Each time this 32-year-old woman has a baby—she’s had four to date—she notices that sections of her face darken. Early on, she observed a pattern in which the coming of winter coincided with a lightening of these affected areas—but now the effect lasts year-round, with progressive darkening. She has not tried any products (OTC or prescription) for this problem.
Growing up in the South, the patient and her family spent most summers boating, swimming, and fishing. Her use of sunscreen was sporadic, but she would tan easily regardless.
Her health is good, aside from a 15-year history of smoking.
There is excessive hyperpigmentation (brown) on the patient’s face. It follows a mask-like pattern, including her maxilla and the periphery of her face.
Elsewhere, there is abundant evidence of excessive sun exposure, with focal hyperpigmentation and telangiectasias on her arms. She has type IV skin, consistent with her Native American ancestry.
What is the diagnosis?