Coexistence of two different intraspinal tumors. Case report and review of the literature.

The occurrence of multiple neoplasms in the central nervous system is well documented. In von Recklinghausen's disease, patients frequently present with multiple neurofibromas and/or meningiomas at different sites within the spinal axis. However, the presence of multiple, histologically different spinal tumors in the absence of von Recklinghausen's disease is extremely rare. The authors describe a patient with progressive paraparesis in whom an extradural, malignant lesion and a separate benign, intradural tumor of the thoracic spine were found. The histological diagnosis of the intradural tumor was a pigmented schwannoma. On review of the literature, the authors found nine additional cases of coexisting, histologically different tumors of the spine. The majority of these tumors occurred in the thoracic spine and, not unexpectedly, intradural meningiomas and schwannomas prevailed. Except for the presumed same mesenchymal cell origin of neurinomas and meningiomas, no explanation for the coexisting, different spinal tumors could be determined.

Tandem duplication of the epidermal growth factor receptor tyrosine kinase and calcium internalization domains in A-172 glioma cells.

Amplification and rearrangement of the epidermal growth factor receptor (EGFR) gene occur frequently in malignant gliomas. Rearrangement may also lead to the expression of potentially oncogenic EGFR deletion mutants. Data presented here indicate the existence of a 190 kDa mutant form of the EGFR in A-172 glioma cells that is substantially different from the deletion mutants characterized previously. The EGFR-like protein is expressed along with the 170 kDa wild type EGFR. It is detectable with antibodies to both extracellular and intracellular regions of the EGFR, but is not crossreactive with other HER-family members. The wild type and mutant receptors undergo phosphorylation in response to treatment with TGFalpha and are associated with expression of both 10.5 kb and 11.5 kb EGFR-related transcripts. Combined reverse transcription-polymerase chain reaction (RT-PCR) identifies a unique transcript in A-172 cells that encodes an in-frame, tandem duplication of both tyrosine kinase and calcium internalization (TK/CAIN) domains (exons 18 through 26). The duplication of these domains is associated with a specific genomic rearrangement between potential v-myb and c-myb consensus binding sites within introns 26 and 17 of the EGFR gene resulting in the formation of a chimeric intron.