Presentation
Referred for assessment of bile ducts at abdominal MR/MRCP by the gastroenterologist. CECT was recommended by the radiologist as an additional exam.
Patient Data
Incidentally discovered expansile fat-containing lesion in the left 12th rib abutting the costovertebral joint and displacing the diaphragm. No appreciable diffusion restriction is noted.
The patient refused to contrast injection at MR and was referred for contrast-enhanced CT.
Expansile, macroscopic fat-containing lesion in the head-neck of left 12th rib, with lobulated borders and cortical thinning. No marked contrast enhancement noted on contrast-enhanced series.
Case Discussion
The MR and CT studies show a lobulated fatty lesion in head-neck of the left 12th rib. The macroscopic contents of fat with sparse soft tissue intensity/density are similar in appearance to that of soft-tissue angiolipomas.
The differential diagnosis could include:
- metastasis of lipid-containing neoplasm: may give the appearance of a benign/non-aggressive lesion
- angiolipoma: subcutaneous, adolescent to young adult. Few case reports of intraosseous angiolipoma 1-4
- liposarcoma: in soft tissues (e.g. retroperitoneum)
- hemangioma: bony trabeculae
- solid variant of aneurysmal bone cyst (giant cell reparative granuloma): solid-cystic, in appendicular long bones
- site of extramedullary hematopoiesis: extraosseous paraspinal, in the presence of a myeloproliferative disorder or hemoglobinopathy
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