Olfactory hamartomas in tuberous sclerosis.

Gross or microscopic glial hamartomas were found in the anterior olfactory lobe and olfactory germinal layer of three babies, two of them newborns, with tuberous sclerosis. In two cases microscopic hamartomas were seen in the anterior olfactory lobe, and in one of them there was a prominent nodular tumor of the olfactory tract and trigone. In addition, in both of these cases there were bilateral germinal layer tumors between striatum and septum, at the junction of the obliterated olfactory recess and the frontal horn of the lateral ventricle. Only microscopic hamartomas were present in the olfactory germinal layer of the third case. Typical subependymal germinal layer tumors were also present elsewhere in all cases; however, cortical tubers were recognized in only two of them. In all three patients, the clinical presentation and death were due to cardiac rhabdomyomas. The findings suggest that olfactory hamartomas might be relatively common in tuberous sclerosis. Involvement of olfactory structures is not surprising because the lesions seem to originate in the germinal layer, a region of the brain which is prominently involved in the disease.