Myelofibrosis is characterized by reticulin fibrosis of the bone marrow with resulting features of myelophthisis. Besides hematopoietic malignancies and other neoplasms involving the bone marrow, myelofibrosis has been described in association with autoimmune disorders, especially systemic lupus erythematosus. We describe the clinicopathologic features of a primary form of autoimmune myelofibrosis (AIMF) in patients who do not have systemic lupus erythematosus or another well-defined autoimmune syndrome. Absence of marked splenomegaly, peripheral blood cytopenias with mild teardrop poikilocytosis and leukoerythroblastosis, bone marrow lymphoid aggregates, and presence of autoantibodies are some of the salient features of primary AIMF. AIMF should especially be differentiated from chronic idiopathic myelofibrosis, a neoplastic myeloproliferative disease. Primary AIMF appears to have an excellent prognosis, with all patients reported in this series responding to a short course of corticosteroid therapy.

We identified 3 patients with autoimmune myelofibrosis (AM) lacking American Rheumatism Association criteria for systemic lupus erythematosus (SLE). They had 1 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 polyclonal hypergammaglobulinemia. Bone marrow biopsy specimens from each patient were evaluated by routine morphologic and immunohistochemical examination. They demonstrated marked hypercellularity (2 cases) or hypocellularity (1 case), moderate erythroid hyperplasia (all cases) with left-shifted maturation (2 cases), intrasinusoidal hematopoiesis (all cases), slightly to moderately increased megakaryocytes (2 cases), and grade 3 to 4 reticulin fibrosis (all cases). All lacked basophilia, eosinophilia, bizarre megakaryocytes, clusters of megakaryocytes, and osteosclerosis. Mild to moderate bone marrow lymphocytosis was noted in all cases. In 2 cases, increased small T cells and B cells formed nonparatrabecular, loose aggregates. AM is a clinicopathologic entity that may lack features of SLE. Loose aggregates of bone marrow T and B lymphocytes and the absence of morphologic and clinical features of myeloproliferative disease or low-grade lymphoproliferative disease are clues that distinguish AM from better known causes of bone marrow fibrosis.

We describe 35 peripheral lymph nodes classified as mantle cell/marginal zone B-cell hyperplasia with clear cells using morphologic and immunologic findings. For the purpose of this study, we obtained clinical follow-up information and performed immunoglobulin gene rearrangement studies on paraffin sections by polymerase chain reaction. Architecturally, the nodes were suggestive of a benign process: no pericapsular infiltration, sinuses readily identified, scattered reactive follicles present, and paracortical nodular hyperplasia present. No monocytoid B cells were present. Focally, small lymphoid cells with round nuclei and clear cytoplasm (clear cells) formed monomorphic nodular, inverse follicular, and/or marginal zone patterns. Flow cytometry and immunohistochemical analysis revealed neither light chain restriction nor an aberrant B-cell phenotype. Immunoglobulin gene rearrangement studies showed a clonal band in 1 of 26 cases in which DNA was amplified. To ascertain the clinical relevance of this positive case, follow-up information was obtained 30 months after the initial biopsy; the 83-year-old woman was alive without treatment but had splenomegaly and bone marrow involvement by marginal zone B-cell lymphoma. The morphologic and immunologic criteria used for diagnosis of mantle cell/marginal zone B-cell hyperplasia with clear cytoplasm are valid; however, to rule out the possibility of occult lymphoma, immunoglobulin gene rearrangement studies and clinical follow-up are necessary.

We report on a case of invasive lobular carcinoma of the breast with a previously undescribed cytologic feature. Diff-Quik-stained cytologic preparations showed uniform single cells with prominent coarse cytoplasmic granules. Ultrastructurally, the granules showed features suggestive of autophagosomes and/or degenerative mitochondria. The cytologic differential diagnosis included granulocytic sarcoma, metastatic melanoma, extramedullary hematopoiesis, large granulocytic leukemia/lymphoma, and mast-cell tumor. Adjunctive studies were helpful in the diagnosis of carcinoma. Histologic study of the mastectomy specimen showed classic type of invasive lobular carcinoma.