Management of Idiopathic Pyoderma Gangrenosum With Azathioprine As the Primary Adjunct in an Asian Man: A Case Report

Pyoderma gangrenosum (PG) is a very rare, non-infectious, progressive inflammatory condition falling under the umbrella of neutrophilic dermatoses. It is an ulcerative condition with a wide variety of cutaneous manifestations and multiple clinical variants (classic ulcerative, pustular, bullous, and superficial granulomatous). Additionally, owing to similar patterns of mucocutaneous ulceration, it has certain overlaps with other neutrophilic diseases frequently observed in clinical practice. Pyoderma gangrenosum may occur in association with systemic conditions such as inflammatory bowel disease, hematological malignancies, or as a part of an inherited inflammatory syndrome. However, in rare cases, it may have an idiopathic origin as well. With no specific standardized diagnostic and treatment protocols in place, the management of pyoderma gangrenosum is primarily guided by pre-existing literature or is tailored according to the individual’s disease pattern, type, and associations. Currently, the pathophysiology of pyoderma gangrenosum remains elusive at best. All the aforementioned reasons contribute significantly to PG being labeled as a "diagnostic dilemma" or more commonly as a "diagnosis of exclusion" with frequent incidences of delayed diagnosis or misdiagnosis resulting in catastrophic delays in management. A 35-year-old Asian male presented with bilateral painful, violaceous ulcers with undermined edges involving the shins for the past three months. Routine investigations carried out were indicative of an underlying infection owing to a raised leucocyte count. Discharge from the lesion, however, showed no evidence of microbial growth. The ulcer progressively increased in size, despite optimal wound care and empirical treatment. Skin biopsy demonstrated central necrosis and ulceration of the epidermis and dermis with neutrophilic infiltrates. Phenomenon of pathergy was demonstrated following the formation of a new ulcer at the site of intravenous cannulation during hospital admission. Additionally, aggravation of pre-existing ulcers following their debridement was also indicative of a positive pathergy test. Ultimately, the diagnosis of pyoderma gangrenosum was made upon the successful exclusion of all the other differential diagnoses. Presence of an associated systemic disease could not be appreciated, leading to it being labeled as a case of idiopathic pyoderma gangrenosum. Supportive treatment with non-adhesive, moist dressings was initiated along with topical tacrolimus (0.1%) application. Treatment modalities utilized were steroids and azathioprine in divided doses owing to contraindications to the traditional option of cyclosporine. The patient showed a rapid response to steroids and azathioprine. The ulcers healed with characteristic cribriform scarring within three months of initiation of treatment.