Body cavity lymphoma

Serous fluids and hematolymphoid disorders

Diagnosing hematolymphoid neoplasm by evaluating fine-needle aspiration (FNA) cytology sample is controversial and requires experience and clinical skills. This concept becomes more challenging when evaluating hematolymphoid neoplasm in body fluid. Differentiating between low-grade lymphoma and reactive lymphocytes is often difficult by morphology alone as reactive lymphoid cells may acquire activation morphology from being exposed to different cytokines within the body fluid. However, in most cases there are specific features that may aid in differentiating small reactive from non-reactive lymphocytes including the round shape of the nucleus, the absence of visible nucleoli and the presence of fine clumped chromatin. In large cell lymphoma and leukemia cells involvement of body fluid this concept becomes less challenging. Large cell lymphoma and leukemia cells tend to have large size nuclei, less mature chromatin, and visible nucleoli with and without cytoplasmic vacuoles. However, to reach accurate diagnosis and subclassification, the utilizing of flow cytometry, to confirm monoclonality, and other ancillary studies such immunocytochemistry, cytogenetics and molecular studies is needed. This review article will be incorporated finally as one of the chapters in CMAS (CytoJournal Monograph/Atlas Series) #2. It is modified slightly from the chapter by the initial authors in the first edition of Diagnostic Cytopathology of Serous Fluids.

Serous cavity metastasis: Evaluation of unknown primary

Malignant effusions can occur in patients with neoplasia. Once a metastatic diagnosis is confirmed, the primary site of origin of malignancy needs to be ascertained. This task can be challenging without a prior history of malignancy. In some patients their effusion may be the initial presentation of an underlying malignancy. Metastases usually present with a dual population of mesothelial and malignant cells. Combining cytomorphologic examination with ancillary testing such as immunocytochemistry can help identify the origin of the foreign malignant cell population. Helpful architectural clues include a single cell pattern, solid cell ball pattern, single file arrangement, papillary formation, psammoma bodies and background mucin. Useful cellular features include the presence of signet ring cells, small cells, pleomorphic and multinucleated giant cells, squamous cells, spindle cells and pigmentation. Rarely, despite an extensive work-up the primary site of origin for a malignant effusion may remain unresolved. This review article will be incorporated finally as one of the chapters in CMAS (CytoJournal Monograph/Atlas Series) #2. It is modified slightly from the chapter by the initial authors in the first edition of Cytopathologic Diagnosis of Serous Fluids.

Pleural effusion related to IgG4

Purpose of review

The causes of exudative pleural effusions are diverse and frequently remain unclear despite exhaustive examinations. Recently recognized IgG4-related disease (IgG4-RD) is a fibroinflammatory disorder that can affect nearly any organ including the lungs. This review will focus on the involvement of IgG4 in exudative pleural effusion of unknown cause.

Recent findings

IgG4 is found to be involved in a proportion of patients with undiagnosed pleural effusions. Pleural involvement in IgG4-RD can be seen in isolation or association with other organ disease. Pleural thickening and/or effusion are common clinical features of IgG4-related pleural lesions, and this condition is histologically characterized by a lymphoplasmacytic infiltrate enriched in IgG4-positive plasma cells in the pleura. Although the pathogenesis of IgG4-RD is poorly understood, there is a growing body of evidence that indicates an antigen-driven process requiring T-cell and B-cell interaction in which autoantibodies, plasmablasts, follicular helper T cells and CD4+ cytotoxic T lymphocytes participate.

Summary

The possibility of IgG4-related pleural lesion should be considered in patients with pleural effusion of unexplained cause when lymphoplasmacytic infiltration is seen in a pleural biopsy specimen. This condition is responsive to systemic steroid therapy.

