It can also be part of a syndromes such as PAPA syndrome.One hallmark of  pyoderma gangrenosum is pathergy, which is the appearance of new lesions at sites of trauma, including surgical wounds. Diagnosis
Diagnosis of PG is challenging owing to its variable presentation, clinical overlap with other conditions, association with several systemic diseases, and absence of defining histopathologic or laboratory findings. Misdiagnosis and delayed diagnosis are common. It has been shown that up to 39% of patients who initially received a diagnosis of PG have an alternative diagnosis. In light of this, validated diagnostic criteria have recently been developed for ulcerative pyoderma gangrenosum. Diagnostic criteria
In addition to a biopsy demonstrating a neutrophilic infiltrate, patients must have at least 4 minor criteria to meet diagnostic criteria. These criteria are based on histology, history, clinical examination and treatment. Histology: Exclusion of infection (including histologically indicated stains and tissue cultures)
Pathergy (ulcer occurring at sites of trauma, with ulcer extending past area of trauma)
Personal history of inflammatory bowel disease or inflammatory arthritis
History of papule, pustule, or vesicle that rapidly ulcerated
Clinical examination (or photographic evidence) of peripheral erythema, undermining border, and tenderness at site of ulceration
Multiple ulcerations (at least 1 occurring on an anterior lower leg)
Cribriform or “wrinkled paper” scars at sites of healed ulcers
Decrease in ulcer size within 1 month of initiating immunosuppressive medications

Treatment
First-line therapy for disseminated or localized instances of pyoderma gangrenosum is systemic treatment with corticosteroids and ciclosporin. Topical application of clobetasol, mupirocin, and gentamicin alternated with tacrolimus can be effective.
Prax may refer to:

Prax (malware), or Regin, a malware and hacking toolkit
Prax Group, operators of Lindsey Oil Refinery, North Killingholme, North Lincolnshire, England
Praso, Italy (German: Prax), a former comune in Trentino, Italy
Mike Prax (born 1956), American politician from Alaska
Valentine Prax (1897–1981), French expressionist and cubist painter