CNS Lipoma

A 62-year-old African American woman was brought to the emergency department (ED) after the sudden onset of slurred speech and weakness in her left arm and leg. Her medical history included hypertension, insulin-dependent diabetes, and congestive heart failure.

Imaging studies showed a small lesion in the left portion of the thalamus, consistent with a lacunar stroke, and generalized brain atrophy. No acute stroke interventions were initiated, since the patient came to the ED more than 3 hours after the onset of symptoms.

Also noted on the CT of the brain was a large hypodense midline mass that measured 4 × 7 cm with minimal mass effect (A). An MRI depicted the same structure, which appeared to be atrophic and extended from the genu to the splenium region of the corpus callosum.

The axial T₁-weighted and sagittal T₂-weighted images (B, C) showed the intensity of the mass as consistent with that of fat. A diagnosis of CNS lipoma was made.

Dr Roman Kesler of the University of South Alabama College of Medicine in Mobile writes that a CNS lipoma is composed of mature adipose tissue. This mass tends to occur in the midline of the brain, especially in the corpus callosum area, and the spinal cord.

As in this case, lipomas usually are found incidentally. Rarely, patients with a lipoma will have focal neurologic complaints, particularly when the mass arises in the spinal cord where it may compress nerve roots and produce radicular symptoms. Surgical excision may become necessary.

Most often, CNS lipomas are associated with dysraphisms and other congenital anomalies, such as agenesis of the corpus callosum. Generally, no treatment is needed because these lesions are benign.

This patient was treated for the ischemic stroke that caused her slurred speech and left-sided weakness. Her condition slowly improved over several weeks.