Ans. B: Myelofibrosis Most patients of myelofibrosis present over the age of 50 years. The spleen can be massively enlarged due to extramedullary haematopoiesis The marrow is often difficult to aspirate Myelophthisic syndrome Primary myelofibrosis: - Due to invading by tumour cells, usually of an epithelial cancer of the breast, lung, and prostate or neuroblastoma - Infections such as TB, HIV, sarcoidosis, Gauchers dsease Secondary myelofibrosis: - Radiation therapy - Treatment with radiomimetic drugs Pathophysiology: - Proliferation of fibroblasts in the bone marrow - Extension of heamatopoiesis into the long bones and most parricularly into extramedullary tissues, usually the spleen, liver, and lymph nodes (myeloid metaplasia) - Ineffectiv eerythropoiesis Blood picture: - Anemia (secondary myelofibrosis) is usually normocytic and normochromic - Erythrocyte morphology is very abnormal, with circulating nucleated RBCs. Tear drop cells etc - Increased WBC count, sometimes mimicking leukaemoid reaction - Bone marrow aspirate: Inability to aspirate bone marrow, the characteristic "dry tap" can allow a presumptive diagnosis