Disease manifestations of antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), a small vessel vasculitis with multisystemic effects, include respiratory, renal, nervous, gastrointestinal, and skin implications. Muscle weakness and inflammatory myopathy are rare manifestations of AAV. We report the case of a 77-year-old female with a medical history of hypothyroidism and osteoarthritis who presented with a two-month history of worsening muscle weakness (mainly proximal). She endorsed dysphagia, a 40-lb unintentional weight loss, and persistent sinusitis with middle ear effusions, requiring bilateral tympanostomy. The physical examination was notable for 2/5 muscle strength in her hip flexors and extensors, with 4/5 strength in other extremities. Lower extremity MRI showed diffuse intramuscular edema between fat planes and intramuscular septal regions. Erythrocyte sedimentation rate (70 mm/hr), C-reactive protein (141 mg/L), creatine kinase (690 U/L), and anti-myeloperoxidase (MPO) antibodies (>999 AU/mL) were elevated. A thigh biopsy revealed fibrinoid necrosis of small intramuscular arteries, confluent circumferential granulomatous vessel wall inflammation, and associated mild chronic inflammation, including occasional eosinophils and a few plasma cells. She was diagnosed with MPO-positive AAV. The patient was started on high-dose steroids (prednisone), with a taper on a disease-modifying agent, azathioprine, with significant improvement in symptoms over the next four months and complete resolution at 16-month follow-up. This patient\'s clinical presentation of predominant lower extremity weakness due to inflammatory myositis is an unusual manifestation of AAV. Clinicians should keep a broad differential diagnosis and consider the possibility of AAV, especially in cases of muscle weakness presenting as inflammatory myositis, in the absence of other clinical manifestations of systemic vasculitis or specific myositis serologies.

Antineutrophil cytoplasmic antibody-related vasculitis (AAV), is a group of diseases marked by systemic symptoms and severe small vessel inflammation. The three subtypes of AAV are eosinophilic GPA (EGPA), Microscopic Polyangiitis (MPA), and Granulomatosis with Polyangiitis (GPA). The organs that get involved in the disease process are the kidneys and the upper and lower respiratory tracts, with a spectrum of neurological manifestations. Here, we present a case report of a 68-year-old man who came with complaints of tingling and numbness over bilateral lower limbs for two months accompanied by difficulty in walking and bilateral foot drop without any respiratory complaints or involvement of sensory or autonomic system who was diagnosed with AAV (c-ANCA +) on further workup. A sural Nerve biopsy was done for confirmation which was suggestive of chronic, asymmetrical axonal neuropathy with perivascular inflammation, suggestive of vasculitic neuropathy. The patient had no other organ involvement. The patient was started on glucocorticoids and cyclophosphamide therapy for 6 cycles after which his symptoms and quality of life improved drastically.

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis is a systemic necrotizing vasculitis that affects small to medium-sized vessels. We describe two cases of patulous Eustachian tube (PET) in patients with otitis media with ANCA-associated vasculitis (OMAAV). The two cases presented in this paper had previously been diagnosed with Eustachian tube (ET) stenosis, and both presented with bilateral aural fullness, with one also experiencing postnasal drip and hearing loss. Both patients experienced positive myeloperoxidase (MPO)-ANCA and negative proteinase 3 (PR3)-ANCA, and treatment for ANCA-associated vasculitis (AAV) resulted in a diagnosis of PET. The patients were treated with transnasal self-installation of physiological saline into the pharyngeal orifice of the ET. This paper highlights the importance of considering PET in the differential diagnosis of OMAAV patients presenting with aural fullness.

Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) refers to a group of disorders characterized by inflammation and destruction of small- and medium-sized blood vessels. It can be classified into various clinical disease phenotypes: granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), eosinophilic granulomatosis with polyangiitis (EGPA), and renal-limited AAV or serologic subtypes, which are myeloperoxidase (MPO)-AAV and proteinase 3 (PR3)-AAV. Renal involvement is a common manifestation in these types of vasculitis. MPO-AAV usually involves the glomeruli causing membranous changes and presents with glomerulonephritis. However, MPO-AAV renal type without glomeruli involvement is much rarer, and very few case reports of this condition have been reported in the literature. Once the diagnosis is confirmed by renal biopsy, the treatment of AAV involves high-dose steroids and cyclophosphamide to induce remission. Rituximab, a chimeric monoclonal antibody that targets against the pan-B-cell marker CD20, was the first monoclonal antibody to be approved for the treatment of vasculitis. It is now considered first-line therapy for ANCA vasculitis with kidney involvement thanks to the higher remission rates associated with it. We report a unique and rare case of acute kidney injury due to MPO-AAV without glomeruli involvement, which was successfully treated with rituximab over a period of 12 months and led to the remission of the disease in the kidneys.

