On further questioning, the patient denied episodes of blurred vision and blunt ocular trauma. She was unable to recall any periods of significant ocular redness or treatment for infection.
Given the clinical findings, the differential diagnoses are not limitless. These diagnoses involve disturbance of the retinal pigment epithelium (RPE). Considerations include post-inflammatory/infectious, post-traumatic, and congenital (e.g., congenital hypertrophy of RPE [CHRPE]) entities.
Related: Eye punch leads to choroidal rupture
In the absence of a history of trauma, the field narrows. Choroidal nevus emerges in the realm of pigmented fundus lesions but would be ruled out by the persistence of the pigmented lesion in its entirety when viewed with red-free light.
Whether the fundus appearance is due to CHRPE or a post-inflammatory scar, there is little that would alter observation about the clinical course. With the exception of a recurrence of a toxoplasmosis lesion, standard vigilance is appropriate with admonition regarding floaters and blurred vision, potentially indicative of reactivation. The patient was questioned specifically regarding the risk pool for toxoplasmosis exposure—all of which she denied.
Follow-up exam and diagnosis
The patient was seen at the same clinic five years later for follow-up. The history and physical findings were unchanged. The exception was the appearance of the peripheral lesion that was observed at the initial visit (see Figure 2).
With the depigmentation of the lesion evident, it became clear that the diagnosis is CHRPE. These lesions are generally round and demonstrate a halo of atrophy, hence the moniker “halo nevus” used incorrectly by some. Another distinct example of a solitary CHRPE lesion is shown in Figure 3.1
As the clinical descriptor suggests, these lesions are present at birth. Variations have been associated with familial adenomatous polyposis (FAP).2,3,4