The illness initially presents with a prodromal phase characterized by fever, myalgia, arthralgia, and weight loss. The manifestations that follow are reflective of which systems are affected. The kidneys are involved in as many as 90% of all patients. Hematuria is one of the common signs. Kidney disease can rapidly evolve into renal failure. Individuals with gastrointestinal (GI) disease exhibit nausea, emesis, diarrhea, abdominal pain, and bloody stools.

Additionally, vasculitis of the lungs may result in alveolar hemorrhage and pulmonary fibrosis. The former is typified by a sudden onset of dyspnea and is possibly accompanied by hemoptysis. Other symptoms of the respiratory disease are rhinitis, sinusitis, and epistaxis. Patients with neurologic sequelae experience mononeuritis multiplex, which affects peripheral or cranial nerves. Furthermore, severe complications may include stroke or seizures.

Approximately one-third of individuals have vasculitis of the skin, which results in purpura rash, and possibly splinter hemorrhages. Finally, episcleritis arises in ocular vasculitis.

• Fever

  The titer of MPO-ANCA decreased with the treatment, but fever recurred with prednisolone taper. [ncbi.nlm.nih.gov]

  With intravenous antibiotics his fever, sweating and elevated inflammatory markers improved and after two weeks antibiotics were stopped. [bjcardio.co.uk]

• Weight Loss

  In addition, generalized symptoms such as fever and weight loss are very common. CASE REPORT - In January 2013 a 56-year old woman presented with weight loss, lower leg numbness, walking difficulty and petechiae on the lower legs. [hungary.pure.elsevier.com]

  She was admitted because of fever, weight loss, and paresthesia of the plantae and fingers. Chest computed tomography revealed bilateral multiple nodules with calcification in the lung. [ncbi.nlm.nih.gov]

  In addition, generalized symptoms such as fever and weight loss are very common. The FIVE most common clinical manifestations of MPA are: Kidney inflammation (~ 80% of patients). Weight loss (> 70%). Skin lesions (> 60%). Nerve damage (60%). [hopkinsvasculitis.org]

• Anemia

  All of the patients presented with normocytic normochromic anemia. [ncbi.nlm.nih.gov]

  All of the 9 patients presented with normocytic normochromic anemia ( Table 2 ): 2 patients had mild anemia, with hemoglobin (Hb) ≥ 90 g/L; 3 patients had moderate anemia, with Hb 60–90 g/L; and 4 patients had severe anemia, with Hb < 60 g/L, who exhibited [journals.plos.org]

• Rapidly Progressive Glomerulonephritis

  Renal involvement, which can be the only manifestation, is clinically apparent as rapidly progressive glomerulonephritis and histopathologically as pauci-immune necrotizing and crescentic glomerulonephritis. [ncbi.nlm.nih.gov]

• Fatigue

  She was admitted to our hospital with symptoms of general fatigue, fever, and edema of the lower limbs. [ncbi.nlm.nih.gov]

  She reported fatigue and mild hearing impairment. Headaches and jaw claudication were absent and there were no other symptoms to suggest giant cell arteritis. [doi.org]

  […] affects small vessels without granulomata. 3 In the UK the incidence is less than two in 100,000, with an equal sex distribution and an average age of onset in the fifth decade. 2 Clinical features include constitutional symptoms such as fever, anorexia, fatigue [bjcardio.co.uk]

  Usually includes combinations of two or more of the following: Nonspecific constitutional symptoms, including fatigue, myalgias, weight loss, and fevers. Migratory arthralgias or arthritis, either pauciarticular or polyarticular. [accessmedicine.mhmedical.com]

• Hemoptysis

  Diffuse alveolar hemorrhage was the most frequent presentation of lung involvement in children with MPA, and tachypnea, cough, hemoptysis and anemia were the common clinical symptoms. [ncbi.nlm.nih.gov]

  Hemoptysis occurred during the course of illness in 40%. Pulmonary evaluation included bronchoscopy in 60% and surgical lung biopsy in 12%, usually related to pulmonary hemorrhage. [acrabstracts.org]

  Seven patients manifested with cough or hemoptysis as the initial symptom, 4 (patients 3, 4, 7 and 8) of whom had been diagnosed with idiopathic pulmonary hemosiderosis (IPH). [journals.plos.org]

• Rhinitis

  He reports also having allergic rhinitis in the past few weeks, which was strange given that he normally has allergic rhinitis in the spring. [medbullets.com]

  Mild symptoms of rhinitis, epistaxis, and sinusitis may occur; however, if the upper respiratory tract is severely affected, the cause is more likely to be granulomatosis with polyangiitis. [merckmanuals.com]