Crosstalk between the mesothelium and lymphomatous cells: insight into the mechanisms involved in the progression of body cavity lymphomas

The peculiar localization of body cavity lymphomas implies a specific contribution of the intracavitary microenvironment to the pathogenesis of these tumors. In this study, primary effusion lymphoma (PEL) was used as a model of body cavity lymphoma to investigate the role of mesothelial cells, which line the serous cavities, in lymphoma progression. The crosstalk between mesothelial and lymphomatous cells was studied in cocultures of primary human mesothelial cells (HMC) with PEL cells and a xenograft mouse model of peritoneal PEL. PEL cells were found to induce type 2 epithelial–mesenchymal transition (EMT) in HMC, which converted into a myofibroblastic phenotype characterized by loss of epithelial markers (pan cytokeratin and E-cadherin), expression of EMT-associated transcriptional repressors (Snail1, Slug, Zeb1, Sip1), and acquisition of α-smooth muscle actin (α-SMA), a mesenchymal protein. A progressive thickening of serosal membranes was observed in vivo, accompanied by loss of cytokeratin staining and appearance of α-SMA-expressing cells, confirming that fibrosis occurred during intracavitary PEL development. On the other hand, HMC were found to modulate PEL cell turnover in vitro, increasing their resistance to apoptosis and proliferation. This supportive activity on PEL cells was retained after transdifferentiation, and was impaired by interferon-α₂b treatment. On the whole, our results indicate that PEL cells induce type 2 EMT in HMC, which support PEL cell growth and survival, providing a milieu favorable to lymphoma progression. Our findings provide new clues into the mechanisms involved in lymphoma progression and may indicate new targets for effective treatment of malignant effusions growing in body cavities.

Herpesvirus-Associated B-cell Proliferations

This article reviews the spectrum of Epstein-Barr virus and Kaposi sarcoma herpesvirus (KSHV/HHV-8)-associated B-cell lymphoid proliferations, their pathologic features and clinical presentation, diagnostic criteria, and pathogenetic aspects. Emphasis is on the differential diagnosis issues and difficulties that the pathologist may face for the correct identification and interpretation of these lesions.

The M type K15 protein of Kaposi's sarcoma-associated herpesvirus regulates microRNA expression via its SH2-binding motif to induce cell migration and invasion

Kaposi's sarcoma (KS) associated herpesvirus (KSHV) is the etiological agent of KS. In vivo, KS is a tumor capable of spreading throughout the body, and pulmonary metastasis is observed clinically. In vitro, KSHV induces the invasiveness of endothelial cells. The KSHV open reading frame K15 is a KSHV-specific gene encoding a transmembrane protein. Two highly divergent forms of K15, the predominant (P) and minor (M) forms (K15P and K15M, respectively), have been identified in different KSHV strains. The two K15 alleles resemble the latent membrane protein 2A (LMP2A) gene of Epstein-Barr virus (EBV) in their genomic locations and protein topology. Also, both K15 proteins have motifs similar to those found in the EBV LMP1 protein. K15 therefore appears to be a hybrid of a distant evolutionary relative of EBV LMP1 and LMP2A. Since both LMP1 and LMP2A proteins are capable of inducing cell motility, we sought to determine whether K15 has similar abilities. In this study, we show that K15M is latently expressed in KSHV-positive PEL cells and knockdown of K15M in PEL cells reduces cell motility. K15M localizes to lysosomal membranes and induces cell migration, invasion, and NF-kappaB (but not AP-1) activity via its conserved SH2-binding motif. K15M also induces the expression of microRNAs miR-21 and miR-31 via this conserved motif, and knocking down both these microRNAs eliminates K15M-induced cell motility. Therefore, K15M may contribute to KSHV-mediated tumor metastasis and angiogenesis via regulation of miR-21 and miR-31, which we show here for the first time to be a specific regulator of cell migration. In light of these findings, the targeting of K15 or the downstream microRNAs regulated by it may represent novel therapies for treatment of KSHV-associated neoplasia.

Primary effusion lymphoma: a series of 4 cases and review of the literature with emphasis on cytomorphologic and immunocytochemical differential diagnosis

BACKGROUND

Primary effusion lymphoma (PEL) is a human herpes virus-8 (HHV-8)-associated and very rare type of lymphoma usually confined to the body cavities and commonly observed in human immunodeficiency virus (HIV)-infected patients. A comparison was made between the cytologic and immunocytochemical features of 4 cases of PEL encountered in the authors' department with those reported to date in the literature.

