Diverse arachnoid cyst morphology indicates different pathophysiological origins

Abstract

BackgroundThere are few, limited, and to some extent contradictory, reports on the cellular and subcellular morphology of arachnoid cysts. In the literature cyst membranes are described as similar to, or as vastly different from, normal arachnoid membranes.MethodsThis paper reports electron microscopic analyses of symptomatic cysts from 24 patients (12 males and 12 females; age 10–79), that underwent fenestration surgery. Fourteen cysts were located in the middle cranial fossa (temporal), one in the interpeduncular cistern, five in the posterior fossa, and four were overlying the frontal cortex.ResultsMicroscopic findings confirmed the diverse nature of this clinical condition. Twelve cyst walls resembled normal arachnoid, four had a conspicuous core of dense fibrous tissue with a simple epithelial lining, and the remaining aberrant cysts exhibited non-arachnoid luminal epithelia with plentiful microvilli and/or cilia, and also nervous tissue components in the wall. The possible identity and origin of various cyst types are discussed. We hypothesize that cysts are formed mostly at an early stage of embryonic development, as a teratological event.ConclusionsCysts with various epithelial linings and extracellular components most likely have different barrier properties and fluid turnover characteristics. Further studies are needed to elucidate relations between cyst morphology, fluid composition, pathogenesis, and clinical behaviour including growth rate and relapse tendency.

Intracranial Intra-arachnoid Diverticula and Cyst-like Abnormalities of the Brain

“…18 Evaluation of the lining of these cysts has determined there to be multiple structural variants, which may explain their differential clinical behavior. 22 Secondary intracranial IADs can also occur and represent acquired accumulations of CSF that result from loculation of the subarachnoid space resulting from head injury, intracranial infection/inflammation, neoplasia, or hemorrhage, and are surrounded by arachnoid scarring rather than normal arachnoid tissue. 14,18,23 The mechanism by which a cyst expands is controversial.…”

Can Neonatal Hypoglycemia be Considered a Risk Factor for Development of Acquired Arachnoid Cysts?

“…Rabiei et al established that ACs can have heterogeneous patterns in their wall and fluid microscopical composition, but no defined correlation with their origin and behavior has been found yet. 30 We report this case because we believe that NH had a role in appearance or at least in dimensional increase of our patient's AC. A closer follow-up could be proposed in all infants who have suffered NH, in particular those presenting with seizures, to find out an underlying organic lesion before subjecting them to surgical treatment.…”

Surgical treatment of a large arachnoid cyst with multiple complications

“…Arachnoid cysts are frequently encountered CSF collections in the central nervous system, with preponderance in the middle cranial fossa [3,5]. Recent advances in neuroradiology have translated into increased discovery of these cysts, that is -diagnoses are made more frequently, and at earlier stages.…”