Pyoderma gangrenosum (PG) is a rare inflammatory disorder that may be a great masquerader in chronic wound diagnosis and treatment. PG is frequently misdiagnosed as venous insufficiency, arteriosclerosis, bacterial or fungal infection, or even vasculitis. The most common clinical variant is its ulcerative form, mainly found on lower legs. In many cases, PG may coexist with other inflammatory disorders like ulcerative colitis, Crohn’s disease, or rheumatoid arthritis. The aetiopathogenesis is unclear, but the immunological system plays a key role. We present a 59-year-old patient treated for several years for a venous ulcer that was finally diagnosed with pyoderma gangrenosum with characteristic pathergy phenomenon. The diagnosis was established based on clinical appearance and histopathological findings. Also, diagnostic and therapeutic methods were much discussed.