Neoplasms of haematopoietic or lymphoid tissues

**Definition:** A neoplasm arising from hematopoietic or lymphoid cells found in the bone marrow, peripheral blood, lymph nodes and spleen (organs of the hematopoietic or lymphoid system). Hematopoietic or lymphoid cell neoplasms can also involve other anatomic sites (e.g. central nervous system, gastrointestinal tract), either by haematogenous spread, direct tumour infiltration, or neoplastic transformation of extranodal lymphoid tissues. The commonest forms are the various types of leukaemia, Hodgkin and non-Hodgkin lymphomas, myeloproliferative neoplasms and myelodysplastic syndromes.

**Exclusions:** - Malignant neoplasm metastasis in bone or bone marrow - Malignant neoplasm metastasis in lymph nodes - Malignant neoplasm metastasis in spleen - Malignant neoplasm metastasis in thymus gland