Granuloma Annulare Elbow
Heather Borders, MD
over 5 years ago
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Heather Borders, MD
|Diagnostic Category: Developmental or Congenital
|Created: over 6 years ago
|Updated: over 6 years ago
10 year old male with trauma and abnormal outside CT scan.
Patient presented with an outside contrast enhanced CT with a small hyperdense nodule in the upper third ventricle.
MRI demonstrated a small hypointense T1 hyperintense T2/FLAIR cyst in the superior third ventricle without enhancement (the location is slightly posterior to the classically described colloid cyst location). Non contrast CT showed a hyperdense nodule in the upper third ventricle.
Spectroscopy was attempted but was limited due to the small size of the lesion.
Mucin containing cyst at the anterosuperior third ventricle in the area of the foramen of monro (99% are located here). Derived from embryonic endoderm.
Differential: Glioma, SEGA, arachnoid cyst, choroid cyst
Colloid cyst may lead to acute hydrocephalus due to obstruction at the foramen of monro. However, 40-50 % are asymptomatic and incidental.
Cysts are usually 1-2 mm to 30 mm. CT demonstrates hyperdense (2/3) to iso/hypodense (1/3) lesion. No contrast enhancement/possible rim enhancement. MRI demonstrates variable T1 signal (hyperintense in 2/3 to isointense in 1/3). T2/FLAIR is variable and may be misleading. No restricted diffusion or enhancement. MRS-large peak around 2.0 due to colloid.
CT is useful for initial work up and follow up. It may be reasonable to follow small lesions with no evidence of complication. In this patient, a short term follow up scan will be obtained to evaluate for stability.
StatDx: Colloid cyst. Blaise Jones.
American Journal of Neuroradiology 21:1470-1477 Colloid Cyst of the Third Ventricle: Imaging-pathologic Correlation