Haematopoetic bone marrow reconversion

Case contributed by Domenico Nicoletti


Knee pain in a patient with thalassemia major, previous acute lymphoblastic leukemia in complete remission and post-transfusion hemosiderosis under treatment.

Patient Data

Age: 35 years
Gender: Male

MRI left knee


Reconversion along with a diffuse lowering of red marrow signal intensity on T1-weighted images and greater lowering of signal intensity on T2-weighted images (susceptibility changes) resulting from hemosiderin in the marrow cavity.

Hematological examination report


Italian to English translation: Patient suffering from thalassemia major transfusion-dependent with hypercalciuria, renal tubule alteration, post-transfusional hemosiderosis, metabolic osteopenia with secondary hypercalciuria, biliary sludge. 1997 splenectomy, 2001 diagnosis of acute lymphoblastic leukemia undergoing chemotherapy with complete remission. 2014 Quantiferon positive, subsequent six-month therapy with isoniazid.

Case Discussion

The fatty marrow that is typically present in the distal femur and proximal tibia of a patient this age has been largely reconverted to hematopoietic marrow. The large fraction of red marrow present in the distal femur and proximal tibia is evidenced by decreased overall marrow signal intensity at these sites. Note that there has even been some reconversion of yellow marrow to red marrow in the epiphyses.

Generally, reconversion will become evident in the distal metaphyses of long bones before it has been completed in the diaphyses. Some patients without known bone marrow disorders can display evidence of expanded red marrow fractions in the axial and appendicular skeleton. This has been called hematopoietic hyperplasia (marathon runners, heavy smokers, obese women who smoke, and patients under the age of 40 years).

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