Serous atrophy of bone marrow

Serous atrophy of bone marrow is is a non-neoplastic bone marrow disorder that occurs with chronic illness and poor nutritional status. It It is characterised by atrophy of the fatty marrow and loss of haematopoietic cells, replaced by an accumulation of extracellular mucinous substances.

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:

• cachexia

• anorexia nervosa or or other eating disorders

• AIDS

• alcohol excess

• acute febrile illness

• malignanciesmalignancy

• chronic renal failure

• congestive heart failure

• myelodysplastic syndrome

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.

• T1: mildly low signal intensity

• STIR: high signal intensity

• T1 C+ (Gd): non 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