Severe pancytopenia associated with moderate hepatosplenomegaly, increased serum lactic dehydrogenase (LDH) levels, and hypogammaglobulinemia were found in a young male patient. Bone marrow histology showed extensive fibrosis, hypoplasia of erythro- and granulocytopoiesis, and hyperplasia of megakaryocytopoiesis associated with histiocytic fat cell phagocytosis and infiltration of abnormal lymphocytes, compatible with lymphoid myelofibrosis. Striking chromosomal aberrations indicating karyotype evolution were also demonstrated by cytogenetic analyses (47, XY, +3 / 47, XY, +3, 1p+ / 46, XO, +3, 1p+, -Y). The clinical course was characterized by cyclic febrile episodes accompanied by excessive increase of serum LDH levels and leukocyte counts, and decrease of platelet counts, followed by spontaneous regression. Further diagnostic procedures, including two liver biopsies and computed tomography, did not detect any manifestation of lymphoma. Eventually, the patient developed rapidly progressive, lethal pulmonary aspergillosis. At autopsy, high grade B cell lymphoma of the liver was found. In this case, the lymphoid myelofibrosis seen on bone marrow biopsy may be considered as a manifestation of "discordant" bone marrow histology related to high grade lymphoma. With respect to the cyclic clinical course, a possible role of apoptotic mechanisms in the physiopathology of this disorder is reviewed.