Pathology of autoimmune myelofibrosis - A report of three cases and a review of the literature

We identified 3 patients with autoimmune myelofibrosis (AM) lacking America n Rheumatism Association criteria for systemic lupus erythematosus (SLE). T hey had I or 2 cytopenias and lacked serologic evidence for SLE. Autoimmune features included psoriatic arthritis and positive direct Coombs test (DCT ) result, DCT-positive autoimmune hemolytic anemia, and synovitis with poly clonal hypergammaglobulinemia. Bone marrow biopsy specimens from each patie nt were evaluated by routine morphologic and immunohistochemical examinatio n. They demonstrated marked hypercellularity (2 cases) or hypocellularity ( I case), moderate erythroid hyperplasia (all cases) with left-shifted matur ation (2 cases), intrasinusoidal hematopoiesis (all cases), slightly to mod erately increased megakaryocytes (2 cases), and grade 3 to 4 reticulin fibr osis (all cases). All lacked basophilia, eosinophilia, bizarre megakaryocyt es, clusters of megakaryocytes, and osteosclerosis. Mild to moderate bone m arrow lymphocytosis was noted in all cases. In 2 cases, increased small T c ells and B cells formed nonparatrabecular, loose aggregates. AM is a clinic opathologic entity that may lack features of SLE. Loose aggregates of bone marrow T and B lymphocytes and the absence of morphologic and clinical feat ures of myeloproliferative disease or low-grade lymphoproliferative disease are clues that distinguish AM from better known causes of bone marrow fibr osis.