Spinal epidural angiolipoma
Very slowly progressive thoracic myelopathy over years, with T6 sensory level by time of presentation.
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T2-T6 posterior epidural tumor extends from right to left foramina and causes mild expansion of the bony canal. There are anterior displacement and compression of the spinal cord.
The tumor is heterogeneous on T1 and T2, predominately dark on T1, mildly hyperintense on T2. The lower portion of tumor has more focal dark T1 and intermediate T2 areas. Some peripheral flow void seen, difficult to differentiate from normal epidural vessels. The tumor shows avid enhancement.
On more detailed analysis, there is internal fatty tissue, but not a dominant feature on first inspection.
Histology: Abundant ectatic thin-walled vessels with intervening mature adipose tissue in ratio varying between 1:2 to 2:3.
This is a rare benign tumor. The configuration is fairly characteristics - thoracic, posterior epidural, multiple levels, extends from left to right foramina, bony canal widening.
A pre-operative diagnosis, apart from relying on its shape and location, is possible if there is significant amount of fatty content. But if the tumor is highly vascular, the fat may not be as obvious, and tumor looks more like a nonspecific soft tissue tumor. As the vessels are of low flow characteristics, flow void is not commonly seen; but will be a helpful hint if present.
Features against other epidural lesions are:
- Not typical shape for meningioma or schwannoma; although the T2 characteristics, in this case, looks almost like mix zones of Antoni A and B fibers.
- Not enough fatty tissue to be lipoma or low-grade liposarcoma. High-grade liposarcoma is unlikely given the long history and bony remodelling.
- Not typical appearance for vascular malformation or bony lesions with extraosseous soft tissue mass.
- 1. Nan-Han Leu, Cheng-Yu Chen, Cherng-Gueih Shy, Chiao-Yi Lu, Chin-Shun Wu, De-Cheng Chen, Tai-Hong Guo. MR Imaging of an Infiltrating Spinal Epidural Angiolipoma. (2003) American Journal of Neuroradiology. 24 (5): 1008. Pubmed
- 2. J M Provenzale, R E McLendon. Spinal angiolipomas: MR features. (1996) American Journal of Neuroradiology. 17 (4): 713. Pubmed
- 3. M Mascalchi, G Arnetoli, G Dal Pozzo, S Canavero, C A Pagni. Spinal epidural angiolipoma: MR findings. (1991) American Journal of Neuroradiology. 12 (4): 744. Pubmed