A 32-year-old Indian woman (Fitzpatrick type IV) presents 4 months postpartum with progressive facial hyperpigmentation that began in the second trimester and worsened after sun exposure. On examination, she has symmetric reticulated brown patches involving the forehead, cheeks, nose bridge, upper lip, and chin—the pattern marked **A** in the diagram. She has no scale, erythema, or atrophy. Wood lamp examination shows enhancement of pigment borders indicating a predominantly epidermal component. Which of the following best describes the clinical significance of the distribution pattern marked **A**?