Quadrigeminal Cistern Mass

Gregory L. Katzman, MD, MBA

DIFFERENTIAL DIAGNOSIS

Common

Less Common

Rare but Important

ESSENTIAL INFORMATION

Key Differential Diagnosis Issues

Quadrigeminal cistern (QC) lesions are smaller subset of “pineal region masses”
- Bounded by quadrigeminal plate, splenium, vermis, & tentorial margin
- Extends between layers of tela choroidea
- Contents: Caudal internal cerebral veins, vein of Galen, PCA (quadrigeminal or P3 segment), posteromedial choroidal arteries, CNIV exit
Masses arising from QC itself (and its contents) < < those from nearby structures

Helpful Clues for Common Diagnoses

Helpful Clues for Less Common Diagnoses

Cavum Velum Interpositum (CVI)
- Axial MR/CT shows triangular-shaped CSF space between bodies of lateral ventricles
- FLAIR suppresses completely
Arachnoid Cyst
- Sharply demarcated extra-axial cyst that follows CSF attenuation/signal
- No diffusion restriction
Neurocysticercosis
- Cystic lesion isointense to CSF, may see discrete, eccentric scolex
- Basal cistern cysts may be racemose
Ascending Transtentorial Herniation
- Large posterior fossa mass → upward herniation of vermis → mass effect on quadrigeminal cistern ± obstructive hydrocephalus

Helpful Clues for Rare Diagnoses

Lipoma
- Well-delineated, lobulated, extra-axial mass with fat attenuation/intensity
- Ca++ varies from none to extensive
Epidermoid Cyst
- Lobulated, irregular, CSF-like mass
- FLAIR usually doesn’t completely null; diffusion yields high signal restriction
Vein of Galen Malformation
- Dilated arteries feeding into large midline venous pouch
- Look for prominent “flow voids” and phase artifact