  ImmunoCAP™ Specific IgE Tests Worldwide gold standard in in vitro allergy diagnostics2 designed to aid providers in the diagnosis of allergic diseases including allergic asthma, allergic rhinitis, and food allergies, with more than 550 whole allergens [thermofisher.com]

• Abdominal Pain

  Clinicians should consider the possibility of hemocholecyst in patients with MPA complaining of abdominal pain. [ncbi.nlm.nih.gov]

  Gastrointestinal (GI): GI symptoms include abdominal pain, nausea, vomiting, diarrhea, and bloody stools. [merckmanuals.com]

• Vomiting

  Gastro-intestinal involvement can present with abdominal pain, nausea, or vomiting, and can be life-threatening in case of peritonitis, ischemia or perforation. [orpha.net]

  The occurrence of vomiting, food refusal and impaired consciousness in non-survivors were more than survivors (P<0.005). [indianpediatrics.net]

  Digestive tract: Abdominal pain, nausea, vomiting, and diarrhea may occur. Stools may contain blood. Nerves: People may have tingling, numbness, or weakness in a limb. Other organs, such as the heart, are affected less often. [msdmanuals.com]

• Nausea

  Gastro-intestinal involvement can present with abdominal pain, nausea, or vomiting, and can be life-threatening in case of peritonitis, ischemia or perforation. [orpha.net]

  Individuals with gastrointestinal (GI) disease exhibit nausea, emesis, diarrhea, abdominal pain, and bloody stools. Additionally, vasculitis of the lungs may result in alveolar hemorrhage and pulmonary fibrosis. [symptoma.com]

  Digestive tract: Abdominal pain, nausea, vomiting, and diarrhea may occur. Stools may contain blood. Nerves: People may have tingling, numbness, or weakness in a limb. Other organs, such as the heart, are affected less often. [msdmanuals.com]

• Diarrhea

  Individuals with gastrointestinal (GI) disease exhibit nausea, emesis, diarrhea, abdominal pain, and bloody stools. Additionally, vasculitis of the lungs may result in alveolar hemorrhage and pulmonary fibrosis. [symptoma.com]

  Digestive tract: Abdominal pain, nausea, vomiting, and diarrhea may occur. Stools may contain blood. Nerves: People may have tingling, numbness, or weakness in a limb. Other organs, such as the heart, are affected less often. [msdmanuals.com]

• Loss of Appetite

  The early clinical manifestations are indicative of systemic inflammation: fever, arthralgias, myalgias, fatigue, and/or loss of appetite. [orpha.net]

  Patients who have MPA may feel generally ill and fatigued, have fever, or have loss of appetite and weight. They usually also have symptoms related to areas of involvement such as rashes, muscle and/or joint pain. [my.clevelandclinic.org]

  Signs and symptoms[edit] Clinical features may include constitutional symptoms like fever, loss of appetite, weight loss, fatigue, and kidney failure.[1] A majority of patients may have blood in the urine and protein in the urine. [en.wikipedia.org]

• Oral Ulcers

  ulcers, epistaxis, sinusitis Renal – rapidly progressing glomerulonephritis Cardiovascular – pericarditis, endocarditis Neurological – mononeuritis multiplex, sensorimotor polyneuropathy Dermatological – palpable purpura, papules, ulcers Ophthalmological [arupconsult.com]

  […] friable, red gingivae "strawberry gums" oral ulcers upper respiratory tract involvement nasal ulcers perforation of the nasal septum chronic sinusitis, otitis media, or mastoiditis lung involvement hemoptysis cough dyspnea renal involvement hematuria [medbullets.com]

  Nasal or oral inflammation: painful or painless oral ulcers or purulent or bloody nasal discharge Lungs: abnormal chest X-ray with: nodules, infiltrates or cavities Kidneys: urinary sediment with: microscopic hematuria or red cell casts Biopsy: granulomatous [en.wikipedia.org]

  […] inflammation (oral ulcers or bloody nasal drainage) </li></ul><ul><li>Abnormal chest radiograph (nodules, fixed infiltrates, cavities) </li></ul><ul><li>Urinary sediment (>5 RBC/hpf or RBC casts) </li></ul><ul><li>Granulomatous inflammation on biopsy [slideshare.net]

• Arthralgia

  Abstract A 68-year-old man, who had worked for processing quartz-containing stones for more than 50 years, complained of low-grade fever and arthralgia. Mediastinal lymph nodes were markedly swollen on chest computed tomography. [ncbi.nlm.nih.gov]

  The early clinical manifestations are indicative of systemic inflammation: fever, arthralgias, myalgias, fatigue, and/or loss of appetite. [orpha.net]

  The cutaneous involvement is present at an early stage of microscopic polyangiitis with other non-specific symptoms, such as arthralgias and myalgias. [medicaljournals.se]

