Recurrent neutrophilic panniculitis secondary to bacterial cystitis

Neutrophilic panniculitis (NP) is a widely unknown inflammatory disorder of the subcutaneous fat. The diagnosis and proper classification of panniculitis relies on histologic features, mainly the location of the subcutaneous inflammation (septal, lobular, mixed or vascular). In contrast to erythema nodosum, where the inflammation predominates in the fat septa, NP is localized in the fat lobules. However, little is known about this rare condition. We report a 54-year-old woman with a history of several episodes with subcutaneous nodules occurring on the lower legs secondary to bacterial cystitis (successfully treated with antibiotics prior to admission to our Department), that responded immediately to treatment with oral corticosteroids. An infective aetiology for NP has not been described so far, although this can be found in other neutrophilic dermatoses. The originality of our case is the recurrence of the disease on several occasions in association with bacterial cystitis. This case confirms that infections can be a cause of NP.