Neutrophilic lobular (pustular) panniculitis associated with rheumatoid arthritis - A case report and review of the literature

Rheumatoid nodules, which affect the subcutis around joints, are the most f requent specific cutaneous lesions of rheumatoid arthritis (RA). Panniculit is is a rarely reported and nonspecific complication of RA. We report a 42- year-old woman with seropositive RA who presented with a 2-month history of lower leg panniculitis. Biopsy of a leg nodule showed a lobular neutrophil ic infiltrate with lipophages and central basophilic necrosis. In addition, focal changes of lipomembranous fat necrosis indicative of ischemic damage were identified at the margins of the lobular infiltrate. Neutrophilic lob ular panniculitis is commonly detected in panniculitis secondary to bacteri al infections, pancreatitis, and factitial causes. However, this pal tern o f panniculitis has also been reported in some cases of erythema nodosum-lik e lesions found in Behcet disease or bowel bypass syndrome and in rare case s of seropositive RA. These reported histologic findings fall into the spec trum of neutrophilic vascular reactions described by Jorizzo and Daniels fo r RA-associated dermatoses. In view of these findings, RA and related neutr ophilic dermatoses (e.g., Behcet disease) should be included in the differe ntial diagnosis of neutrophilic lobular panniculitis.