Use of muscle biopsies for diagnosis of systemic vasculitides

A Curious Case of Weakness: Antineutrophil Cytoplasmic Antibody-Associated Vasculitis Presenting With Muscle Weakness

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.

Muscle Biopsy-proven Drug-induced Microscopic Polyangiitis in a Patient with Tuberculosis

We herein report a case of muscle biopsy-proven microscopic polyangiitis (MPA) in a patient with tuberculosis. The patient had developed a persistent fever after the initiation of treatment for tuberculosis and was positive for myeloperoxidase-antineutrophil cytoplasmic antibody (ANCA). However, because conventional symptoms were lacking, determination of the biopsy site was difficult. Based on the findings of a biopsy of the biceps femoris, which confirmed small vessel vasculitis, the patient was diagnosed with MPA. The fever was alleviated by glucocorticoids. Tuberculosis and antituberculosis drugs can cause ANCA-associated vasculitis (AAV). A muscle biopsy is useful for the diagnosis of AAV.

Myeloperoxidase-positive ANCA-associated vasculitis presenting as myalgia, proximal weakness and a normal CK

We describe an unusual presentation of myeloperoxidase positive antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis managed by a multidisciplinary approach. A 75-year-old man gave a 3-week history of proximal lower limb weakness and exertional myalgia. His serum creatine kinase was normal and many of his non-specific symptoms suggested small vessel vasculitis. His investigations for common causes of muscle weakness were normal, and renal biopsy was normal despite haemoproteinuria. CT scan of the chest identified a pulmonary nodule of uncertain significance, not amenable to biopsy. MR scan of the thighs showed muscle oedema, and muscle biopsy confirmed typical features of vasculitis. Following high-dose corticosteroids his exertional myalgia quickly resolved and his normal mobility returned. Early immunosuppression is essential to improving clinical outcomes in ANCA-associated vasculitis, but diagnostic investigations often lack sensitivity.

[Differential diagnosis of a vasculitic syndrome of the lower limb]

Vasculitides can present with various clinical signs and symptoms. Besides disease-specific organ manifestations, the skin, peripheral nerves and musculature are frequently involved. The combination of elevated serological inflammatory markers, vasculitic skin lesions, active polyneuropathy and immobilizing myalgia of the lower limb musculature is highly suspicious for muscular polyarteritis nodosa (mPAN). Based on the case of a 63-year-old female patient with a vasculitic syndrome confined to the lower limb due to mPAN, important differential diagnoses of the these disease manifestations are discussed. Magnetic resonance imaging of the affected muscles and subsequent muscle biopsy (including skin and fascia) provide the relevant diagnostic data.

A Unique Case of Myositis

Anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) is a rare systemic small-vessel disease, with heterogeneous clinical manifestations. While arthralgia and myalgia are common in the disease course, frank myositis is exceedingly rare. Immune-mediated necrotizing myopathy (IMNM) is a subtype of idiopathic inflammatory myopathies (IIMs), characterized by severe myositis. We report herein a case of prominent diffuse myositis with shared features of AAV and IMNM.

The "Ant-farm"-like Appearance of Restricted Lower Limb Vasculitis on Fluorodeoxyglucose-positron Emission Tomography

Restricted lower limb vasculitis is a type of localized muscle vasculitis limited to the lower limbs. The usefulness of fluorodeoxyglucose-positron emission tomography (FDG-PET) for the diagnosis of this entity has not yet been reported. We herein report three patients with a fever and persistent lower limb pain. FDG-PET revealed linear and patchy FDG uptakes in their lower limbs. Combined with magnetic resonance imaging and histological findings, they were diagnosed with lower limb vasculitis. Linear and patchy FDG uptakes are considered to reflect the presence of muscle vasculitis. The characteristic "ant-farm"-like FDG-PET images can be a diagnostic clue for the currently overlooked vasculitis.

Inflammatory muscle involvement in systemic vasculitis: A systematic review

Vasculitis are severe systemic autoimmune diseases which may involve different organs and systems. Conversely, muscles do not represent an organ commonly involved by systemic vasculitis and myositis is not include among any classification or diagnostic criterion of vasculitis. In this regard, we aimed to review the literature in order to report all the available evidence concerning the inflammatory involvement of muscle in patients affected by systemic vasculitis. We collected a total of 108 papers, for a sum of 395 patients affected by muscle vasculitis. Most of them suffered from medium and small vessels vasculitis (mainly polyarteritis nodosa and ANCA-associated vasculitis) or from vasculitis secondary to rheumatoid arthritis. Conversely, muscle involvement in case of large vessel vasculitis occurred seldom, while only few papers reported such occurrence in Kawasaki or Behçet's disease. Histological findings may differ, but the most common ones displayed a necrotizing vasculitis of perimysium vessels, while granulomatous vasculitis was assessed only in case of ANCA-associated vasculitis patients. Creatine kinase were usually within normal range, seldom elevated, while imaging findings were generally undistinguishable from the ones found in idiopathic inflammatory myopathies: magnetic resonance imaging displays signal hyperintensity in T2 and STIR scans, while few data exist for positron emission tomography. The presentation of the disease may be fearsome and severe, sometimes life-threatening, but an overall good response to conventional immunosuppressants and/or glucocorticoids has been reported.

