A 28-year-old white urology resident presented with an asymptomatic oval brown patch on her nose, allegedly present for less than 3 hours (Figure). She denied any antecedent factors such as contact with a foreign substance. She had rubbed the lesion repeatedly with an alcohol wipe without clearance. On examination, she was found to have a 1.5-cm light brown, well-defined patch on the right nasal ala in addition to myriad lentigenes on the forehead, nose, and cheeks. Despite the reported duration of the lesion, the differential diagnosis included lentigo, postinflammatory hyperpigmentation, and discoloration secondary to chemical contact.
Abdulla FR, Adams BB. Ortho-Phthalaldehyde Causing Facial Stains After Cystoscopy. Arch Dermatol. 2007;143(5):659-675. doi:10.1001/archderm.143.5.670-a