Hereditary nonpolyposis colorectal cancer (HNPCC), also known as Lynch syndrome, is a common autosomal dominant syndrome characterized by early age at onset, and microsatellite instability (MSI). Patients with Lynch syndrome have a markedly increased risk of colorectal cancer. We report a case of a 28-year-old male with Lynch syndrome; the case allows to describe clinical manifestations and diagnostic criteria of this syndrome, and to underline the importance of genetics in the diagnosis of this disease
