Isolated lymphoid hyperplasia of the bone marrow simulating malignant lymphoma

Lymphoid hyperplasia of the bone marrow occasionally resembles malignant lymphoma and may lead to confusion in bone marrow interpretation. The case of a patient with an unusual variant of isolated bone marrow lymphoid hyperplasia in which histologic overlap with lymphoma was found is presented. The case illustrates the difficulties in bone marrow interpretation that lymphoid hyperplasia can present. One cannot always rely on the number, size, or general pattern of lymphoid nodules to determine whether a lesion is benign or malignant. We suggest that when isolated lymphoid hyperplasia is composed of mature lymphocytes and confined to the marrow, a diagnosis of malignant lymphoproliferative disease should not be made.