Early-onset breast cancer in a Lebanese family with Lynch syndrome due to MSH2 gene mutation.

Background: There are still controversies about the integration of breast cancer as a part of the disease spectrum in Lynch syndrome.

Methods: A regular follow-up of a Lebanese pedigree with Lynch syndrome due to a point mutation of MSH2 gene at the splice donor site of intron 3 started in 1996.

Results: A 26-year-old pregnant woman, mutation carrier, developed an aggressive breast cancer, refractory to standard chemotherapy regimens.