Extracutaneous involvement of pyoderma gangrenosum.

Pyoderma Gangrenosum (PG) is an inflammatory neutrophilic dermatosis (ND) associated with underlying chronic inflammation and/or malignancy. Diagnosis remains to be challenging as a gold standard diagnostic test is lacking. Initial manifestations may include papules, vesicles, or pustules that subsequently develop into ulceration with features of undermining and violaceous borders. Timely recognition of pyoderma gangrenosum is impeded by clinical findings shared with other etiologies, such as granulomatosis with polyangiitis, polyarteritis nodosa, and antiphospholipid syndrome. As with any other ND, extracutaneous involvement may also occur preceding, during, or following the appearance of skin lesions. Sterile neutrophilic infiltrates have been found to affect internal organs supporting the concept of PG being a systemic disease, with lung being the most common extracutaneous manifestation followed by ocular and visceral compromise. Therefore, in this review, we describe the current knowledge of extracutaneous involvement of PG and its respective clinical manifestations to aid dermatologists in diagnosis, management, and determining prognosis.