Postradiation lumbosacral radiculopathy with spinal root cavernomas mimicking carcinomatous meningitis

Abstract

Lumbosacral radiculopathy is a rare complication of radiotherapy and may be challenging to differentiate from diagnosis of a tumor recurrence. We reviewed the records of three patients with a past history of cancer and radiotherapy who were referred for suspicion of carcinomatous meningitis on lumbar MRI, but whose final diagnosis was radiation-induced lumbosacral radiculopathy. The three patients developed a progressive lumbosacral radiculopathy at 20, 13, and 47 years after lumbar radiotherapy delivered for renal cancer, Hodgkin's disease, and a seminoma, respectively. MRI showed a diffuse, nodular enhancement of the cauda equina nerve roots on T1 sequences, suggestive of leptomeningeal metastasis. A slowly progressive clinical course over several years and negative cerebrospinal fluid cytologic analysis ruled out the diagnosis of carcinomatous meningitis. Because of the radiologic findings, a biopsy was performed in two patients. In the first, a biopsy limited to the arachnoid excluded a malignant infiltration. In the second, a biopsy of the enhancing lesions demonstrated spinal root cavernomas. These observations, together with three recent case reports in the literature, delineate a syndrome of "radiationinduced lumbosacral radiculopathy with multiple spinal root cavernomas" that mimics carcinomatous meningitis on MRI. Its diagnosis is important in order to avoid inappropriate treatment and useless or dangerous spinal root biopsies.

Fig. 1.

Sagittal T2- and T1-weighted MR images of patient 1 demonstrating nodular thickening of cauda equina nerve roots (a, b) with postgadolinium enhancement (c). Increased T2 and T1 signal is present in lumbar vertebral bodies consistent with previous radiotherapy.

Fig. 2.

Postgadolinium sagittal T1-weighted MR images of patient 2 (a) and patient 3 (b) demonstrating nodular enhancement of cauda equina nerve roots.

Fig. 3.

Photomicrograph of the biopsy specimen of the spinal root cavernoma from patient 2 demonstrating large (a) and small (b) blood-filled caverns, lined with a single layer of endothelial cells (hematoxylin and eosin staining, ×40). Adjacent nerve fibers appear to be compressed by the cavernous malformations (arrows).

Fig. 4.

Proposed diagnosis algorithm. CSF, cerebrospinal fluid.