Serous atrophy of bone marrow is a non-neoplastic bone marrow disorder that occurs with chronic illness and poor nutritional status. It is characterised by atrophy of the fatty marrow and loss of haematopoietic cells, replaced by an accumulation of extracellular mucinous substances.
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Terminology
Serous atrophy of bone marrow is the preferred term for this disorder, which has also been termed gelatinous marrow transformation 7.
Clinical presentation
Patients can develop osteoporosis and may present with insufficiency fractures.
Pathology
Serous atrophy can be evident in:
anorexia nervosa or other eating disorders
alcohol excess
acute febrile illness
malignancy
Radiographic features
Plain radiograph
severe soft tissue wasting
CT
subcutaneous and visceral fat are nearly absent
MRI
MRI shows striking changes in the fat. Fluid intensity regions in the marrow that are initially patchy but become confluent. These progress in the same order as red to yellow marrow conversion: distal extremities to proximal extremities and axial skeleton. Similar signal abnormalities can usually be observed in the adjacent subcutaneous fat 6.
Signal characteristics
T1: mildly low signal intensity
STIR: high signal intensity
T1 C+ (Gd): non-enhancing bone marrow
Practical points
knowledge of this condition is important so as not to subject the patient to a repeat MRI out of concern that the study is technically faulty
visceral and subcutaneous fat are nearly absent, which should alert the interpreter to the condition
serous marrow does not enhance, differentiating from a diffuse infiltrating malignancy which will enhance after contrast administration 7
serous marrow is often associated with insufficiency fractures, which may be obscured on MRI by the abnormal bone marrow signal
CT can be used as a problem-solving tool to further assess for an insufficiency fracture that cannot be visualised on MRI