Adult‐Onset Partial Unilateral Lentiginosis: A Rare Pigmentary Mosaicism With Clinical Response to Tranexamic Acid

Partial unilateral lentiginosis (PUL) is a rare pigmentary disorder characterized by numerous lentigines grouped within normal skin in a segmental pattern with sharp demarcation at the midline. The authors hereby present a case of a 40‐year‐old female, who presented with multiple asymptomatic, gradually progressive, brownish flat skin lesions on her left breast, abdomen, and left half of the trunk for 16 years. Diagnosis was made clinically via properly documented history, physical examination, and histopathological evaluation. Although treatment is unnecessary, many patients seek consultations for cosmetic reasons. Our patient is showing a good response to the prescribed tablet tranexamic acid and topical kojic acid cream, along with regular application of sun protection cream SPF 50+. This is a rare case of adult‐onset PUL showing good clinical improvement with oral tranexamic acid combined with kojic acid cream.