Occasionally, linear depigmented streaks and localized zones of mild hyperpigmentation occur at the anterior margin of these lesions. Although most of these lesions remain rather stationary, concentric enlargement has been demonstrated in up to 74–83% of cases ( Figure 12.01 H and I). These lacunae may show progressive enlargement, and eventually the entire lesion may become depigmented ( Figure 12.01 G). Hypopigmented or depigmented lacunae within these lesions are frequently evident, particularly in older patients ( Figures 12.01 B, D, E, and I, and 12.03 G and H). Although most CHRPE are between one and two disc diameters, some may occupy an area equal to one quadrant of the fundus ( Figure 12.01 B). There is often a halo of depigmentation just inside the outer edge of these lesions ( Figure 12.01 E and F). However, CHRPE in macula and juxtapapillary location are rare. A CHRPE may occur anywhere in the fundus. They are usually solitary but may be multiple and grouped in a pattern suggesting animal tracks ( Figure 12.01 A). Solitary-type CHRPEs are well-demarcated, slightly elevated, gray-brown to black, oval, round, or occasionally geographic lesions with smooth or scalloped margins ( Figures 12.01–12.03 ). Solitary-Type Congenital Hypertrophy of the Retinal Pigment Epithelium (CHRPE) Melanotic Nevi of the Retinal Pigment Epithelium It is important to realize that reactive proliferation of RPE, retinal glial cells, and retinal vascular endothelial cells can occasionally duplicate the clinical and histopathologic changes of all of the RPE hamartomatous lesions discussed in this chapter. Developmental uveal melanocytic nevi have been described in Chapter 14. A nevus is a “birthmark a circumscribed malformation of the skin, especially if colored by hyperpigmentation or increased vascularity it may be predominantly epidermal, adnexal, melanocytic, vascular, or mesodermal, or a localized overgrowth of melanin-forming cells arising in the skin early in life.” Ophthalmologists have adopted the term “nevi” to refer to developmental melanocytic lesions of the uveal tract, and it has been suggested as an appropriate term to describe developmental placoid lesions of the RPE. Stedman’s Medical Dictionary defines a hamartoma as: “a focal malformation that resembles a neoplasm grossly and even microscopically, but results from faulty development in an organ it is composed of an abnormal mixture of tissue elements, or an abnormal proportion of a single element, normally present at that site, which develops and grows at virtually the same rate as normal components, and is not likely to result in compression of the adjacent tissue (in contrast to neoplastic tissue).” A choristoma is defined as a “mass formed by maldevelopment of tissue of a type not normally found at that site.” Phacoma is defined as “a hamartoma found in phacomatosis,” a group of hereditary diseases characterized by hamartomas of multiple tissues. It appears that solitary CHRPE and congenital grouped pigmentation differ clinically from the multiple pigmented lesions seen with familial adenomatous polyposis and that patients with these conditions, as well as their relatives, are not at a greater risk of developing intestinal cancer.The terms “hamartoma,” “choristoma,” “phacoma (mother spot),” and “nevus” are used to describe benign developmental tumors or placoid lesions. This is much lower than would be expected from a survey of patients with the typical fundus lesions seen with familial adenomatous polyposis. Among more than 2000 of their blood relatives, only 20 had intestinal polyposis or colonic cancer (1%). Of the 132 patients with previously diagnosed CHRPE, there were none with familial adenomatous polyposis, Gardner syndrome, or intestinal cancer, and only one patient had a history of intestinal polyps. Patients and their physicians were contacted by telephone to complete a detailed questionnaire designed to detect signs or symptoms of familial adenomatous polyposis or Gardner syndrome among these patients with CHRPE and their relatives. Review of charts and follow-up studies were performed on all patients diagnosed and coded as having solitary CHRPE or its multifocal variant (congenital grouped pigmentation bear tracks). This study was undertaken to determine whether the typical lesions of CHRPE, seen frequently by ophthalmologists, also were indicators of familial adenomatous polyposis. Although atypical, such lesions have been called congenital hypertrophy of the retinal pigment epithelium (CHRPE). It has been recently documented that multiple bilateral pigmented lesions at the level of the retinal pigment epithelium may be an indicator of patients with familial adenomatous polyposis who are prone to develop intestinal cancer, particularly if there is a positive family history of these intestinal disorders.
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