Prominent intrasinusoidal infiltration of the bone marrow by mantle cell lymphoma

Mantle cell lymphoma

MCL is a well-characterized generally aggressive lymphoma with a poor prognosis. However, patients with a more indolent disease have been reported in whom the initiation of therapy can be delayed without any consequence for the survival. In 2017 the World Health Organization updated the classification of MCL describing two main subtypes with specific molecular characteristics and clinical features, classical and indolent leukaemic nonnodal MCL. Recent research results suggested an improving outcome of this neoplasm. The addition of rituximab to conventional chemotherapy has increased overall response rates, but it did not improve overall survival compared to chemotherapy alone. The use of intensive frontline therapies including rituximab and consolidation with autologous stem cell transplantation ameliorated response rate and prolonged progression-free survival in young fit patients, but any impact on survival remains to be proven. Furthermore, the optimal timing, cytoreductive regimen and conditioning regimen, and the clinical implications of achieving a disease remission even at molecular level remain to be elucidated. The development of targeted therapies as the consequence of better understanding of pathogenetic pathways in MCL might improve the outcome of conventional chemotherapy and spare the toxicity of intense therapy in most patients. Cases not eligible for intensive regimens, may be considered for less demanding therapies, such as the combination of rituximab either with CHOP or with purine analogues, or bendamustine. Allogeneic SCT can be an effective option for relapsed disease in patients who are fit enough and have a compatible donor. Maintenance rituximab may be considered after response to immunochemotherapy as the first-line strategy in a wide range of patients. Finally, since the optimal approach to the management of MCL is still evolving, it is critical that these patients are enrolled in clinical trials to identify the better treatment options.

MYD88 L265P somatic mutation: its usefulness in the differential diagnosis of bone marrow involvement by B-cell lymphoproliferative disorders

OBJECTIVES

To examine the usefulness of the MYD88 L265P somatic mutation in identifying cases of lymphoplasmacytic lymphoma (LPL) from other lymphoplasmacytic neoplasms in bone marrow biopsy specimens.

METHODS

We studied 64 bone marrow biopsy specimens with involvement by various small B-cell lymphomas or plasma cell myeloma.

RESULTS

The MYD88 L265P somatic mutation was present in 13/13 cases of LPL, 1/13 cases of hairy cell leukemia, and absent in the other mature B-cell neoplasms tested. A test set of diagnostically challenging bone marrow cases with lymphoplasmacytoid morphology (B-cell lymphoma, not otherwise specified) was selected for additional review and reclassified, without knowledge of the MYD88 L265P status. Of those 16 cases, 7 were positive for MYD88, including 4/4 cases that were reclassified as LPL during the review.

CONCLUSIONS

Although not entirely specific, MYD88 L265P is a useful adjunct for bone marrow diagnosis in separating LPL from other small B-cell lymphomas and plasma cell myeloma.

Mantle cell lymphoma

MCL is a well-characterized clinically aggressive lymphoma with a poor prognosis. Recent research findings have slightly improved the outcome of this neoplasm. The addition of rituximab to conventional chemotherapy has increased overall response rates, but it does not improve overall survival with respect to chemotherapy alone. The use of intensive frontline therapies including rituximab and consolidated by ASCT ameliorates response rate and prolongs progression-free survival, but any impact on survival remains to be proven. Furthermore, the optimal timing, cytoreductive regimen and conditioning regimen, and the clinical implications of achieving a disease remission even at molecular level remain to be elucidated. The development of targeted therapies as the consequence of better dissection of pathogenetic pathways in MCL might improve the outcome of conventional chemotherapy in most patients and spare the toxicity of intense therapy in a minority of MCL patients characterized by a relatively indolent disease. Patients not eligible for intensive regimens, such as hyperC-VAD, may be considered for less demanding therapies, such as the combination of rituximab either with CHOP or with purine analogues, or bendamustine. Allogeneic SCT can be an effective option for relapsed disease in patients who are fit enough and have a compatible donor. Maintenance rituximab may be considered after response to immunochemotherapy for relapsed disease, although there are currently no data to recommend this approach as the first-line strategy. As the optimal approach to the management of MCL is still evolving, it is critical that these patients be enrolled in clinical trials to identify better treatment options.

Splenic marginal zone lymphoma--a clinicopathological study in a series of 16 patients

Splenic marginal zone lymphoma (SMZL), characterized in the WHO classification of lymphoid tumors, is a rare disorder comprising less than 1% of lymphoid neoplasms; only a few series concerning this entity have been published. Although this type of lymphoma is well defined histologically, its histogenesis remains obscure. Moreover, specific biological markers are still lacking and immunophenotype profile is not specific. These and other reasons, such as the existence of cytogenetic subtypes, have led to some authors to suspect that SMZL constitutes a heterogeneous entity. We have analyzed a series of sixteen SMZL cases from four hospitals in our community, from a clinical, biological and pathological point of view. When compared with those reported in the literature, our findings show three main differences: our patients less frequently showed an intrasinusoidal bone marrow infiltration pattern; the presence of a serum monoclonal component was rarely seen; and CD5-positive SMZL cases appear to be more common than previously thought.

