Solitary bone plasmacytoma as posterior fossa cranial neoplasia, presentation of two clinical cases.

Background: Solitary bone plasmacytoma is a plasmatic cell dyscrasia; its presentation in the posterior fossa is very rare.

Case Description: We present two cases, a 59-year-old male and a 50-year-old female, both with heterogeneous clinical presentation. One had symptoms compatible with endocranial hypertension, and the other presented with a hemispheric cerebellar syndrome and ipsilateral trigeminal neuralgia.

Bobble-head doll syndrome in an 80-year-old man, associated with a giant arachnoid cyst of the lamina quadrigemina, treated with endoscopic ventriculocystocisternotomy and cystoperitoneal shunt.

Bobble-head doll syndrome (BHDS) is a rare entity, characterized by antero-posterior head bobbing, which is of the type "yes-yes." Less frequently, having a head movement of the type "no-no" is described. We report an unusual case of an 80-year-old man with a cystic mass of the lamina quadrigemina, extending to the posterior fossa.