The Variable Appearance of Third Ventricular Colloid Cysts: Correlation with Histopathology and the Risk of Obstructive Ventriculomegaly

Rate of Missed Intracranial Colloid Cysts on MRI and CT

BACKGROUND AND PURPOSE

Intracranial colloid cysts of the third ventricle are rare; however, they may be symptomatic. They can create a mass effect on the foramina of Monro, resulting in acute hydrocephalus. Colloid cysts are detectable on CT and MRI but are commonly missed. In this paper, we investigate the rate of missed colloid cysts on MRI and/or CT imaging within our multihospital metropolitan medical group.

MATERIALS AND METHODS

A retrospective, institutional review board-approved search of the network-wide picture archiving and communication system (PACS) from January 1, 2010, to October 31, 2020, was performed to identify reports including a "colloid cyst" in MRI brain or CT head imaging. Results without imaging and/or surgical confirmation of intracranial colloid cysts were excluded, rendering 229 cases. A PACS review of these cases was performed by two neuroradiologists to determine instances where the cyst had previously been imaged but not diagnosed on either CT or MRI.

RESULTS

Two hundred twenty-nine subjects had confirmed colloid cysts through imaging and/or surgical reports. Of these, 46 had prior imaging depicting a colloid cyst either on CT and/or MRI without mention on the interpretative report, resulting in a non-detection rate of 20.1%.

CONCLUSION

Intracranial colloid cysts can be missed at a considerably high rate, which is concerning given their clinically unpredictable nature and ability to cause significant morbidity and mortality. As such, it is important to take a proactive approach to searching for these cysts as part of a regular imaging search pattern and to continue to determine new methods of increasing detection sensitivity.

Acute hydrocephalus caused by colloid cyst of third ventricle: A case report

Colloid cysts (CCs) of third ventricle are rare benign lesions. They present with acute hydrocephalus and its sequalae like brain herniation, infarcts resulting even death in otherwise healthy individual. We present a case of an acute hydrocephalus caused by CC of third ventricle. A middle age male was airlifted from a remote district of Nepal to our hospital with no accompanying doctor. The patient had headache, multiple episodes of vomiting, abnormal body movement, and loss of consciousness for 24 hours. On examination, vitals were stable; the Glasgow Coma Scale (GCS) score was 7. The patient was intubated in emergency and an MRI brain was done. MRI showed an obstructive lesion in third ventricle with features consistent with CC and an active hydrocephalus. There were multifocal infarcts in the bilateral cerebrum, left part of mid brain and pons, left thalamus and left superior cerebellum. We inserted external ventricular drainage in emergency operation theatre within hours and endoscopic excision of the lesion was done on the next day. In histopathology, the lesion was confirmed to be a CC.

Intraventricular sizeable colloid cyst with atypical radiological features: A case report and evidence-based review

Colloid cysts are benign intracranial lesions, typically located in the anterior portion of the third ventricle near the interventricular foramina of Monro. The cysts usually consist of an epithelial lining filled with viscous gelatinous material of various components. Colloid cysts are generally asymptomatic, but once symptomatic, they can present in a variety of ways, including headaches, vomiting, visual and memory problems, and vertigo. Colloid cysts present classically on imaging as a well-delineated hyperattenuating lesion on unenhanced radiological modalities. Herein, we report a case of a patient who presented with hydrocephalus caused by a sizeable colloid cyst which demonstrated atypical imaging findings in the form of hypodensity on CT and hyperintensity on T2WI, making them difficult to identify and easy to miss. Although this atypical imaging appearance is uncommon with yet unknown true incidence, it is prudent to be aware of it because early management of colloid cysts has a favorable outcome, in contrast to untreated cysts that are associated with higher rates of morbidity and mortality. Additionally, we provide a comprehensive, evidence-based review of the medical entity of intracranial colloid cysts with highlights of current postulated pathological theories and management algorithms.

On Natural History and Management of Colloid Cysts: Time to Rethink?

BACKGROUND

Colloid cysts, although benign, may occasionally cause obstructive hydrocephalus and sudden death. Reliable prognostic factors for symptomatic progression have been sought, with heterogenous results.

METHODS

We conducted a retrospective review of all cases of colloid cysts of the third ventricle managed at our center between 2009 and 2019. Clinical and neuroimaging characteristics were analyzed using logistic regression in relation to symptomatic status and hydrocephalus. The cutoff values for outcome prediction were calculated using the receiver operating characteristic curve analysis.

RESULTS

There were 82 patients with colloid cysts, of whom 60 were asymptomatic and 22 symptomatic. None of the asymptomatic patients experienced acute neurologic decline or hydrocephalus during follow-up, whereas half (n = 11) of the symptomatic patients presented with hydrocephalus, 8 of whom had acute hydrocephalus. We found 3 putative candidate risk factors for symptomatic colloid cysts: T1-weighted magnetic resonance imaging hyperintense/mixed signal appearance (P = 0.004), location in risk zone I (P = 0.007), and a volume >236.49 mm3 (P = 0.007). Cyst diameter and volume/foramen of Monro diameter ratios had a decreasing trend over time among asymptomatic patients, providing new insights into the natural history of the disease.

CONCLUSIONS

Only a few asymptomatic colloid cysts showed progression requiring surgery, with no acute deterioration or fatal events, whereas the rest remained stable over time, thus supporting a more conservative approach for this group of patients. Higher risk for developing symptomatic colloid cyst was defined by a risk score that included T1-weighted magnetic resonance imaging appearance, risk zone, and colloid cyst volume, aiding the detection of patients at risk of clinical deterioration.