Objectives: Systemic Mastocytosis (SM) is a haematopoetic disorder of mast cells. Within bone it has been reported to cause osteoporosis, osteosclerosis or sometimes a mixed pattern. We describe a rare presentation of SM as an exophytic mass causing spinal cord compression.

Methods: 72 year old gentleman was admitted with progressive worsening in mobility and a heavy sensation in his bilateral lower limbs. There was no bowel or bladder symptoms. He subsequently developed severe weakness and was unable to mobilise for 48 hours prior to his admission. On examination he was myelopathic with a sensory level at approximately T10/11. MRI whole spine revealed a heterogeneous lesion involving the vertebral body and posterior elements of T10.

Results: The patient underwent T9-T11 laminecetomy with intra-lesional debulking of metastatic spinal column tumour. Post operatively patient was noted to have improved anti-gravity power in lower limbs. Intra-operative biopsy samples revealed focal paratrabecular infiltrates of abnormal mast cells with collagen fibrosis and focal bone destruction, along with cytogenetic features in keeping with SM.

Conclusions: We describe the rare case of SM presenting as an extradural lesion causing compressive myelopathy and paraparesis. To our knowledge, this has only been described once before in literature. The patient underwent decompression surgery with improvement in neurology post operatively. He was subsequently referred to the haematology team for further investigation and management.