Eosinophilic granulomatosis with polyangiitis (EGPA) is a systemic necrotizing vasculitis accompanied by granulomas and eosinophilic inflammation, exhibiting marked peripheral blood eosinophiliaandasthma. Neuropathy is a difficult-to-treat common manifestation that frequently remains after achieving clinical remission with current therapy in a subpopulation of patients with EGPA with or without life-threatening organ involvement. Refractory neuropathy regularly reduces the quality of life and requires glucocorticoids (GCs) and/or immunosuppressants for a long time. Long-term immunosuppressive therapy is a factor associated with a high risk of adverse effects. Mepolizumab, at three times the dose for severe asthma, provides benefits to induce the remission of relapsing or refractory EGPA and to reduce the doses of GC. Here, we present a case of EGPA successfully treated with mepolizumab at the reference dose for severe asthma. In this case, mepolizumab resolved peripheral neuropathy resistant to corticosteroids, immunosuppressants, and intravenous immunoglobulin and contributed to the improvement of comorbid chronic pulmonary aspergillosis during GC dose reduction.

Granulomatosis with polyangiitis (GPA), formerly Wegener\'s granulomatosis, is a small- and medium-vessel vasculitis with characteristic cutaneous morphologic presentation and systemic involvement. Most patients have palpable purpura at some point in their disease course, but this is not always the presenting manifestation. This autoimmune disorder can affect a range of organs, with the upper and lower respiratory tract, kidneys, and nervous system being commonly implicated, while gastrointestinal and cardiac involvement is less frequent. This is a 44-year-old female presenting to the emergency department (ED) with polyarthralgia and palpable purpura. Palpable purpura was distributed on the oral palate, elbow, and lower back, and a punch biopsy revealed leukocytoclastic vasculitis (LCV). While this was an atypical distribution for leukocytoclastic vasculitis, the skin biopsy provided the necessary evidence to diagnose GPA. This case characterizes non-specific and atypical signs and symptoms of GPA that all providers should be aware of in order to diagnose the condition early in its disease course.

Peripheral neuropathy is a common manifestation of Eosinophilic Granulomatosis with Polyangiitis (EGPA), a rare autoimmune disorder caused by eosinophilic infiltration of multiple organs including the nervous system. Recent research has shown an association between myelin oligodendrocyte glycoprotein (MOG) antibodies and various neurologic conditions. We present a unique case of EGPA with positive MOG antibodies in the cerebrospinal fluid (CSF) in a patient presenting with peripheral neuropathy. We also highlight a few diagnostic dilemmas with EGPA and the importance of early diagnosis and appropriate treatment. Clinical, laboratory, radiological, and electrophysiologic findings are discussed.

We describe a rare case of concurrent eosinophilic granulomatosis with polyangiitis and mixed connective tissue disease in a 27-year-old man who presented with pulmonary, renal, cardiac, and skin manifestations. We confirmed the diagnosis based on clinical, histopathological, and serological criteria. We treated the patient with corticosteroids, methotrexate, cyclophosphamide, and hydroxychloroquine, achieving early remission. The coexistence of both conditions in the same patient is extremely rare and has only been reported in a few cases worldwide. We also review the literature on these two rare autoimmune diseases\' coexistence, pathogenesis, diagnosis, and management. Our case emphasizes recognizing overlapping autoimmune conditions in patients with complex clinical features and employing a comprehensive diagnostic approach and tailored treatment strategies. Further research is needed to understand these patients\' epidemiology, prognosis, and optimal therapy. Early diagnosis and aggressive immunosuppression are crucial for achieving remission and preventing organ damage. We also identified the knowledge gaps and research needs in this field.

Granulomatosis with polyangiitis (GPA) is an antineutrophil cytoplasmic antibody (ANCA)-associated necrotizing vasculitis of small to medium-sized blood vessels. The typical presentation is the classic triad of upper airway, pulmonary, and renal involvement. However, it can rarely present with the involvement of a single organ system known as limited granulomatosis with polyangiitis. We present a case of a 53-year-old male with chronic rhinosinusitis as the only manifestation of limited GPA. The diagnosis was established incidentally based on biopsy findings from the paranasal sinuses obtained during functional endoscopic sinus surgery. Subsequent testing revealed a positive cytoplasmic antineutrophilic antibody. No evidence of systemic involvement was noted. Prednisone and azathioprine were initiated leading to significant improvement. Although upper respiratory tract involvement is common in GPA, it is rare for the condition to be limited to this organ system. Our case of limited GPA is distinct in that it represents a rare presentation of this already rare disease.

Anti-neutrophil cytoplasmic antibody (ANCA) associated vasculitis is a systemic autoimmune disease that typically presents as a multi-organ manifesting disease of unclear etiology that can predispose to rapidly progressive glomerulonephritis (RPGN). If left untreated, ANCA-associated vasculitis can be fatal, and RPGN can progress to irreversible renal failure. Environmental and genetic factors have been implicated in the pathogenesis of this vasculitis. Coronavirus disease (COVID-19) has been noted to have various physiologic impacts on the body, with literature indicating possible autoimmune effects. We present a rare case of ANCA-associated vasculitis in an elderly male with no known autoimmune history after a recent illness with COVID-19. The patient had been seen as an outpatient with progressively declining renal function until he presented to the hospital with acute renal failure and pericarditis. Workup revealed elevated anti-myeloperoxidase antibody (MPO-AB) and perinuclear ANCA (p-ANCA) antibodies with a biopsy confirming focal cresenteric glomerulonephritis, and the patient was initiated on steroid therapy with notable improvement and a return to baseline kidney function.