44495 Melanotic Macule: Unmasked

Background: A 60-year-old patient presented to the dermatology clinic with a complaint of brown spots in the oral cavity and around the lips, present for six years. The patient had a history of fallopian tube carcinoma for which she was taking olaparib, and a family history of Peutz-Jeghers syndrome. Physical examination revealed a right buccal mucosal lesion. Additionally, the hard palate and other buccal areas that were not visible to the patient were also found to have brown macules. Further evaluation revealed hyperpigmented macules on the upper and lower vermillion borders. Based on the clinical presentation the differential diagnosis included labial lentigines, Peutz-Jeghers syndrome, and Addison's disease. A shave biopsy was performed and submitted for histological evaluation. Microscopic examination revealed a prominent basal pigmentation of keratinocytes. Sox-10 demonstrated normal number of melanocytes. The sections showed increased pigmentation in the basal-cell layer and the lamina propria. The findings suggested a melanotic macule. The patient underwent colonoscopy and numerous intestinal polyps were identified, thus the patient was diagnosed with Peutz-Jeghers syndrome.