• Myalgia

  We report a case of a 76-year-old woman, presenting with a persistent dry cough, subfebrility, arthralgia and myalgia, weight loss and a breast lesion. [ncbi.nlm.nih.gov]

  The early clinical manifestations are indicative of systemic inflammation: fever, arthralgias, myalgias, fatigue, and/or loss of appetite. [orpha.net]

  We describe the case of a 76-year-old man with microscopic polyangiitis (MPA) presenting with myalgia, abnormal muscle MRI findings and pulmonary fibrosis. [tandfonline.com]

  The cutaneous involvement is present at an early stage of microscopic polyangiitis with other non-specific symptoms, such as arthralgias and myalgias. [medicaljournals.se]

  History Constitutional manifestations of microscopic polyangiitis (MPA) include the following: Fever (55%) Malaise, fatigue, flulike syndrome Myalgia (48%) Weight loss (72%) Other manifestations of MPA include the following: Skin - Rash (50%) Pulmonary [emedicine.medscape.com]

• Purpura

  In two patients, a Henoch-Shönlein purpura-like eruption developed with necrotizing vasculitis localized in the upper dermis. [ncbi.nlm.nih.gov]

  Skin findings are as follows: Leukocytoclastic angiitis and its palpable purpura - Leukocytoclastic purpura could be a manifestation of the systemic vasculitides or could be a stand-alone skin disorder (see image below.) Leukocytoclastic angiitis. [emedicine.medscape.com]

  Common sites of involvement are kidneys: necrotizing glomerulonephritis (present in ~90% of cases 1) lungs: pulmonary capillaritis skin: purpura gastrointestinal tract It is histologically very similar to polyarteritis nodosa except for involvement of [radiopaedia.org]

• Ulcer

  Retrograde double-balloon endoscopy after treatment showed ulcer scars and no ulcer. The cause of gastrointestinal involvement in microscopic polyangiitis is ischemia due to vasculitis. [ncbi.nlm.nih.gov]

  Gastroscopy and a colonoscopy were performed; denudation with capillary bleeding upon contact plus superficial and deep ulcers were observed, thus signs of vasculitis and inflammatory bowel disease were ruled out. [revistanefrologia.com]

  [archaic: Churg–Strauss syndrome ] eosinophil-rich, necrotizing granulomatous inflammation necrotizing vasculitis predominantly affecting small to medium vessels involvement of respiratory tract HISTORY rhinorrhea, bloody nasal discharge, oral/nasal ulcers [lifeinthefastlane.com]

  […] friable, red gingivae "strawberry gums" oral ulcers upper respiratory tract involvement nasal ulcers perforation of the nasal septum chronic sinusitis, otitis media, or mastoiditis lung involvement hemoptysis cough dyspnea renal involvement hematuria [medbullets.com]

  epistaxis, sinusitis Renal – rapidly progressing glomerulonephritis Cardiovascular – pericarditis, endocarditis Neurological – mononeuritis multiplex, sensorimotor polyneuropathy Dermatological – palpable purpura, papules, ulcers Ophthalmological – [arupconsult.com]

• Skin Rash

  He initially presented with prolonged fever, skin rash, and rapidly progressive glomerulonephritis. P-ANCA and anti-myeloperoxidase (MPO) antibodies were positive, but the c-ANCA and anti-proteinase-3 antibodies were negative. [ncbi.nlm.nih.gov]

  A 10-year-old girl visited our clinic with clinical manifestations suggestive Henoch-Schönlein purpura nephritis such as purpuric skin rash, abdominal pain, arthralgia on both knees, massive proteinuria and microscopic hematuria. [dbpia.co.kr]

  The most common symptoms of MPA include kidney inflammation, weight loss, skin lesions, nerve damage, and fevers.[2] Other symptoms depending on the area(s) of the body affected may include:[3] Skin-Rash Lungs-cough, breathing problems, spitting up blood [rarediseases.info.nih.gov]

• Skin Lesion

  Skin lesions Skin lesions in MPA, as in other forms of vasculitis that involve the skin, can erupt on various areas of the body. [hopkinsvasculitis.org]

  The patient was treated with prednisolone and mizoribine, resulting in an improvement in the skin lesions except for those on the knee. [ncbi.nlm.nih.gov]

• Eruptions

  This retrospective study analyzed clinical manifestations in patients of MPA with skin eruptions. [ncbi.nlm.nih.gov]

  "Skin eruptions associated with microscopic polyangiitis". Eur J Dermatol. 14 (4): 255–8. PMID 15319159. ^ Jayne D (January 2008). "Challenges in the management of microscopic polyangiitis: past, present and future". [en.wikipedia.org]

