A cross sectional descriptive study of dermoscopic features of clinical variants of cutaneous tuberculosis

Tuberculosis continues to be a major public health concern worldwide with almost 20-40% of the world's population being affected yearly. Cutaneous Tuberculosis (TB) is a rare and underdiagnosed entity that manifests in about 1-1.5% of extrapulmonary tuberculosis cases worldwide. Dermoscopy is a non-invasive tool which will be a useful aid to histopathology in the confirmation of the diagnosis alongside culture, and molecular techniques. This is a cross-sectional descriptive study that was conducted at a tertiary care center in Mumbai, India. A total of 31 patients were enrolled in this study; 14 males and 17 females. The mean duration of disease was 4.3 months and the average age was 31 years. There were 10 cases of lupus vulgaris, 7 scrofuloderma, 5 papulonecrotic tuberculid (PNT), 3 tuberculosis verrucosa cutis (TBVC), and 2 cases each of erythema induratum of Bazin, lichen scrofulosorum and resolved lupus vulgaris. All the lesions demonstrated orange yellow background suggestive of dermal granuloma. Other key dermoscopic features noted include yellowish-white scales, patulous follicles, white structureless areas, milia-like cysts, white streaks, pigment globules, hairpin and linear vessels. Newer findings such as the crown of vessels and perifollicular pallor in lichen scrofulosorum, and radiating white streaks in PNT were also noted. Dermoscopy of infective granulomas such as cutaneous tuberculosis is a less explored field of dermatology. Newer dermoscopic features of each clinical variant of cutaneous TB have been described.