METHODS

A comprehensive comparison of the cytologic and immunocytochemical features of the 4 cases with those reported in the literature was conducted.

RESULTS

Cytologically, the most consistent features of the 4 cases and those in the literature included large cell size, moderate to abundant cytoplasm, a single nucleus in most cells with occasional bi- or multinucleated giant cells, single to multiple prominent nucleoli, and coarse chromatin. Immunocytochemically, only 2 (50%) of the current cases were of the null-phenotype compared with 93% of cases in the literature; the other 2 cases had a T-cell phenotype. Activation markers were expressed in 50% and 78% of the current cases and the literature cases, respectively. Positivity for HHV-8 was proven in the 4 cases by immunocytochemistry.

CONCLUSIONS

Cytomorphologically, PEL exhibits features bridging large cell immunoblastic and anaplastic large cell lymphoma. Although it is usually of null-phenotype, it may occasionally express B-cell or T-cell markers, rendering its distinction difficult from other lymphomatous effusions on a cytologic and immunocytochemical basis alone. Therefore, HHV-8 detection is an essential confirmatory ancillary test in suspected cases of PEL.

Primary Effusion Lymphoma Involving both Pleural and Abdominal Cavities in a Patient with Hepatitis B Virus-related Liver Cirrhosis

Primary effusion lymphoma (PEL) is an unusual form of non-Hodgkin's lymphoma, which is characterized by lymphomatous effusion in body cavities, but no associated mass lesions. It is usually associated with an immunodeficient state most often with the human immunodeficiency virus (HIV). We describe a 54-year-old man with HIV-negative PEL, with a history of hepatitis B virus-related liver cirrhosis. Both abdominal and pleural cavities were involved; no solid tumor masses were found and bone marrow investigations were normal. The ascites and pleural effusion contained numerous pleomorphic lymphoid cells. Immunophenotyping was positive for CD138. Chromosome study showed complex cytogenetics. The genomic human herpesvirus-8 was detected in the lymphoma cells. It is postulated that the immunosuppressed state in this patient may have been caused by cirrhosis. The patient received four cycles of chemotherapy of CHOP and Picibanil (OK-432) intraperitoneal administration. However, no durable remission was achieved. Adefovir failed to halt the progressive liver failure after the development of YMDD mutant related to lamivudine. He died of sepsis and hepatic failure.

The Undiagnosed Pleural Effusion

The most common causes for undiagnosed transudative effusions are congestive heart failure and hepatic hydrothorax. Pleural fluid N terminal pro-brain natriuretic peptide levels higher than 1500 pg/mL are virtually diagnostic of congestive heart failure. The most common causes for undiagnosed exudative pleural effusions are malignancy, pulmonary embolism, and tuberculosis. Clinical characteristics of patients with a malignant pleural effusion are symptoms for more than 1 month, absence of fever, blood-tinged pleural fluid, and CT findings suggestive of malignancy. Thoracoscopy is useful to establish the diagnosis of malignancy and tuberculosis.

Subtype C1 persistent infection of HHV-8 in a PEL patient

PEL, a rare type of lymphoma constituting less than 5% of NHLs, has been recently identified as a distinct clinical and pathological entity among the B-cell lymphomas, with characteristic morphologic, immunophenotypic, molecular and viral features. ICC, PCR, RT-PCR and sequencing were carried out in biologicals samples from a 44-year-old, non-smoker Caucasian male patient of Greek nationality, HIV-1 negative and HCV positive. The ICC results showed CD30 + , Vimentin + , EMA + , Ki67 + , Pankeratin- and negative to B and T antibodies. In addition, HHV-8 was detected in pleural fluid. Examination of blood samples of the patient over a period of nearly two years showed a persistent infection of HHV-8. Phylogenetic analysis revealed a close relation to the C1 variant of HHV-8. The samples was also found EBV negative by PCR. Using a combination of clinical, morphological, immunohistochemical features and molecular biology techniques in this study we document a PEL case with persistent HHV-8 of genotype C1 infection.

