A 58 year old man presents with pain and blackish discoloration of his right little toe for 1 week, in a background of exertional dyspnea, fatiguability and intermittent headaches for 4 months. No other symptoms are present. He has no known medical conditions and has never smoked. At a recent checkup, a fasting blood sugar, lipid profile, liver and renal profile, ECG, chest x-ray and echocardiogram were found to be normal.
WBC: 14,500/mm3 (N:73%) Hb: 18.5 g/dl Hct: 60% Platelet: 846,000/mm3 Blood film: Normocytic-normochromic erythrocytosis, neutrophilia with a left shift and thrombocytosis with normal morphology. No abnormal cells.
The ultrasound scan of the abdomen shows minimal splenomegaly. No other abnormalities are present.
The bone marrow biopsy shows a hypercellular marrow with prominent erythroid, granulocytic and megakaryocytic proliferation. No abnormal cells are seen.
The serum erythropoietin level is 2.3 mU/ml (normal range: 4.3 to 32.9)