Endometrial extramedullary haemopoiesis.

Four cases of endometrial extramedullary haemopoiesis are reported, all with associated haematological disease. The diagnoses of a myeloproliferative disorder and thalassaemia trait were made as a consequence of the histological observations and subsequent haematological investigations in two cases. The third case occurred in a patient with an established diagnosis of chronic myeloid leukaemia. The diagnosis of extramedullary haemopoiesis in the final case was made on autopsy material from a patient with multiple myeloma. The endometrium from five other women with known myelofibrosis was examined but extramedullary haemopoiesis was not found. Endometrium from 32 fetuses did not contain haemopoietic elements, excluding the likelihood of the endometrium being a common site for extramedullary haemopoiesis in development. Endometrial extramedullary haemopoiesis is an uncommon finding, but it is worthy of note, as it may herald the presence of an underlying haematological abnormality.