Nelson Marvin D, Maher Karima, Gilles Floyd H
Department of Radiology, Keck School of Medicine, Children's Hospital, Los Angeles, University of Southern California, 4650 Sunset Blvd, MS #81, Los Angeles, CA 90027, USA.
Pediatr Radiol. 2004 Sep;34(9):720-32. doi: 10.1007/s00247-004-1253-1. Epub 2004 Jul 30.
Posterior fossa cysts are frequently identified on MR studies. This paper takes a different approach to analyzing these cysts based on the pathology of the cyst wall and the embryology of the hindbrain, choroid plexus, and meninges. The type of cyst depends on the histologic components of the cyst wall. Frequent types of posterior fossa cysts are arachnoid, Blake's pouch, and cysts associated with Dandy Walker malformation. All of these cysts may mimic the others in terms of position of the torcula, vermian abnormalities, and mass effect on the cerebellum and occipital bone. A clue to the nature of the cyst may be the position of the choroid plexus in the fourth ventricle; normal in arachnoid cyst, absent in Dandy Walker malformation, and displaced into the superior cyst wall in Blake's pouch. When the cyst wall histology is not known, it is suggested to use a descriptive term such as "retrocerebellar cyst".
后颅窝囊肿在磁共振成像（MR）研究中经常被发现。本文基于囊肿壁的病理学以及后脑、脉络丛和脑膜的胚胎学，采用不同方法对这些囊肿进行分析。囊肿的类型取决于囊肿壁的组织学成分。后颅窝囊肿常见类型为蛛网膜囊肿、Blake囊肿以及与Dandy-Walker畸形相关的囊肿。所有这些囊肿在窦汇位置、蚓部异常以及对小脑和枕骨的占位效应方面可能相互类似。囊肿性质的一个线索可能是第四脑室内脉络丛的位置；蛛网膜囊肿中正常，Dandy-Walker畸形中缺如，而在Blake囊肿中则移位至囊肿上壁。当囊肿壁组织学情况不明时，建议使用描述性术语，如“小脑后囊肿”。
