Introduction:
Reactive arthritis (ReA) is one of the forms of seronegative spondyloarthropathies. The difficulties in the diagnosis of reactive arthritis, despite a complex clinical picture, result from the lack of unequivocal diagnostic criteria, especially in the initial period. Diverse clinical manifestation of ReA may require the cooperation of many specialists.

Aim:
The case of a 59-year-old man with reactive arthritis caused by an acute Yersinia enterocolitica infection 3 weeks before was described.

Case study:
A 59-year-old patient, so far healthy, was admitted due to fever for a few days, pain and swelling of crurotalar joints, pain in the left part of the lumbosacral region, escalating at night, and additional complaints impeding urinating. Joint involvement was accompanied by numerous cutaneous and mucosal lesions.

Results and discussion:
In this case the presence of characteristic cutaneous symptoms as keratoderma blenorrhagicum and balanitis circinata allowed to identify the disease quickly, despite a short course of the disease. The presence of antibodies of Y. enterocolitica IgA was noticed, without the presence of IgG and IgM. The presence of HLA B27 antigen was positive. In this case, the occurrence of many characteristic cutaneous lesions enabled a quick identification of the disease, despite the difficulties with determining the etiological factor.

Conclusions:
The diagnosis of ReA is clinical, based on the history and physical examination findings. A high index of suspicion is required because no laboratory tests, markers or imaging finding allow diagnosing of ReA. The most important is proper cooperation between a rheumatologist and a dermatologist.