Intradural calcifying fibroblastic proliferation associated with a nerve root: a reactive process mimicking a nerve...

Case Report.

To share our experience about the unique histological appearances of a calcified intradural, extramedullary lesion involving a nerve root.

A 53-year-old man presented with a long history of low back pain and a few months of occasional left groin pain with no neurological deficit. Imaging of the spine revealed a calcified intradural extramedullary lesion at L1, separate from vertebrae. Intraoperatively, the lesion was found to involve closely one of the roots and was heavily calcified but relatively easy to excise. The histology revealed calcifying fibroblastic proliferation associated with a nerve root. This is an unusual pathological entity, which appears distinct from the rare but occasionally reported reactive process known, as heterotopic bone formation in a nerve or "neuritis ossificans," and it is important to distinguish it from other calcified intradural neoplasms.

The histology of an excised calcified intradural extramedullary lesion was initially reviewed by our local neuropathologist. A second opinion was requested from Prof. Malcolm, who is a histopathologist and bone specialist. The unique histological features of the lesion were confirmed. The literature (no date limitations) was reviewed.

A calcified intradural extramedullary lesion, closely related to nerve root was found to have unique histological features, not reported in the literature so far.

The histological features of the calcified lesion that we report here have not been described before. It is highly likely they represent a reactive process. We think these features are useful to be added to the differential diagnosis of a calcified intradural extramedullary lesion involving a nerve root.