A Rare Case of Spinal Mastocytosis Presenting as an Extradural Mass

Systemic mastocytosis is a hematopoietic disorder of mast cell deposits in various systemic tissues that can include skin, spleen, liver, and bone marrow. When accumulation occurs within bone it has been reported to cause osteoporosis, osteosclerosis, or sometimes a mixed pattern. In exceptionally rare circumstances, it has been reported to present as an exophytic mass causing neural compression.

A 72-year-old man was admitted with progressive worsening in his mobility and heavy and numb sensation in his bilateral lower limbs that worsened on walking. His weakness subsequently progressed such that he was no longer able to mobilize for 48 hours prior to admission. On examination he was found to be myelopathic with a sensory level noted at approximately the T10/11 area. Whole spine magnetic resonance imaging was conducted, which revealed a heterogeneous lesion involving the vertebral body and posterior elements of T10. The patient underwent T9-T11 laminecetomy with intralesional debulking of metastatic spinal column tumor. Postoperatively, the patient was noted to have improved anti-gravity power in the lower limbs. Intraoperative biopsy samples revealed focal paratrabecular infiltrates of abnormal mast cells with collagen fibrosis and focal bone destruction, along with cytogenetic features in keeping with systemic mastocytosis.

We describe a rare case of systemic mastocytosis 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 postoperatively. He was subsequently referred to the hematology team for further investigation and management.