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  1. One of the most common and usually benign fetal brain tetralogy pathology.

  2. Easily detected due to its obvious anechoic appearance at places that should not be located present.

  3. Larger cysts may exert pressure on adjacent organs causing displacement of structures or obstruct the flow of cerebrospinal fluid.

  4. Although mostly isolated, they can be associated with other pathologies, therefore targeted neuroscan and anatomy scan is warranted.

Intracranial cysts are relatively common findings encountered in the prenatal sonographic assessment of the fetal brain. The vast majority of these fluid collections (arachnoid and choroid plexus cysts) are of a benign nature, remain clinically silent, do not evolve, and regress spontaneously. When these lesions are not associated with other fetal anomalies, they are compatible with normal life regardless of whether they require postnatal treatment or not.1,2 Nevertheless, due to the numerous differential diagnostic entities, as well as the associated parental anxiety, clinically, these findings present a dilemma in need of appropriate diagnosis and counseling.

The differential diagnoses of intracranial cysts encompass multiple etiologic and pathologic processes. Advancements in imaging techniques, especially in fetal sonography, have facilitated the workup of such cysts by depicting their exact location, size, relationship to the ventricular system, and midline structures. Additionally, fetal sonography allows for evaluation of the presence of solid components seen in cases of brain tumors or blood clots and for performance of Doppler studies of blood flow patterns in cases of vascular malformations, such as an aneurysm of the vein of Galen. Nevertheless, imaging studies may come short of distinguishing between some of these lesions, which require histologic examination of the cyst wall to establish the correct diagnosis.3 In this chapter, we classify intracranial cysts based on the location of their origin into one of three groups: extra-axial, intraventricular, and intraparenchymal (Table 11–1).




This group of lesions consists of arachnoid cysts, glioependymal cysts, endodermal cysts, cystic teratomas, and dural separation due to dural sinus thrombosis.

Arachnoid Cysts

Arachnoid cysts are by far the most common lesion in this group, and our review will focus on them.




Arachnoid cysts were first described by Bright in 18313 as "serous cysts forming in connection with the arachnoid and apparently lying between its layers." Like other ...

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