Nicolau syndrome following intramuscular diclofenac administration: a case report.

Nicolau syndrome (livedoid dermatitis) is a rare adverse reaction of a still largely unidentified pathogenesis at the site of intramuscular drug injection. The typical presentation is pain around the injection site soon after injection, followed by erythema, livedoid patch, haemorrhagic patch, and finally necrosis of skin, subcutaneous fat, and muscle tissue. The phenomenon has been related to the administration of a variety of drugs, including non-steroidal anti-inflammatory drugs, corticosteroids, and penicillin. We report a case of Nicolau syndrome following an intramuscular injection of diclofenac. The large ulceration over the right buttock was positive for Pseudomonas aeruginosa, and histology revealed subcutaneous fat necrosis and non-specific inflammation with no evidence of malignancy or vasculitis. The lesion required multiple debridements and a partial-thickness skin graft. Subcutaneous injection, rather than intramuscular injection, was found to be a determining factor in this case. Clinicians must be cautious in the use of proper injection procedures, including appropriate needle length, in order to minimise complications.