MedicineToday x DECEMBER 2014, VOLUME 15, NUMBER 12 65 PERSPECTIVES ON DERMOSCOPY MedicineToday PEER REVIEWED A pigmented macule on the nose What is your diagnosis? HELENA COLLGROS MD PASCALE GUITERA MD, PhD, FACDS The differential diagnosis of pigmented macules of the face can be challenging. Dermoscopy may help, and adding confocal microscopy improves sensitivity and specificity; histopathology, however, remains the gold standard. CASE PRESENTATION A man in his 60s presented for a full skin check. He had heavily sun-damaged skin and a past history of lentigo maligna on the nose that was treated three years ago with cryotherapy and imiquimod. He had noted some new pigmentation arising in that area. On clinical examination, an irregular pigmented macule of two colours was seen (Figure 1). Differential diagnoses included solar lentigo, flat seborrhoeic keratosis, pigmented actinic keratosis and, most importantly, recurrent lentigo maligna. Dermoscopic examination showed homogeneous light brown pigmentation, asymmetrical hyperpigmented follicular openings, granular blue-grey pigmentation and rhomboidal structures (Figures 2a to c). As the borders of the lesion were very uneven, an in vivo reflectance confocal microscope (RCM) was used to confirm the diagnosis and map the area to treat (Box). The RCM image of the epidermis showed multiple atypical large bright round cells (Figure 3), a characteristic feature for pagetoid spread. (Pagetoid cells are cells, melanocytes in this case, that invade the upper epidermis from below. In RCM, they are seen as large bright round cells or as pleomorphic cells with dendritic pro- cesses.) A biopsy was performed and the pathology report Dr Collgros is a Dermatologist in the Dermatology Department, Hospital Universitari Germans Trias i Pujol, Badalona, Spain. Dr Guitera is a Dermatologist at the Melanoma Institute Australia, Sydney; Director of the Sydney Melanoma Diagnostic Centre at Royal Prince Alfred Hospital, Sydney; and a Senior Researcher in the Department of Dermatology at The University of Sydney, Sydney, NSW. Figure 1. Lentigo maligna. The irregular pigmented macule of two colours on the left side of the patient’s nose. MedicineToday 2014; 15(12): 65-68 Downloaded for personal use only. No other uses permitted without permission. © MedicineToday 2014.