Xanthogranulomatous colloid cyst: Radiologic- pathologic correlation and diagnostic difficulties.

Background: Despite colloid cyst in the third ventricle is a very usual cause of hydrocephalus, its xanthogranulomatous variant is rare. The most important differential diagnosis is the third ventricular craniopharyngioma. To the best of the authors' knowledge, there have been few cases of xanthogranulomatous variant colloid cysts reported in the English literature.

Case Description: A 77-year-old white woman presented with headaches, memory loss, and abnormal gait for the past 4 months. Magnetic resonance imaging revealed a solid cystic lesion measuring 3.0 cm×2.8 cm×2.9 cm located inside the anterior portion of the third ventricle causing obstructive hydrocephalus. The posterior portion of the lesion was predominantly solid and hypointense on T2 and T1, with areas of post- contrast enhancement, and the anterior portion was predominantly cystic with both hyper- and hypointense areas on T1 and T2, with no suppression on fluid-attenuated inversion recovery and no restriction to diffusion. The patient underwent a left frontal craniotomy with pterional approach, and the lesion was removed microsurgically.

Conclusion: Xanthogranulomatous reaction is rarely described in colloid cysts, which happens as a response to desquamation of epithelial lining, subsequent lipid accumulation, and as tissue inflammatory response to intracystic hemorrhage. Microsurgical resection is the treatment of choice. As compared to the plain colloid cyst, these lesions are difficult to fully excise as the inflammatory reaction to the xanthomatous material leads to adhesions to adjacent structures; therefore, the aspiration of cystic contents without spillage is advisable to achieve maximal resection of cyst walls.