Sudden Appearance of Pin-point Hyperpigmented Macules: Dermoscopy Saves the Day.

Sir,

A 22-years-old girl presented with sudden appearance of asymptomatic minute black spots over the right forearm of one day duration. On examination, there were multiple hyperpigmented pin-point macules on the extensor aspect of right forearm [Figure 1]. A detailed history revealed that the patient noticed the lesions immediately after finishing her chemistry practical class where she had handled sulphuric acid. She had used gloves extending up to the wrist. She did not recall spilling the acid on her hands or forearms and did not give any history of burning sensation. Dermoscopy with “DIGI-MICROSCOPE”® at 50x magnification showed a targetoid pattern with central normopigmented area surrounded by an irregular hyperpigmented band of varying width. The inner border of the hyperpigmented band was well-demarcated and serrated while the outer edge gradually merged into the surrounding normal skin with outward radial spikes along the skin creases [Figure 2]. This was suggestive of necrosis of the skin with loss of the central necrotic area leaving behind irregular necrotic edges. The outward radial spikes could have been due to flow of some corrosive liquid along the skin creases which had caused the necrosis of the skin. This dermoscopic picture alongwith the history of exposure to sulphuric acid indicated that this was a case of sulphuric acid burn. She was prescribed topical 2% mupirocin. There was complete resolution of lesions on the 7th day follow-up.

Figure 1

Hyperpigmented pin-point macules over the forearm

Figure 2

Dermoscopic view (50x) showing targetoid pattern with outward radial spikes

The popularity of dermoscopy has increased in India in the past decade. Apart from melanocytic nevi and melanoma, traditional indications in the western world, it has been used in the diagnosis and study of myriad conditions including psoriasis, lichen planus, dermatofibroma, Darier's disease, seborrheic keratosis and urticarial vasculitis.[1] Dermoscopy has been extensively used to analyse types of scarring and non-scarring alopecia, hair shaft disorders[2] and other hair disorders.[3] It has proven useful in analysis of hyperpigmented lesions in the brown skin like Cafι-au-lait macules, lichen planus pigmentosus, post-inflammatory hyperpigmentation, Becker's nevus, melasma, exogenous ochronosis, pigmented purpuric dermatoses with different pigment patterns like granular pigment network, blotches, reticuloglobular and annular pattern.[4] Sulphuric acid causes coagulative necrosis and discoloration of tissues producing the targetoid pattern with radial spikes on dermoscopy. This report highlights the importance of dermoscopy in apparently non-specific, difficult to diagnose skin lesions and adds to the list of indications of dermoscopy.