Three Patterns of Cutaneous Involvement in Granulomatosis with Polyangiitis

Background Skin involvement in granulomatosis with polyangiitis (GPA) is common and can appear as an initial presentation of the disease or more commonly through its course. Case presentation We report a case of a 24-year-old male patient, previously diagnosed as having GPA, admitted with fever, hemoptysis, generalized hemorrhagic blisters associated with arthralgia, fatigue, myalgia, nasal crusting, and vertigo. Three weeks prior to admission, he developed erythematous papules on both elbows, and purpuric papules on both lower limbs. Histopathological examination revealed: interstitial granulomatous dermatitis (elbows) and foci of dermal hemorrhage, foci of interstitial histiocytes and zones of altered necrobiotic collagen (lower limbs) consistent with cutaneous lesions of GPA. Two weeks later, his rash progressed to widespread purpura associated with hemorrhagic blisters. Another biopsy revealed leukocytoclastic vasculitis with fibrinoid necrosis of the vessel walls associated with perivascular infiltrate of neutrophils, nuclear dust and extravasated erythrocytes without an associated granulomatous inflammation or necrobiosis. The constellation of the results of the three biopsies together with clinical correlation pointed to a flare of GPA. Conclusion Skin involvement in GPA is quite common, and it can manifest in different forms in the same patient. Our patient developed three different skin pathologies within a short period of time.