Importance of axial postcontrast images in the differential diagnosis between inflammatory and neoplastic spinal cord enlargement

Seropositive Neuromyelitis Optica imitating an Intramedullary Cervical Spinal Cord Tumor: Case Report and Brief Review of the Literature

A 44-year-old woman with progressive cervical myelopathy and central cord syndrome was noted to have an extensive cervical intramedullary contrast-enhancing lesion on magnetic resonance imaging (MRI). The lesion resembled a spinal astrocytoma or ependymoma that required surgical intervention. She was subsequently diagnosed to have neuromyelitis optica (NMO), a rare idiopathic inflammatory demyelinating disorder, when the clinical examination revealed left optic atrophy. This was confirmed by a test showing seropositivity for NMO-immunoglobulin (IgG). Disease control was achieved with corticosteroids and immunosuppressive therapy. We report a rare case of a patient with NMO who had MRI features that could have easily led to the condition being misdiagnosed as a spinal cord tumor. The importance of careful history taking, awareness of typical radiological findings and the usefulness of serum NMO-IgG as a diagnostic tool are emphasized.

Spinal cord tumor versus transverse myelitis

BACKGROUND CONTEXT

Longitudinally extensive transverse myelitis (LETM) is one of the defining features of neuromyelitis optica (NMO). Despite the well-established criteria, clinical and paraclinical features, the disease is often misdiagnosed and erroneously treated.

PURPOSE

We report on a case of LETM in a patient with spatially limited NMO spectrum disorder that was misdiagnosed as spinal cord tumor and underwent spinal cord biopsy.

STUDY DESIGN

A 43-year-old female patient is described.

METHODS

The patient developed spastic tetraparesis over 1 week. Spinal cord magnetic resonance imaging (MRI) revealed LETM, and she was treated with steroids and recovered. Nine months later, her condition worsened and repeat spinal cord MRI was interpreted as a large intramedullary tumor in the cervical region with irregular postcontrast enhancement. Biopsy revealed demyelination. Cerebrospinal fluid (CSF) analysis revealed positive oligoclonal IgG bands, and serum was positive for NMO-IgG antibody.

RESULTS

The patient was diagnosed with spatially limited NMO spectrum disorder, treated with plasma exchange, high-dose corticosteroids, and cyclophosphamide, and with good recovery.

CONCLUSIONS

The factors favoring inflammatory LETM are acute or subacute onset of clinical symptoms, positive oligoclonal bands in the CSF, positive NMO-IgG or other antibodies, and brain MRI showing demyelinating lesions. Postcontrast axial MRI sequences of the spinal cord can also be helpful. In doubtful situations, a trial of therapy and follow-up MRI a month later might be a more prudent approach if the patient is not rapidly deteriorating.