Presenile Alzheimer dementia characterized by amyloid angiopathy and large amyloid core type senile plaques in the APP 692Ala-->Gly mutation.

Mutations at codons 717 and 670/671 in the amyloid precursor protein (APP) are rare genetic causes of familial Alzheimer's disease (AD). A mutation at codon 693 of APP has also been described as the genetic defect in hereditary cerebral hemorrhage with amyloidosis of the Dutch type (HCHWA-D). We have reported a APP692Ala-->Gly (Flemish) mutation as a cause of intracerebral hemorrhage and presenile dementia diagnosed as probable AD in a Dutch family.

Signet-ring cell oligodendroglioma--report of two cases and discussion of the differential diagnosis.

Two cases of oligodendroglioma consisting largely of signet-ring cells were analyzed histopathologically, immunohistochemically and at the ultrastructural level. The signet-ring cells were negative for a panel of tumor lineage markers including glial fibrillary acidic protein, and were negative for Ki-67 (MIB-1 immunohistochemistry). In contrast with the abundance of lysosomal structures reportedly present in the so-called eosinophilic granular cells in oligodendrogliomas, degenerating mitochondria were mainly seen in the cytoplasm of the signet-ring cells.

Cytogenetic, molecular genetic and pathological analyses in 126 meningiomas.

In a series of 126 meningiomas, tumor and patient characteristics were investigated and statistically analyzed. A combined cytogenetic and molecular genetic approach was used to study chromosomal abnormalities and loss of markers on chromosome 22q. This approach was successfully applied to 93 meningiomas.

Familial occurrence of polymorphous oligodendroglioma.

A case of familial polymorphous oligodendroglioma, occurring in a brother and sister, is presented. Polymorphous oligodendrogliomas have a characteristic histopathology consisting of scattered multinucleated giant cells against a typical oligodendroglial background. The oligodendroglial character of the tumors was underlined by positive immunostaining for antigalactocerebroside, anticarbonic anhydrase, and anti-leu-7, without expression of glial fibrillary acidic protein.

Nasopharyngeal presentation of pituitary tumors. Differential diagnosis and treatment.

The intranasal presentation of pituitary tumors is rare. We describe six patients with supposedly intranasal carcinomas, treated by surgery, local chemotherapy, and/or radiotherapy. Because of the favorable clinical course, immunohistochemical reexamination of tumor tissue was done, which showed a macroprolactinoma in four and a nonfunctioning pituitary adenoma in two patients.