| The Familial
Adenomatous Poliposis (FAP) is a rare autosomal
dominant disease in which appears numerous adenomatous
polyps in the colon and rectum.
The polyps can appear already in the childhood
but to the 30-40 years of life exists hundreds
of them, between 500 and 2500, occupying all the
length of the large intestine until the rectum.
For the diagnosis of this disease it is necessary
to find a minimum of one hundred polyps. The size
of the polyps oscillates between few millimeters
and several centimeters of diameter, and frequently
they appear covering the entire mucous surface
with the large intestine.
Histologically the polyps are adenomas (benign
epithelial neoplasms derived from glandular epithelium
of the large intestine), most of them are tubular
type adenomas, although it also can have villous,
indistinguishable adenomas histologically of the
sporadic solitary adenomas (non-hereditary).
Nevertheless, unlike which it happens in the
solitary adenoma, practically in the totality
of the cases of the hereditary disease, one or
more of the adenomas (adenomatous polyps) they
finish transforming itself into adenocarcinoma,
frequently multiple, before the 45 years of life
and some patients have adenocarcinoma already
when the disease is diagnosed.
The disease is due to a deletion or inactivation
of a suppressor gene of tumors denominated APC
(gene of the familial adenomatous poliposis),
located in the long arm of chromosome 5 (5q21).
At the moment one knows that protein APC (codified
by this gene) is an inhibiting component of the
route of signaling of Wnt. Wnt joints the beta-catenin,
another component of the route, and then it prevents
the activation of TCF4, a regulating protein of
genes that stimulates the cellular proliferation
when it is united to beta-catenin. These mutations
can be detected with programs of precocious detection
before the polyps form. The development of the
cancer can only come up by means of constant monitoring
with resection of the entire colon when it is
necessary.
Author:
Tomás Castiella Muruzábal
Servicio de Anatomía Patológica
Hospital Clínico Universitario “Lozano
Blesa”
Zaragoza
English translation by Lalit
Kumar |
