysis documented expression of the T-cell-associated CD8 antigen by the monoclonal B cells. Genotypic studies showing immunoglobulin but not T-cell-receptor gene rearrangements confirmed the B-cell origin of the neoplastic cells. The true frequency of the CD8-positive B-cell chronic lymphocytic leukemia, any clinical implications, and the possibility of a normal subset of CD5-positive CD8-positive B cells remain to be determined.