Lauren C Pinter-Brown, MD
Given the patient's presentation of generalized lymphadenopathy, B symptoms, fatigue (probably from anemia), hepatosplenomegaly, immunophenotyping results of flow cell cytometry, and central nervous system (CNS) involvement, blastoid mantle cell lymphoma (MCL) is the most likely diagnosis. Although small lymphocytic lymphoma (SLL)/chronic lymphocytic leukemia (CLL) and diffuse large B-cell lymphoma (DLBCL) most often occur in men 60-70 years old with similar clinical findings, an initial presentation with a stage IV involvement is rare; moreover, SLL/CLL and DLBCL are typically CD23 positive. Pleomorphic MCL displays larger and more pleomorphic cells with irregular nuclei, prominent nucleoli, and pale cytoplasm, resembling DLBCL.
MCL is a rare type of mature B-cell lymphoma that was first described in 1992 and was recognized by World Health Organization in 2001. MCL represents 3%-10% of all non-Hodgkin lymphoma cases, with an incidence between 0.50 and 1.0 per 100,000 population. Men are more likely than women to present with MCL by a ratio of 3:1, with a median age at presentation of 67 years. Clinical presentation includes advanced disease with B symptoms (eg, night sweats, fever, weight loss), generalized lymphadenopathy, abdominal distention associated with hepatosplenomegaly, and fatigue. MCL usually affects the lymph nodes, with the spleen and bone marrow being significant sites of the disease. Stage IV disease is present in 70% of patients; the gastrointestinal tract, lung, pleura, and CNS are also frequently affected.
Besides classic MCL, several variants have been described that exhibit specific morphologic features, including small cell variant mimicking SLL marginal zone-like MCL (resembling marginal zone lymphoma), in situ mantle cell neoplasia (associated with indolent course), and two aggressive variants, including blastoid and pleomorphic MCL. These blastoid and pleomorphic variants are defined by cytomorphologic features; the criteria are somewhat subjective, but both are characterized by highly aggressive features and a dismal clinical course. In clinical cohorts, the frequency of these subsets varies widely but probably represents ∼10% of all cases.
Diagnosing MCL requires a multipronged approach. Lymph node biopsy and aspiration with immunophenotyping in MCL reveal monoclonal B cells expressing surface immunoglobulin, immunoglobulin M, or immunoglobulin D that are characteristically CD5+ and pan B-cell antigen positive (eg, CD19, CD20, CD22) but lack expression of CD10 and CD23 and overexpress cyclin D1. Bone marrow aspirate and biopsy are used more for staging than diagnosis. Blood studies commonly reveal anemia and cytopenias secondary to bone marrow infiltration (with 20%-40% of cases showing lymphocytosis > 4000 cells/μL), abnormal liver function tests, and elevated lactate dehydrogenase when tumor burden is high. The term "blastoid mantle cell lymphoma" describes a morphologic subgroup of lymphomas with blastic features that morphologically resemble the lymphoblasts found in lymphoblastic lymphoma/leukemia (roundish nuclei, a narrow rim of cytoplasm, and finely dispersed chromatin).
MCL is associated with a poor prognosis; patients generally experience disease progression after chemotherapy, even with initial treatment response rates ranging from 50% to 70%. The 5-year survival rate is about 50% in the overall population, 75% in persons younger than 50 years, and 36% in those aged 75 years or older. A poorer prognosis is also associated with the presence of the blastoid variant, commonly associated with TP53 mutations. Median survival can vary by as much as 5 years, depending on the expression of cyclin D1 and other proliferation signature genes.
Karl J. D'Silva, MD, Clinical Assistant Professor, Department of Medicine, Tufts University School of Medicine, Boston; Medical Director, Department of Oncology and Hematology, Lahey Hospital and Medical Center, Peabody, Massachusetts.
Karl J. D'Silva, MD, has disclosed no relevant financial relationships.
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