A Common Clonal Origin of Nodal Marginal Zone B-Cell Lymphoma and Plasma Cell Myeloma Demonstrating Different Immunophenotypes: A Case Report of Composite LymphomaSaito, Hajime MD*; Oka, Kuniyuki MD†; Nakamura, Naoya MD‡; Nagayama, Reizo MD*; Hakozaki, Hando MD§; Mori, Naoyoshi MD¶Author Information From the *Department of Hematology, Mito Saiseikai General Hospital, Mito, Ibaraki, Japan; †Department of Pathology, Mito Saiseikai General Hospital, Mito, Ibaraki, Japan; ‡Department of Pathology, Fukushima Medical University School of Medicine, Fukushima, Japan; §Department of Pathology, Fukushima Rosai Hospital, Iwaki, Fukushima, Japan; and ¶Department of Pathology of Biological Response, Nagoya University, Graduate School of Medicine, Nagoya, Aichi, Japan. Supported by a grant-in-aid from Mito Saiseikai General Hospital (MSGH), Mito, Ibaraki, and TAKE-TOSHI Medical Research Fund, Oyama, Tochigi, Japan. Reprints: Kuniyuki Oka, MD, Department of Pathology, Mito Saiseika General Hospital, 3-3-10 Futabadai, Mito, Ibaraki 311-4198, Japan (e-mail: email@example.com). Diagnostic Molecular Pathology: June 2004 - Volume 13 - Issue 2 - pp 75-80 Buy Abstract We demonstrated an 83-year-old male case of composite lymphoma. Before 18 years, he was diagnosed with nodal marginal zone B-cell lymphoma in the cervical lymph node. Peripheral blood showed anemia and IgA (κ)-type monoclonal gammopathy (IgA; 3,625 mg/dL). Bone marrow aspiration biopsy exhibited plasma cell myeloma, in which atypical plasma cells were positive for cytoplasmic IgA (κ) and atypical lymphoid cells intermingled were positive for CD20. In contrast, cervical lymph node biopsy revealed nodal marginal zone B-cell lymphoma, in which lymphoma cells were positive for cytoplasmic IgG (λ). Southern blotting analysis of the IgH gene showed same clonal rearrangement band in both lymph node and bone marrow samples and additional band in the bone marrow. Sequence analyses of the IgH gene showed an identical sequence of CDR3 in both samples. Thus, we demonstrated a common clonal origin of composite lymphoma comprising nodal marginal zone B-cell lymphoma and plasma cell myeloma. Nodal marginal zone B-cell lymphoma recurred in cervical lymph node and involved into the bone marrow, differentiating into plasma cell myeloma in which Ig isotype switched and monoclonal gammopathy developed. Sequence analysis of the IgH gene was a powerful tool for determination of clonal origin. © 2004 Lippincott Williams & Wilkins, Inc.