Concomitant angiosarcoma and lymphoproliferative disorder in solid organ transplant recipients.

An increased risk of posttransplant malignancy has been consistently reported following various solid organ transplants. The malignancies most commonly encountered are non-melanoma skin cancers, carcinomas of lung or breast and posttransplant lymphoproliferative disorders. Angiosarcoma, an uncommon vascular mesenchymal neoplasm, is rare in the posttransplant setting. This report describes two patients who developed high-grade angiosarcoma following a solid organ transplant. Notably, in both patients, the diagnosis of angiosarcoma was preceded by diagnosis of a lymphoproliferative disorder with monoclonal immunoglobulin heavy chain rearrangement.

Methylation Abnormalities in Mammary Carcinoma: The Methylation Suicide Hypothesis.

Promoter silencing by ectopic de novo methylation of tumor suppressor genes has been proposed as comparable or equivalent to inactivating mutations as a factor in carcinogenesis. However, this hypotheses had not previously been tested by high resolution, high-coverage whole-genome methylation profiling in primary carcinomas. We have determined the genomic methylation status of a series of primary mammary carcinomas and matched control tissues by examination of more than 2.7 billion CpG dinucleotides. Most of the tumors showed variable losses of DNA methylation from all sequence compartments, but increases in promoter methylation were infrequent, very small in extent, and were observed largely at CpG-poor promoters. De novo methylation at the promoters of proto-oncogenes and tumor suppressor genes occurred at approximately the same frequency. The findings indicate that tumor suppressor silencing by de novo methylation is much less common than currently believed. We put forward a hypothesis under which the demethylation commonly observed in carcinomas is a manifestation of a defensive system that kills incipient cancer cells.