An 18 year old boy presents with digital gangrene of the third and fouh fingers over the last 2 weeks. On examination the blood pressure is 170/110 mm of Hg and all peripheral pulses were palpable. Blood and urine examinations were unremarkable. ANA, Anti-dsDNA and ANCA were negative. Which of the following represents the most likely diagnosis?

Patient is showing features of PAN. It is a multisystem, necrotizing vasculitis of small and medium-sized muscular aeries mainly involving the renal and visceral aeries. It does not involve pulmonary aeries, although bronchial vessels may be involved. Clinical features: Patients often present with nonspecific symptoms such as fever, weight loss, and malaise and weakness. Hypeensions, ahritis, peripheral neuropathy, cutaneous infarcts, Raynaud's phenomenon are complaints related to specific organ system involvement. Investigations: There are no diagnostic serologic tests for PAN. Anemia of chronic disease, neutrophilic leukocytosis, and an elevated ESR is almost always present. Hypergammaglobulinemia may be present, and all patients should be screened for hepatitis B. Antibodies against myeloperoxidase or proteinase-3 (ANCA) are rarely found in patients with PAN. Ref: Harrison's Internal Medicine, 18th Edition, Chapter 326, Pages 2726-2727, 2789, 2794, 2796