Hematopoietic bone marrow within the proximal humeral epiphysis in normal adults: investigation with MR imaging

The occurrence of hematopoietic bone marrow within the axial skeleton and meta-diaphyseal regions of long bones is well known. However, it has been generally accepted that hematopoietic marrow is not present within the epiphysis of long bones in normal adults. This study involved evaluation of marrow patterns in 96 patients presenting for shoulder magnetic resonance (MR) imaging examinations. Residual hematopoietic marrow was present within the proximal humeral metaphysis in 99% of patients and extended into the epiphysis in 62%. Epiphyseal hematopoietic marrow was more prominent in female subjects (P = .015) and showed correlation with prominence of hematopoietic marrow within the proximal humeral metaphysis (P = .01). The most characteristic pattern was a curvilinear distribution of hematopoietic marrow involving the subcortical region of the medial humeral head, though in some patients more centrally located patchy or globular regions of hematopoietic marrow were observed. These findings indicate that when signal intensity variations are observed within the epiphysis on MR images, the possibility of residual or reconverted hematopoietic marrow should be considered.