Rheumatoid neutrophilic dermatitis: an initial dermatological manifestation of seronegative rheumatoid arthritis.

Rheumatoid neutrophilic dermatitis (RND) is an uncommon, but distinctive manifestation of rheumatoid arthritis (RA). We describe the case of a 35-year-old female who developed RND as an early stage of seronegative RA. Clinically, the lesions were presented by erythematous, slightly tender, papules, 5-10 mm in diameter, on the extensor surface of the left arm. The histopathological findings revealed a dense, dermal, mainly neutrophilic infiltrate, with prominent leucocytoclasia, but without any features of vasculitis. There was fibrinoid degeneration of collagen, resembling the collagen changes present in rheumatoid nodules in a miniaturized form. RND can be a reliable, early clinical sign of RA, as seen in our patient. Furthermore, this case demonstrates that RND may be associated not only with seropositive RA, as described in the literature, but also with seronegative RA, never before reported. The histological findings in our case are remarkable because of the fibrinoid collagen degeneration, which is described here for the first time in RND. Thus, RND may, in fact, be the initial phase of a spectrum that begins with a neutrophilic reaction and mild fibrinoid collagen degeneration, and evolves into rheumatoid nodules at the final stage.