A 31-year old woman with systemic lupus erythematosus since age 8 years, in quiescence for 3 years, was found to be severely anemic, with a hemoglobin of 3.8 g/dL, white blood cell (WBC) count of 2.7 × 10⁹/L, and platelet count of 104 × 10⁹/L. Peripheral smear displayed anisopoikilocytosis, with macro-ovalocytes and abundant teardrop cells without dysplastic WBC changes. Reticulocyte count of 0.3% and erythropoietin level of 973 mIU/mL suggested ineffective erythropoiesis. Serum folate and B12 levels were normal. A bone marrow biopsy showed panmyelosis with >95% cellularity, diffuse reticulin fibrosis, and dysmegakaryopoiesis (panels A [hematoxylin and eosin stain; original magnification ×4] and B-C [hematoxylin and eosin stain (B), reticulin stain (C); original magnification ×20]). Cytogenetic and molecular testing revealed a normal karyotype; JAK2, MPL, CALR, and BCR/ABL mutations were negative. A diagnosis of autoimmune panmyelosis with myelofibrosis was made, and corticosteroids were initiated with complete normalization of hematologic parameters within 4 months of follow-up.

Secondary panmyelosis and myelofibrosis in the setting of an autoimmune illness should be considered to avoid a misdiagnosis of primary myelofibrosis. In the right clinical setting, morphologic features that could suggest this alternate interpretation are lack of dense megakaryocytic clustering and absence of marked megakaryocytic atypia.