Colloid cyst with hyphal-like structures: A rarity that mimics actinomycosis of athe third ventricle.

Colloid cysts are histologically well defined and consist of three main components, a capsule, with an underlying epithelial layer, and a mucinous heart. In our case, we present a 35-year-old female with acute deterioration of level of consciousness. An emergent CT scan showed a cystic lesion occluding the intraventricular foramen. The lesion was endoscopically excised through a transfrontal approach. Microscopic examination of the resected specimen revealed hyphal-like structures (HLS). This rare finding was first described by Dodds and Powers in 1977 and, in its microscopic nature, it mimics actinomyces of the third ventricle.