Importance of retinal pigmentation as a subclinical marker in familial adenomatous polyposis.

Surgery was performed in 35 patients with familial adenomatous polyposis (FAP) from 22 family trees. To clarify retinal pigmentation as an important subclinical marker in patients with FAP, precise retinal examinations were performed in 41 cases (82 eyes), including 23 patients and 18 family members including 12 second-generation and third-generation possible carriers. In 27 patients, precise studies were done on accompanying lesions, and the number of polyps was counted at the time of surgery in each patient in every family tree. The overall incidence of retinal pigmentation in patients was 82.6 percent. The incidence of retinal pigmentation in possible carriers was found to be 50 percent, which is comparable with the calculated expressibility of the polyps. The shape and distribution of pigmentations were classified into two categories--large and small. A total of 1984 control retinal examinations were performed, which revealed only six retinal pigmentations (0.3 percent). In the control group, all pigmentation was solitary and unilateral. No large pigmentations in bilateral eyes were found in the control group. In large pigmentation, the sensitivity and specificity were calculated as 0.652 and 0.999, respectively, and in small pigmentation, the sensitivity and specificity were calculated as 0.783 and 0.997, respectively. Small pigmentation appears to increase in number around the age of the appearance of the polyp. Earliest recognition of the pigmentation in this series was one year of age.