Intrasinusoidal bone marrow infiltration and splenic marginal zone lymphoma: a quantitative study

Intrasinusoidal infiltration (ISI) is a pattern of invasion that is rarely found on bone marrow (BM) biopsies, and is considered as a hallmark of splenic marginal zone cell lymphoma (SMZL). We analysed BM biopsies showing intrasinusoidal infiltration from 54 consecutive patients with different types of lymphoma to verify if ISI quantity was a diagnostic criterion for SMZL. There were 35 primary splenic lymphoma (PSL) and 19 non-PSL; 28 SMZL, three non-splenic MZL, six mantle cell, six small lymphocytic, four follicular, four diffuse large B cell, one peripheral T cell, one lymphoplasmacytic and one anaplastic large-cell lymphoma. The quantity of BM infiltrate was assessed on CD45, CD20 and CD3 stained sections. The mean percentage of total (TI) and intrasinusoidal (ISI) lymphocytes was calculated in 10 areas for each case. TI quantity was 21.57 in PSL and 35.05 in non-PSL (P = 0.04). ISI quantity was 5.23 in PSL and 7.62 in non-PSL (P = 0.08), 5.83 in SMZL and 2.83 in other types of PSL (P = 0.12), 4.46 in non-splenic MZL and 8.21 in other types of non-PSL (P = 0.28). No difference in ISI quantity was found among the lymphoma subtypes, either in PSL (P = 0.74) or non-PSL (P = 0.3). The data demonstrate that ISI quantity in BM biopsies is not a reliable diagnostic parameter for SMZL.

Bone Marrow Biopsy Involvement by Non-Hodgkin's Lymphoma

To evaluate the features of bone trephine biopsy involvement by non-Hodgkin lymphoma, 450 specimens were evaluated for percentage of marrow involvement, pattern of involvement, presence of germinal centers or follicular structures, and discordance with other involved sites. A subset of 197 cases was evaluated for evidence of concurrent peripheral blood involvement. Follicular grade 1 lymphoma (30.4%) was the most common type to involve the marrow, followed by diffuse large B-cell lymphoma (16.0%), mantle cell lymphoma (9.3%), low-grade B-cell lymphoma, not otherwise specified (8.7%), lymphoplasmacytic lymphoma (8.4%), follicular grade 2 lymphoma (7.1%), and mature T- and NK-cell lymphomas (6.4%). A mixed pattern of infiltration was most common, followed by paratrabecular, nodular, diffuse, and interstitial patterns. Greater than 90% of follicular lymphomas had at least a focal paratrabecular infiltration pattern, but this pattern was also seen with other lymphoma types. Interstitial disease infiltration tended to correlate with lymphoplasmacytic lymphoma but was also not specific. The presence of germinal centers or follicular structures was associated with follicular lymphoma in 88% of cases. Discordance between the bone marrow morphology and other tissue sites was observed in 24.9% of cases and was most often seen with follicular or diffuse large B-cell lymphoma. Peripheral blood involvement by lymphoma was observed in 29% of cases, found in all disease groups except for follicular grade 3 lymphoma. This study highlights the frequency of different lymphoma patterns in the marrow, limitations of primary lymphoma classification on biopsy material alone, and the relative frequency of marrow discordance and peripheral blood involvement by marrow lymphoma.

Mantle cell lymphoma

PURPOSE OF REVIEW

Mantle cell lymphoma is the B-cell lymphoma with the worst prognosis. Until now, no standard treatment has resulted in cure. Improvements in understanding of the disease are needed to advance therapeutic efforts.

RECENT FINDINGS

Pathology and immunohistochemistry can identify the subset of patients with the worse prognosis. New data suggest that at least a subset of mantle cell lymphoma cases have undergone some form of antigene selection, and particular types of Ig gene rearrangement seem to give a better prognosis. The cell cycle, the ATM, gene and the nuclear factor kappaB pathways are the main targets of the genetic abnormalities occurring in mantle cell lymphoma: new genomic and expression data have been recently published. Unfortunately, this progress has not yet brought any major improvements in therapeutic approaches, which still remain highly unsatisfactory. Autologous and allogenic bone marrow transplantations appear to be the only current treatments that might improve the outcome of patients with PMCL. New additional treatment modalities are currently under investigation.

SUMMARY

This review summarizes all the most recent data published on the biology and treatment of mantle cell lymphoma.