Muscle biopsy in anti-neutrophil cytoplasmic antibody-associated vasculitis: diagnostic yield depends on anti-neutrophil cytoplasmic antibody type, sex and neutrophil count

OBJECTIVES

This study aimed to examine the sensitivity of muscle biopsy (MB) in ANCA-associated vasculitis (AAV), identify factors predicting MB positivity and assess the prognostic value of a positive MB.

METHODS

We conducted a single-centre retrospective study of AAV with an MB performed at diagnosis. AAV classification [granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), eosinophilic granulomatosis with polyangiitis (EGPA)] followed the European Medicines Agency algorithm. A logistic regression model was used to identify the factors associated with MB positivity. Survival curves were generated using the Kaplan-Meier method.

RESULTS

Among 276 AAV patients (1995-2018), 101 had an MB. Seventy-eight patients were included: 33 with GPA, 25 with MPA and 20 with EGPA. MB samples were positive in 45 cases (58%): 17 GPA, 16 MPA and 12 EGPA. Univariate analysis focussed on GPA and MPA, revealed that the MB yield was higher in females [22/31 (71%) vs 11/27 (41%); P = 0.02] and in anti-MPO patients [25/37 (68%) vs 6/19 (32%) for anti-PR3; P = 0.01]. By multivariate analysis, three factors predicted MB positivity: anti-MPO ANCA [odds ratio (OR) 10.67 (CI 2.09, 81.68)], female sex [OR 5.3 (CI 1.16, 32.35)] and neutrophil count [OR 1.33 (CI 1.07, 1.8)]. MB positivity had no impact on relapse, death or end-stage renal disease-free survival.

CONCLUSIONS

MB is a safe and efficient diagnostic tool for AAV. Predictors of MB yield include ANCA type, sex and neutrophil count. MB cannot substitute for kidney biopsy when indicated, but should be considered in other cases.

Clinical characteristics of patients with myalgia as the initial manifestation of small and medium-sized vasculitis: a retrospective study

Myalgia is a common symptom in small and medium-sized systemic vasculitis, sometimes occurring as the initial or only clinical manifestation of vasculitis. This study investigated the clinical features and diagnostic process in patients presenting with myalgia as the initial symptom of anti-neutrophil cytoplasmic antibody-associated vasculitis (AAV) or polyarteritis nodosa (PAN). We included 93 patients diagnosed with AAV or PAN by retrospectively reviewing their clinical records at the initial diagnosis. Clinical findings and diagnostic methods were assessed in patients with myalgia. Of 93 patients, myalgia was observed in 21 (22.6%) patients, with diagnostic classifications of microscopic polyangiitis (MPA) in 12 (52.4%), granulomatosis with polyangiitis in 2 (9.5%), eosinophilic granulomatosis with polyangiitis in 2 (9.5%), and PAN in 5 (23.8%). Myalgia was present in the lower extremities of all patients; more than 80% of patients had pain in the calf muscle. In 10 patients with myalgia, including 7 with MPA and 3 with PAN, muscle biopsy was performed because myalgia was the main symptom and no other impaired organs were suitable for biopsy. Consequently, 8 patients had necrotizing vasculitis, leading to MPA or PAN diagnosis, although muscle pathology was not evaluated in patients without myalgia. Muscle magnetic resonance imaging was useful in determining the biopsy site. Myalgia, especially in the lower limbs, may be an initial clinical sign of vasculitis, particularly in MPA or PAN patients. Moreover, the histological evidence of muscular vasculitis can contribute to a definite diagnosis especially in patients presenting with myalgia as an early symptom of AAV or PAN.

Severe proximal muscle weakness with normal CK as a presenting feature of ANCA-associated vasculitis

Antineutrophil cytoplasmic antibodies associated vasculitis (AAV) presenting with muscle weakness is rarely reported. We report a case of myeloperoxidase positive vasculitis presenting with severe proximal muscle weakness with normal creatine kinase and no positron-emission tomography uptake. There was a significant delay in the diagnosis of AAV due to atypical presentation. We propose AAV be considered in the differential diagnosis of proximal muscle weakness after excluding the common causes.

Muscle weakness as a presenting symptom in ANCA-associated vasculitis

Muscle weakness is rarely a presenting symptom of anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV), although the disease frequently involves the lungs, skin, neurons, and kidneys. Here we describe a case of AAV presenting with muscle weakness in which only muscle biopsy could confirm the diagnosis. The literature review, including three similar cases, suggested that patients with ANCA-associated muscle vasculitis likely had myalgia, normal levels of creatine kinase, pulmonary fibrosis, rheumatoid factor, and muscle edema on MRI.

Churg strauss syndrome - a case report

A male aged 45-years presented with complaints of fever for 7days, cough, breathlessness for 4 days, tingling of hands, feet and weakness of both hands and feet for 4 days duration. He was a known asthmatic with history of recurrent sinusitis in the past. On examination he had bilateral polyphonic wheeze and evidence of distal asymmetric sensory neuropathy with motor weakness. And on investigation he had eosinophilia, pulmonary function test showed reversible airway obstruction,nerve conduction studies revealed mononeuritis multiplex, muscle biopsy suggestive of eosinophilia infiltration, nerve biopsy suggestive of vacuities, 2DECHO showed RWMA in inter ventricular septum, Coronary angiogram showed narrowing in distal LAD territory. In view of sinusitis, asthma, eosinophilia, tissue infiltration by eosinophils we made a diagnosis of Churg Strauss syndrome.