Posterior fossa dermoid cysts causing cerebellar abscesses.

Dermoid cysts are uncommon tumors, and posterior fossa dermoid cysts may rarely cause abscess formation or formation of daughter abscesses within the cerebellum. At present, there are only 16 cases with posterior fossa dermoid cysts causing cerebellar abscesses reported in the literature. Two cases, 22 and 14 months old, with posterior fossa dermoid cysts and dermal sinus causing multiple cerebellar abscesses are reported. In the first one, there was also marked hydrocephalus. Retrospective examination of the patients revealed pinpoint-sized dimples in their suboccipital regions. Both patients were treated with antibiotics and underwent posterior fossa surgery. In the patient with marked hydrocephalus, ventriculoperitoneal shunting was performed after treatment of the infection. Both patients were neurologically normal, and there were no complaints, except a light learning difficulty in the patient with ventriculoperitoneal shunting, 133 and 34 months after surgery, respectively. Early detection of congenital dermal abnormalities along the craniospinal axis by routine examination of newborns is highly important before development of serious complications. Because surgery is the only effective treatment modality for these lesions, radical excision should be performed in all cases to avoid tumor recurrence. However, subtotal excision may be performed in selected cases, because the cyst capsule may adhere firmly to vital structures.