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Neuroradiology Case of the Week

Case 199

Devang Butani, MD and Per-Lennart Westesson, MD, PhD, DDS

Clinical Presentation: Patient is a 49-year-old male patient with psychosis.  Of note, patient is an immigrant from Italy, and a butcher by occupation.

Radiological Findings: Figures 1, 2 and 3, all show punctate calcifications without edema.

Diagnosis: Inactive parenchymal neurocysticercosis

Discussion: Multiple punctate calcifications primarily at the gray-white matter interface, not in any specific vascular distribution. Differential diagnoses specific to this pattern include inactive neurocysticercosis (NC) or other parasitic infection or hemorrhage. Pattern of lesion distribution does not conform to a specific vascular territory, which rules out hemorrhage. Absence of surrounding edema makes active disease less likely, especially given the degree of calcification. No lesions consistent with active infection (as described below) are noted.
     The  4 stages of cysticercosis infection and their associated CT findings are shown below:

1. Vesicular stage (viable larva):  Smooth, thin walled cyst, visualization of a relatively radiolucent protoscolex within the cyst, no wall enhancement or surrounding edema.
2. Colliodal vesicular stage (degenerating larva):  hyperdense fluid, thicker ring enhancing fibrous capsule with surrounding edema.
3. Granular nodular (healing):  Involuting enchancing nodule, with decreasing edema.
4. Nodular calcified (healed):  Shrunken, calcific nodule.

     MR findings for  degenerating larvae (active disease) include hypointense cyst and isointense nodule on T1WI,  hyperintense cyst with edema on T2WI, hyperintense on FLAIR.
     The only truly reliable standard for diagnosing NC is pathologic confirmation through biopsy or autopsy. Nevertheless, even without definitive scientific data, CT scan and MRI are considered the main tools for the diagnosis of NC. MRI is a superior imaging study for intraventricular or subarachnoid cysts, while CT is better for calcification of inactive lesions. Lesions at different stages are not uncommon. Multiple calcifications disseminated in the parenchyma with viable cysts and transitional stage lesions are actually the rule as opposed to the exception in NC.

References:

1. Osborn AG, Blaser SI, Salzman KL. Pocket Radiologist. Brain. Amirsys, W.B. Saunders Co, 2002.  pg 53.
2. Ellison D, Love S (Eds.). Neuropathology. Mosby, 1998.
3. Khosla A. Cysticercosis, CNS. http://www.emedicine.com/radio/topic203.htm
4. www.learningradiology.com - Case of the Week 154- Neuroradiology: Toxoplasmosis