Report of an unusual small lymphocytic B-cell lymphoma selectively involving the B-zone of lymph node

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Abstract
Selective involvement of the B‐cell compartment of lymph node by B‐cell malignant lymphomas is an occasional finding related to early phases of lymph node infiltration. The authors have observed a unique case of diffuse small lymphocytic lymphoma that consisted of immunohistologically and genotypically proven B‐clonal population exhibiting a repetitive pattern of infiltration in three lymph node samples obtained from the patient during a 9‐year period. This pattern consisted of a selective and complete replacement of the B‐areas with disappearance of follicles and widening of the medullary cords, an expanded T‐zone showing features consistent with dermatopathic lymphadenitis and well‐preserved sinuses. Clinically, multiple involved sites at presentation (lymph nodes, spleen, skin, bone marrow, and peripheral blood) and during the 9‐year follow‐up (testis) were detected, and the disease was associated with a relative indolent course like other low‐grade lymphomas. The phenotypic profile of lymphoma cells studied by immunoperoxidase method, and by single‐labeling and double‐labeling flow cytometric analyses (SIg+, K+, LN2+, MB1+, MB2+, HLA‐DR+, CD 9+, CD19+, CD20+, CD 21+, CD 22+, CD 24+, Leu 8+, CD 5–, CD 10–, CD 11b–, CD 11c–, CD 25–, CD 38–, PCA‐1–, FMC‐7–, CD 23–) was consistent with a B‐cell proliferation at an intermediate stage of differentiation but distinct from other well‐defined B‐cell neoplasms. Whether such unique B‐zone pattern was due to an intrinsic property of this lymphoma or it is to be related to the coexisting reactive T‐zone expansion remains controversial.