Giant paravertebral myxoma

Abstract

The study design includes case report and clinical discussion. The objective was to describe a rare case of a giant intramuscular myxoma (IMM) presenting as a mass in the paravertebral muscles. Myxoma is a rare benign soft tissue tumour of mesenchymal origin. Although intramuscular presentation is common, they are rare in the paravertebral muscles and are characteristically <5 cm in length. We report the clinical and imaging features in a 70-year-old woman presenting with back pain, asymmetry of the waist and a mass in right paravertebral region. This was originally misdiagnosed as a juxtafacet synovial cyst after CT-guided biopsy. The mass was excised en bloc and sent for histology. This revealed a low-grade myxoid neoplasm with features of an IMM. The patient went on to make a complete recovery. To our knowledge, this is only the fifth case of paravertebral IMM reported in the literature and at approximately 15 cm in length may be the largest encountered in clinical practice.

Fig. 1

Pre-operative US. A well-defined 6-cm area of hypoechogenicity is seen in the right paravertebral musculature

Fig. 2

Pre-operative MRI. T2-weighted sagittal and parasagittal images show a loculated partially cystic mass lying within the right posterior paravertebral musculature. It is causing marked local expansion of the paravertebral musculature, has significant soft tissue component and some worrying bone erosion of the L4 transverse process indicating it may be aggressive in nature

Fig. 3

Pre-operative CT. An extensive soft tissue mass is seen arising from the right posterior elements at the L5 level. The cystic component extends down the posterior aspect of the sacrum. There is bone loss over the left side of the posterior elements of L4 involving the transverse process with expansion of the muscle bellies. The bony effects are seen involving both the posterior aspects of L4 and L5 making this unlikely to be a primary bony lesion, and more likely to be soft tissue in origin. The secondary bony change is in places marked making this lesion likely to have been present for some time

Fig. 4

Intra-operative images. The mass was identified through a midline longitudinal incision and unilateral subperiosteal muscle strip. The mass was dissected free of the surrounding tissue and excised en bloc