Pyoderma gangrenosum associated with granulomatosis with polyangiitis: a case report

Pyoderma gangrenosum is an ulcerative disorder belonging to the neutrophilic dermatoses group. The pathogenesis of pyoderma gangrenosum is not fully understood and its association with granulomatosis with polyangiitis has been scarcely reported. Herein, we report a case of pyoderma gangrenosum in a young patient treated for granulomatosis with polyangiitis.

A 26-year-old Tunisian man presented with a 2-month history of bilateral nasal obstruction and bloody nasal discharge. Nasal endoscopic assessment revealed the presence of mucosal hyperemia, crusting, and granulation. Nasal biopsy showed chronic inflammation with necrosis. Clinical, radiological, and histological findings supported the diagnosis of localized granulomatosis with polyangiitis. The patient underwent therapy with intravenous methylprednisolone and intravenous cyclophosphamide, and was subsequently lost to follow-up. Three years later, the patient was readmitted with chief complaints of bloody crusting rhinorrhea, anosmia, persistent nasal obstruction, and a 4-month history of a large ulcer in the right lower limb. A computed tomography scan revealed complete lysis of the nasal septum and nasal conchae, along with a perforation of the hard palate. On physical examination, he had a 20 cm lesion with necrosis and pus. The skin biopsy showed a dense inflammatory infiltrate formed by polymorphonuclear neutrophils with fragmented nuclei forming leukocytoclastic lesions associated with lymphocytes and histiocytes without signs of malignity. The diagnosis of pyoderma gangrenosum associated with granulomatosis with polyangiitis was made. He was also started on three methylprednisolone pulses relayed by oral corticosteroids and cyclophosphamide, with prompt recovery.

Skin involvement in granulomatosis with polyangiitis is common and is characterized by a wide spectrum of manifestations. However, the association between granulomatosis with polyangiitis and classic pyoderma gangrenosum is rare. The differential diagnosis between classic pyoderma gangrenosum and pyoderma gangrenosum-like ulceration is challenging. Only histopathological features can help practitioners differentiate the two conditions.