Case of the Week
Section Editors: Matylda Machnowska1 and Anvita Pauranik2
1University of Toronto, Toronto, Ontario, Canada
2BC Children's Hospital, University of British Columbia, Vancouver, British Columbia, Canada
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October 13, 2022
Serous Fat Atrophy
- Background:
- Serous fat atrophy, also known as “gelatinous marrow transformation” or “starvation marrow,” is a nonspecific finding associated with severe illness and poor nutritional status (folic acid/B12 deficiency).
- Pathophysiology: In starvation states, there is a mobilization of marrow fat, which is subsequently replaced by a gelatinous substance.
- Most commonly seen in young and middle-aged adults with a 2:1 male predominance
- Associated with anorexia nervosa, cancer-related cachexia, end-stage renal disease, myxedema, cytotoxic drugs, infection (eg, HIV/AIDS, tuberculosis), and alcoholism
- Histologically described by 1) fat cell atrophy, 2) loss of hematopoietic cells, and 3) deposition of gelatinous extracellular substance
- Bone marrow core biopsy with microscopic examination necessary to make final diagnosis
- Clinical Presentation:
- Clinical presentation usually involves severe weight loss and anemia along with deficiencies in vitamins and trace elements.
- Insufficiency fractures related to osteoporosis may be seen.
- Key Diagnostic Features:
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MRI shows marrow signal that is hypointense to muscle on T1WI and hyperintense to muscle on T2WI.
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Waterlike SI pattern due to gelatinous transformation
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STIR and fat-suppressed fluid-sensitive images display high signal intensity.
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Fractures can be difficult to distinguish due to marrow signal abnormalities.
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MRI findings can be misinterpreted as technical error, leading to unnecessary repeat imaging.
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Signal enhancement in the vertebral body is abnormal for isolated serous fat atrophy (as seen in this case), but it has been reported elsewhere (see reference 5).
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- Differential Diagnoses:
- Atypical hemangioma (fat-poor)
- Characteristic coarsened trabeculae seen on CT
- T1WI shows low signal due to lipid-poor content.
- T2 FSE images show hyperintense signal.
- Plasmacytoma
- “Punched-out” lytic lesions with no identifiable matrix
- “Soap bubble” of advanced lesions with expansion and destruction of cortex and thick ridging around the periphery
- No systemic bone marrow involvement
- Lymphoma (primary and secondary)
- Hyperdense on CT
- Hypointense on T1WI
- Multiple myeloma
- Lytic bone lesions
- Endosteal scalloping
- Metastatic deposit
- More likely to affect vertebral pedicles
- Malignancy shows enhancement with gadolinium.
- Atypical hemangioma (fat-poor)
- Treatment:
- Treat the underlying cause; this often entails nutritional support.
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