結節性多発動脈炎

Diseases presenting with muscle symptoms are diverse. We report two cases initially suspected of idiopathic inflammatory myopathies (IIMs) that were ultimately diagnosed as polyarteritis nodosa and sarcoidosis, respectively. Case 1 was a 30-year-old man with fever, limb muscle pain, and elevated inflammatory markers. Muscle MRI showed high signal intensity on fat-suppressed T2-weighted images, and biopsy revealed vasculitis with fibrinoid necrosis, leading to a diagnosis of polyarteritis nodosa. Case 2 was a 70-year-old man with proximal muscle pain and weakness and elevated muscle enzymes. MRI showed high signal intensity in the thigh muscles, and biopsy revealed noncaseating granulomas consistent with sarcoidosis. These cases highlight the diagnostic pitfalls of interpreting MRI findings and serum creatine kinase levels in isolation when evaluating suspected IIMs and underscore the critical role of histopathological evaluation, including muscle biopsy, in establishing an accurate diagnosis.

BACKGROUND Polyarteritis nodosa (PAN) and Takayasu arteritis (TA) are systemic medium- and large-vessel vasculitides associated with significant morbidity when diagnosis is delayed. Although described in the literature, reports directly demonstrating the impact of diagnostic timing on vascular outcomes remain limited. This report presents 2 rare and contrasting cases highlighting the importance of early recognition with timely vascular and immunosuppressive interventions, which can prevent irreversible ischemic complications, whereas delayed diagnosis can result in permanent structural damage, reinforcing the need for accurate differentiation between PAN and TA. CASE REPORT Case 1 was a young woman with refractory hypertension and significant vascular manifestations, in whom PAN was diagnosed through combined analysis of symptoms, laboratory tests, and angiographic findings. Early angioplasty and treatment with glucocorticoids and azathioprine resulted in a favorable response. Case 2 was a woman with TA who had extensive involvement of the aorta and its branches with irreversible sequelae, including aortic valve replacement. Diagnostic delay led to progression. Glucocorticoids and adalimumab achieved clinical stabilization without reversing established structural damage. CONCLUSIONS The presented cases reinforce the importance of early identification and appropriate differentiation of systemic vasculitides to prevent irreversible vascular lesions. This study compares a case of PAN diagnosed early, with vascular intervention preventing ischemic complications, and a case of TA diagnosed late, with permanent structural damage despite treatment. Early use of vascular imaging combined with prompt immunosuppressive therapy and multidisciplinary management contributes to a favorable prognosis, highlighting the need for greater clinical awareness and careful diagnostic strategies in rare vasculitides.

BACKGROUND: Central nervous system (CNS) involvement in polyarteritis nodosa (PAN) is uncommon and typically manifests as ischemic or hemorrhagic events. Presentation as sterile meningitis is rare and may lead to diagnostic delay. CASE PRESENTATION: A 31-year-old man presented with persistent headache, high - grade fever, and nodular erythema on both calves. Cerebrospinal fluid (CSF) analysis demonstrated lymphocyte-predominant pleocytosis with elevated protein levels, initially suggesting a viral meningitis-like presentation. Despite empirical antiviral therapy, his symptoms failed to improve. On hospital day 7, the development of testicular discomfort and the presence of cutaneous nodules prompted further evaluation. Histopathological examination of a skin biopsy revealed fibrinoid necrosis of small arteries with inflammatory cell infiltration, confirming the diagnosis of PAN. Initiation of glucocorticoid therapy resulted in rapid clinical improvement. LITERATURE SYNTHESIS: A focused review of previously reported cases indicates that PAN may rarely present with meningitis-like features characterized by sterile CSF pleocytosis and lack of response to antimicrobial therapy, with marked improvement following immunosuppressive treatment. CONCLUSION: Aseptic meningitis-like presentation may represent an underrecognized CNS phenotype of PAN. In patients with persistent meningitis-like symptoms, negative infectious workup, and concomitant systemic manifestations such as skin nodules or testicular pain, vasculitis should be considered early to avoid diagnostic delay and improve outcomes.