G‐CSF stimulated islands of haematopoiesis mimicking disseminated malignancy on PET‐CT and MRI scans in a patient with hypoplastic marrow disorder

Abstract

A 25-year-old man was admitted for abdominal pain and bicytopenia (anaemia + thrombocytopenia) in November 2003. Trephine biopsy revealed an aplastic marrow with cellularity less than 5% (panel 5). A diagnostic plan included positron emission tomography-computed tomography (PET-CT) to exclude malignancy before starting immunosuppression. In the week preceding the PET-CT, the patient developed neutropenic sepsis with severe gastro-intestinal bleeding. He was treated with antibiotics and granulocyte colony-stimulating factor (G-CSF). Both PET-CT (panels 3 and 4) and magnetic resonance imaging (MRI) scans (panels 1 and 2) later showed multiple focal lesions highly suspicious of a neoplasm disseminated to the bone marrow. PET-CT-directed surgical biopsy from the S1 vertebral body was performed. No malignant cells were found. Blood clots with small fragments of hypercellular marrow showing trilinear haematopoiesis were obtained (panel 6), probably a consequence of G-CSF administration. Hypercellular islands mimicked malignancy on the scans. The patient later met the criteria of severe aplastic anaemia and in the absence of a human leucocyte antigen-matched related donor underwent immunosuppressive treatment. Paroxysmal nocturnal haemoglobinuria clones appeared in the granulocyte and thrombocyte lines in the course of the disease. The patient has a reasonable quality of life and only occasionally needs a platelet transfusion; his leucocyte numbers are above 2 × 109/l. This case highlights the importance of avoiding the administration of G-CSF prior to PET imaging and illustrates the irregular pattern of distribution of haematopoetic bone marrow in the initial phases of aplastic anaemia.