Purpose: To describe the longitudinal evolution of a solitary congenital hypertrophy of the retinal pigment epithelium lesion demonstrating progressive enlargement and increasing border irregularity over time. Methods: A single case was reviewed. Results: A 13-year-old boy presented with an evolving and enlarging congenital hypertrophy of the retinal pigment epithelium lesion over a 7-year period. Fundus images obtained when the patient was 7 years old showed a solitary, circular lesion with a hypopigmented center and mildly irregular, hyperpigmented borders that measured 1.5 mm × 1.5 mm. At age 13, the lesion had increased to 3.1 mm × 3.8 mm. Over the next 1.5 years, it enlarged further to 4.5 mm × 4.3 mm, accompanied by increasing irregularity and scalloping of the lesion borders. Conclusions: Although solitary congenital hypertrophy of the retinal pigment epithelium lesions are generally stable and asymptomatic, this case demonstrates that they may enlarge and become irregular over time. While most lesions remain benign with a good prognosis, regular monitoring is warranted to assess for atypical changes and potential malignant transformation.