28 year old male with pancytopenia (WBC  3.3 K/uL, Hb 7.8 g/dL, Plt 34 K/uL, ANC 1.40 K/uL, ARC 145 K/uL). Peripheral blood shows pancytopenia matching his counts. 

Marrow aspirate showed erythroid hyperplasia with occasional nuclear budding consistent with stressed erythropoiesis. Differential:  1% blasts 18% myeloid, 62% erythroid, 15% lymphocytes, 1%  eosinophils, 2% monocytes, 1% plasma cells

Bone marrow core biopsy is mildly hypercellular with erythroid hyperplasia, decreased megakaryocytes and myeloid precursors, and no increase in CD34 positive cells or blasts.

Identification of large PNH clone by flow cytometry.

Granulocytes (red) in peripheral blood derived from PNH clone are

negative for GPI-linked proteins and FLAER.