Confocal laser scanning microscopy, a diagnostic alternative for five pigmented lesions on the face: An observational study.

OBJECTIVE: To describe the confocal laser scanning microscopy (CLSM) features of five different facial hyperpigmentation diseases and to highlight the features that can be used to differentiate between the diseases.

MATERIALS AND METHODS: Confocal laser scanning microscopy features of skin lesions of 406 patients with different facial hyperpigmentation diseases (chloasma, naevus fusco-caeruleus zygomaticus, naevus of Ota, freckles and Riehl melanosis) were retrospectively analysed. All patients were diagnosed clinically. The features of each layer of the skin in the involved regions and at the junction of the lesion with normal skin were studied, and the characteristic features of each disease were identified. The CLSM probe was applied perpendicular to the skin surface. Scanning was performed with medical ultrasonic coupling agent applied between the adhesive window and skin and between the lens and adhesive window. The skin was scanned layer by layer, and the best cross-sectional images were stored in the computer for analysis.

RESULTS: Chloasma lesions showed significantly increased pigment content in the epidermal basal layer and, in some cases, varying degrees of pigment particle deposition in the upper dermis. Naevus fusco-caeruleus zygomaticus and naevus of Ota lesions showed normal epidermal pigment content, with cord-like high-refractive pigment masses scattered in the dermis; cord-like or dendritic melanocytes were seen between collagen fibre bundles in the upper and middle dermis, but no inflammatory cell infiltration was seen. Freckles lesions showed increased numbers of pigment particles in the basal layer, but no abnormal changes in the dermis. Riehl melanosis was characterised by liquefaction degeneration of the basal cells, accompanied by considerable monocyte and melanophage infiltration in the dermal papilla.

CONCLUSIONS: Used in combination with clinical manifestations, CLSM can be a useful auxiliary method for diagnosis of naevus fusco-caeruleus zygomaticus, naevus of Ota, chloasma, freckles and Riehl melanosis.