Clinical, Dermoscopic and Histopathological Study of Patchy Pigmentation of Lower Legs

Patchy pigmentation of lower legs presents with patches of hyperpigmentation, hypo, or depigmentation of legs. Dermoscopy is an efficient diagnostic tool dermatologists use to bridge the clinical and histological evaluation gap. This study on lower leg pigmentation is probably the first report from India.

To study the clinical, dermoscopic, and histopathological features of patchy pigmentation of lower legs in patients presenting to our Out-Patient Department (OPD).

This was a cross-sectional descriptive study done on 150 patients with patchy pigmentation of lower legs in patients above the age of 18 years attending the dermatology OPD, JIPMER, during the study period of March 2022 to December 2023 by convenient sampling. A detailed history was taken and a detailed dermatological examination was performed. Dermoscopy and skin biopsy for histopathological examination was performed and recorded in a proforma.

The mean age of the cases was found to be 52.3 (±14.06) years (ranged from 18 to 97 years) with female:male ratio of 1.7:1. Among 150 cases, 127 (84.66%) cases had patchy hypopigmentation and 23 cases (15.33%) had patchy hyperpigmentation of lower legs. Among 127 cases of patchy hypopigmentation of lower legs, idiopathic guttate hypomelanosis (IGH) was the most common cause found in 61 (48.81% cases), followed by vitiligo (32, 25.19% cases), and post-inflammatory depigmentation (29, 22.65% cases). Among 23 cases of patchy hyperpigmentation of lower legs, pigmented purpuric dermatosis (PPD) was the most common cause seen in 12 (52.17% cases), followed by post-inflammatory hyperpigmentation (10, 43.47% cases). The most common dermoscopic pattern was amoeboid (21, 33.87%) in IGH, white structureless areas (31, 96.9% cases), followed by perifollicular pigmentation (18, 56.3% cases) in vitiligo and red dots (10, 83.3%) in PPD.

Nearly 85% of lower leg pigmentation cases were hypopigmentary. Amongst hypopigmentary disorders, nearly 50% of cases were of idiopathic guttate hypomelanosis, followed by others like vitiligo, post-inflammatory depigmentation, contact leukoderma, nevus depigmentosus, and hypopigmented macular amyloidosis. Dermoscopic features of vitiligo and post-inflammatory depigmentation were similar. Pigmented purpuric dermatosis was the most common cause of hyperpigmentary disorders of the lower legs, followed by post-inflammatory hyperpigmentation and macular amyloidosis.