Patterned CpG methylation of silenced B cell gene promoters in classical Hodgkin lymphoma-derived and primary effusion lymphoma cell lines

Hodgkin and Reed-Sternberg (HRS) cells of classical Hodgkin lymphoma (cHL) and primary effusion lymphoma (PEL) are derived from germinal center (GC) and post-GC B cells, respectively. Neither express many of the B cell genes or surface markers typically expressed by other GC-derived B cell lymphomas or normal B cells. This loss of B cell gene expression is not due to a lack of essential transcription factors, as studies have shown that the ectopic expression of missing transcription factors failed to reactivate endogenous target genes. These results implicate epigenetic mechanisms extinguishing B cell gene expression. Silenced endogenous B cell genes representing a surface receptor, B29 (Igbeta, CD79b), a signaling molecule, TCL1, and a transcription factor, Bob1 (OCA-B, OBF-1), were reactivated by 5-aza-2'-deoxycytidine, indicating that gene silencing in HRS and PEL cells is due to DNA methylation. Genomic bisulfite sequencing corroborated this prediction and revealed three distinct patterns of methylation for the silenced B29 and TCL1 promoters. These distinct patterns consisted of 5' promoter CpG methylation alone, 5' and 3' promoter CpG methylation sparing sites in the central cores, and complete CpG methylation throughout the promoter regions. The silenced Bob1 promoter showed one pattern of dense CpG methylation at essentially all sites. These consistent patterns predict that, although gene silencing in many HRS and PEL cells mimics appropriate gene silencing, in some cases of complete CpG methylation throughout entire promoters both the activation and targeting of methylation is abnormal.

Natural killer cell-type body cavity lymphoma following chronic active Epstein-Barr virus infection

We describe a 69-year-old female who developed natural killer cell-type body cavity lymphoma following chronic active Epstein-Barr virus (CAEBV) infection. Examination of the patient's pleural effusion revealed large abnormal lymphocytes, which were CD2(+), CD7(+), CD30(+), CD56(+), CD3(-), and CD4(-). No rearrangement of T cell receptor genes was detected. Clonal proliferation of Epstein-Barr virus (EBV)-infected cells in pleural effusion was demonstrated by Southern blot hybridization analysis. Human herpesvirus type-8 (HHV-8) DNA was not detected in these cells. The patient achieved a complete remission with combination chemotherapy. Prior to the clinical onset of lymphoma, high fever of unknown origin had persisted for 21 months. IgG antibodies to EBV-viral capsid antigen and to EBV-early antigens, types D and R were not high (1:160 and less than 1:10, respectively). Two months after the onset of fever, however, retrospective quantitative PCR assay revealed a high EBV DNA load in plasma, indicating that CAEBV infection had been the cause of the patient's recurrent fever. The remarkable features of this case are (i) the development of lymphoma following CAEBV infection that demonstrated a normal pattern of EBV-specific antibodies, (ii) the development of HHV-8-negative body cavity lymphoma, and (iii) the effectiveness of combination chemotherapy.

Biological aspects of Epstein-Barr virus (EBV)-infected lymphocytes in chronic active EBV infection and associated malignancies

Most primary Epstein-Barr virus (EBV) infections are clinically inapparent, but occasionally EBV infection can cause acute infectious mononucleosis. EBV has been linked to a variety of hematologic and non-hematologic malignancies. Chronic active EBV (CAEBV) infection designates a recently identified EBV-associated syndrome characterized by a variety of serious hematological disorders, including malignant lymphoma. EBV was found to infect circulating T- and/or NK-cells in patients with CAEBV infection. These EBV-infected T- and/or NK-cells express EBNA-1, LMP-1, and LMP-2A, a type II form of EBV latency, which is also observed in nasopharyngeal carcinoma (NPC), Hodgkin's disease (HD), and peripheral T-cell lymphoma. CAEBV infections may thus represent a subset of EBV-associated T- and/or NK-cell lymphoproliferative disorders.