Fundus lesions of adenomatous polyposis

Abstract

Congenital hypertrophy of the retinal pigment epithelium (CHRPE) is the most frequent extraintestinal manifestation of familial adenomatous polyposis. Present in 70% of families with familial adenomatous polyposis, CHRPE is a highly reliable and early marker of the disease. Studies over the past 5 years have addressed the histologic characteristics of the pigmented fundus lesions, the definition of universal positive fundus criteria, and mostly the genotype-phenotype correlation. Indeed, the position of the mutation site of the APC (adenomatous polyposis coli) gene on chromosome 5 influences the retinal expressivity because CHRPE is present only if the mutation is located between exons 9 and 15. In CHRPE-positive families, fundus examination is simple, noninvasive, reproducible, inexpensive, and allows early detection of the mutant gene carriers. Knowing the CHRPE status of patients in a family with familial adenomatous polyposis helps to identify constitutional APC mutations. The combination of genetic analysis and fundus examination offers a 100% diagnostic predictability.

Congenital hypertrophy of the retinal pigment epithelium (CHRPE) in familial colorectal cancer

“…These do not have clinical significance in the context of CHRPEs and FAP. The wide variation in the reported incidence of CHRPE in the normal population (0.3-40%) [6][7][8][10][11][12][13] suggests that retinal pigmentation has often been misdiagnosed as CHRPE. We note that Hunt et al [9] had defined CHRPE as all pigmented fundus lesions, whether hypo-or hyper-pigmented, and they may have over-interpreted some pigmented lesions as being CHRPE.…”

“…The sensitivity of CHRPEs in FAP have been reported to range from 65 to 84% and the specificity greater than 94% [10,11,16,38]. In fact, some authors claim a 100% specificity when multiple bilateral CHRPEs are present [16].…”

“…CHRPE is a benign congenital abnormality of the retina and estimates of its prevalence in the normal population vary widely (0.3-40%) [6,[8][9][10]. In the general population, CHRPE is usually evident as a single, well demarcated hyperpigmented lesion.…”

“…But in some patients with FAP, CHRPE occurs as multiple bilateral lesions. The reported incidence of CHRPE in FAP kindreds ranges from 66 to 92% [6,[10][11][12][13].…”

“…1) [14,15]. Type A lesions are oval pigmented lesions with surrounding pale halo and are specific for FAP [10,11]. Type B lesions are small, round, pigmented and occur both in the general population and in patients with FAP, albeit as multiple bilateral lesions in FAP [10-13, 16, 17].…”