A 44-year-old white man presented with a 12-month history of slightly pruritic, papular lesions on his face, upper and lower extremities. No other complains were mentioned. No similar skin dermatosis was reported from his family history including first-degree relatives. The patient had no history of kidney disease, diabetes mellitus or liver disease.

Physical examination was unremarkable except for the skin findings. Specifically, skin lesions were 8 in number located on the middle of the chin, on the right angle of the mouth and on the extensor surfaces of the forearms, elbows, thighs and knees. There was no mucous membrane involvement. Skin lesions were characterized by areas with diameter of 1 cm up to 8 cm consisting of multiple hyperkeratotic plaques and burrows. The large and old lesions of the extremities did not have signs of inflammation (Figure 1). In contrast, the small and new lesions on the face had clear signs of ongoing inflammation with an erythematous halo surrounding them (Figure 2). Mild tenderness and increased temperature was also evident on the face skin lesions.

Testing for anti-nuclear and anti-mitochondrial antibodies was negative, but it was weakly positive for anti-smooth muscle antibodies. There was also a slight elevation of the level of the haemolytic complement [CH50 = 556 U/ml (normal 300-510 U/l)]. The levels of the third and fourth component of complement (C3 and C4) were normal. Finally, a serologic test for syphilis [Venereal Disease Research laboratory (VDRL) slide test] was negative.