Clinical image:

A 36-year-old woman presented with an asymptomatic eruption of multiple pink umbillicated papules in the left part of trunk and under the umbilical area. There was no history of systemic or skin disease, use of local or systemic immunosuppressive drugs, or suspect sexual contact. She reported similar eruption in her child. Dermatologic examination revealed multiple linear shiny papules in the left part of trunk measuring approximately 4 to 20 mm. (Fig. 1a-b). Dermoscopy revealed a polylobular, pinkish-white, amorphous structure in the centre with a surrounding crown of vessels that did not cross the centre of the lobule (Fig. 2).

The diagnosis of MC was evoked. The patient was treated by potassium hydroxide 5% twice resulting in complete healing in 2 weeks.

Our case illustrated an atypical presentation of MC in immunocompetent adult. Although recognized nearly 200 years ago, MC still causes a substantial health-care burden and adversely affects quality of life.

Clinically it appears like shiny papules with a diameter between 2 and 5 mm. The central umbilication is pathognomonic and its localization concern commonly the face, trunk, and extremities. ¹

Although easily diagnosed, MC may present as a single lesion or as several small, inflamed lesions of difficult diagnosis. Atypical presentations may occur in immunodepression condition, eczematous or abscessed and sometimes refractory to the usual treatment.²

To the best of our knowledge, we report the third case of linear MC. In our patient, the diagnostic was evocated based on the presence of similar case in the family, clinical characteristics of the lesions and confirmed by the typical dermoscopic features.