Unmasking Facial Melanosis

INTRODUCTIONVarious entities of acquired facial melanosis present with considerable clinical overlap, posing diagnostic challenges. Dermoscopy is being increasingly used in its diagnosis.

OBJECTIVESTo assess dermoscopic and clinicopathological features of facial melanosis in Fitzpatrick skin types IV-VI.

METHODSA prospective cross-sectional study of clinical and dermoscopic features of facial melanosis-lichen planus pigmentosus (LPP), pigmented contact dermatitis (PCD), and facial acanthosis nigricans (FAN)-was conducted. Melasma, periorbital hyperpigmentation, and nevus of Ota were excluded.

RESULTSFifty-six patients were included: 31 (55.4%) with LPP, 18 (32.1%) FAN, and seven (12.5%) PCD. Clinically, LPP showed significantly more involvement of face (55.2 ± 22.2%) (P=0.029), especially the chin (29, 93.5%) (P=0.006). Dermoscopy revealed more than one pattern of pigment structures in 54 (96.4%) patients. Predominant patterns in LPP were reticular (21, 67.7%), peppered (15, 48.4%), and annular (13, 41.9%). There was an overlap of patterns like annular, annular-granular, and reticular in both LPP and PCD. Peppered (15, 48.4%) was significantly more in LPP (P=0.023), while linear dots were seen exclusively in LPP (4, 12.9%); smudged was significantly more in PCD (6, 85.7%) and FAN (15, 83.3%) (P=0.003). Concentric circles (16, 88.9%) and parallel lines (14, 77.8%) were significantly more in FAN (P<0.001 each), while crypts-gyri (10, 55.6%) and papillary projections (8, 44.4%) were seen exclusively in FAN. Combination of dots and clods was also significantly more in LPP (26, 83.9%; P=0.007), whereas blue-gray pigmentation (19, 61.3%) was observed exclusively in LPP.

CONCLUSIONDistinct dermoscopic features aid in differentiating acquired facial melanosis. Blue-gray dots and clods in peppered, reticular, and linear dots patterns favor LPP, while concentric circles, parallel lines, crypts-gyri, and papillary projections suggest FAN. Recognition of these patterns may obviate biopsy in cosmetically sensitive areas.

Abstract from PubMed