Massive leptomeningeal amyloidosis associated with a Val30Met transthyretin gene.

We report a 69-year-old woman of Mexican origin with a 6-year history of progressive paresis, mild peripheral neuropathy, and recent onset of fluctuating mental status. Head and spinal MRI revealed contrast enhancing thickened meninges which on biopsy disclosed amyloid deposition. Immunohistochemistry identified the amyloid as transthyretin (TTR), and polymerase chain reaction/restriction fragment length polymorphism analysis of blood revealed a Val30Met mutation in one of her TTR genes. This mutation causes familial (hereditary) amyloidotic polyneuropathy of the Portuguese type (FAP 1). However, unlike FAP 1, in which peripheral neuropathy is a dominant feature, our patient's clinical manifestations, which included communicating hydrocephalus and myelopathy, were more suggestive of familial oculoleptomeningeal amyloidosis (FOLMA). In summary, the clinical presentation of TTR Met 30 mutation is more varied than previously suspected, and leptomeningeal amyloidosis should be considered in the differential diagnosis of obscure conditions involving meninges.