[A rare side effect of mesotherapy: Nicolau syndrome]

Nicolau's livedoid dermatitis is associated with drug-induced embolism in the cutaneous arterial bed, generally as a result of accidental intra-arterial injection. Herein, we report a case that is somewhat surprising because of its late onset following mesotherapy injections.

A 53-year-old man, with a history solely of tendinopathy for which he underwent mesotherapy sessions, consulted for livedoid lesions of the front of the knee with central necrosis. History-taking revealed a final course of mesotherapy three weeks earlier for patellar tendinitis below the left kneecap; intradermal injection of procaine and piroxicam had been unusually and intensely painful. The remainder of the clinical examination revealed additional livedoid lesions on the outside of the left ankle as well as purpuric lesions on the pads of the toes on the left foot. Laboratory tests revealed nothing of note. Skin biopsies of the livedoid circumference of the lesion showed arteriolar emboli of an amorphous material within the dermis obliterating the arteriolar lumen. The clinical appearance of skin lesions after mesotherapy led us to a diagnosis of Nicolau livedoid dermatitis.

Nicolau dermatitis is a rare skin complication described as occurring mainly as a result of intramuscular injections. The reported case is special because it comprises Nicolau dermatitis arising out of a session of mesotherapy employing an intradermal injection. However, there are only very few cases in which subcutaneous injections have induced Nicolau dermatitis. The pathophysiology is not well known, but several mechanisms are involved: arterial ischaemia by vasospasm or thrombosis. In this case, the semiotic appearance of the lesions and histological analysis militate in favour of accidental injection of a skin product into an arteriole, resulting in obliteration of the latter. Mesotherapy can induce Nicolau dermatitis.