venerdì 2 febbraio 2007
There is a well-circumscribed suprasellar mass that is predominantly cystic with focal rim calcifications (Figure 1).
The pituitary gland appears normal (Figure 2). Fluid-fluid level is noted with bright signal on T1-WI (Figure 3), T2-WI and FLAIR (Figure 4 and Figure 5). Post contrast image show minimal enhancement along the periphery of the lesion with no enhancement of the lesion itself.
Craniopharyngiomas are benign dysodontogenic epithelial tumors derived from Rathke pouch epithelium. These tumors are mostly suprasellar (75%), with intrasellar extension seen in 20% of cases.
Two types of Craniopharyngioma are classically described:
1) Childhood form- Peak 5-15 years. Has cyst formation and calcification. Has an adamantinomatous microscopic pattern and carries poor prognosis.
2) Adult form- Peaks in sixth decade. Shows papillary squamous epithelium. Symptoms are usually due to mass effect-headache, visual disturbances, behavioral changes, hydrocephalus, and endocrine dysfunction.
Craniopharyngiomas are WHO Grade I lesions. These are multilobulated, multicystic masses. The cyst may contain variations of highly proteinaceous fluid, cholesterol, and blood products.
On CT, these appear as large, lobulated heterogeneous suprasellar masses. Intrasellar extension may enlarge the sella and cause erosion of dorsum sellae. Cysts may vary in density, depending on contents. Calcification may be peripheral or irregular and nodular.
High-signal intensity within a suprasellar mass should raise suspicion of craniopharyngioma. Cyst contents are typically hyperintense on T2 and FLAIR images. Enhancement is heterogeneous in the solid portion of the tumor, with the cyst walls enhancing strongly. Cyst contents show a broad lipid spectrum on MRS (0.9 ppm to 1.5 ppm). Infiltration is common, making complete surgical resection difficult.