• Epistaxis

  […] crescentic glomerulonephritis on renal biopsy Differentiated from granulomatosis with polyangiitis (GPA) by absence of granulomatous inflammation Clinical Presentation Constitutional – weight loss, fever, myalgias Otorhinolaryngological – oral ulcers, epistaxis [arupconsult.com]

  She also complained of sinus congestion with occasional epistaxis. On exam, her nasal mucosa was significantly inflamed. [omicsonline.org]

  Pulmonary hemorrhage Lung infiltrates Gastrointestinal (50%) Abdominal pain Severe form with bowel perforation Hepatomegaly Neurologic (30%) Peripheral neuropathy less frequent than PAN Central nervous system Ear, nose, throat (30-35%) Mouth ulcers Epistaxis [basicmedicalkey.com]

  Mild symptoms of rhinitis, epistaxis, and sinusitis may occur; however, if the upper respiratory tract is severely affected, the cause is more likely to be granulomatosis with polyangiitis. [merckmanuals.com]

• Hematuria

  The majority of these patients exhibited hematuria, proteinuria and renal insufficiency. The efficacy of steroid plus CTX or leflunomide was evident in these patients. [ncbi.nlm.nih.gov]

  Hematuria and proteinuria are the primary manifestations of MPA [ 2, 15 ]. In the present study, most of the patients had renal lesions, with manifestations of hematuria and proteinuria. Mild-to-moderate proteinuria was frequently noted. [journals.plos.org]

  Studies urine studies hematuria red cell casts histology necrotizing vasculitis no granulomas laboratory studies + MPO-ANCA/p-ANCA (anti-myeloperoxidase) Treatment cyclophosphamide corticosteroids Please rate topic. [medbullets.com]

• Kidney Failure

  CONCLUSIONS: Geographical differences in the incidence of RRT for kidney failure due to granulomatosis with polyangiitis and microscopic polyangiitis copied their distribution in the general population. [ncbi.nlm.nih.gov]

  […] neuropathy, abdominal pain [2] The kidneys are affected in up to 80% of cases with signs of blood and protein in the urine and the injury can lead to either rapidly or slowly progressive kidney failure. [en.wikipedia.org]

  Almost all people with microscopic polyangiitis have kidney problems that can lead to raised blood pressure and kidney failure. People may find that they're tired because of anaemia. [versusarthritis.org]

• Renal Insufficiency

  The majority of these patients exhibited hematuria, proteinuria and renal insufficiency. The efficacy of steroid plus CTX or leflunomide was evident in these patients. [ncbi.nlm.nih.gov]

  In view of the patient's hepatic and renal insufficiency, antituberculosis treatment began with ethambutol, levofloxacin, and streptomycin. [archbronconeumol.org]

  The majority of these patients exhibit renal involvement, such as hematuria, proteinuria and renal insufficiency. [journals.plos.org]

• Seizure

  We hereby present a 14-year-old girl with arthralgia, seizure, leukocytoclastic vasculitis, interstitial lung disease secondary to recurrent pulmonary hemorrhage, pauci-immune glomerulonephritis and high titers of MPO-ANCA, hence diagnostic of microscopic [ncbi.nlm.nih.gov]

  […] http://www.orpha.net/ORDO/Orphanet_26 Methylmalonic acidemia with homocystinuria is an inborn error of vitamin B12 (cobalamin) metabolism characterized by megaloblastic anemia, lethargy, failure to thrive, developmental delay, intellectual deficit and seizures [ebi.ac.uk]

  Babies may also have weak muscle tone (hypotonia) and seizures. Most babies and children with this condition have an unusually small head size (microcephaly), intellectual disability and developmental delay. [rarediseases.info.nih.gov]

• Stroke

  For stroke patients with acute nephritis, the possibility of ANCA vasculitis should be considered. Early diagnosis may improve the prognosis. [ncbi.nlm.nih.gov]

  Patients with renal biopsy-proven A… Microscopic polyangiitis: an incidental finding in a patient with stroke. [unboundmedicine.com]

  Furthermore, severe complications may include stroke or seizures. Approximately one-third of individuals have vasculitis of the skin, which results in purpura rash, and possibly splinter hemorrhages. [symptoma.com]

  Long-term consequences of the disorder include neurological damage due to metabolic stroke affecting the brain stem, and end stage renal failure. [orpha.net]

• Dizziness

  If progesterone does make you dizzy or drowsy, take your daily dose at bedtime. you should know that progesterone may cause dizziness, lightheadedness, and fainting when you get up too quickly from a lying position. [medlineplus.gov]

  It can cause: extreme tiredness a high temperature (fever) weight loss muscle and joint pain dizziness shortness of breath painful, numb or cold limbs Treatment is usually with steroid medication. [nhs.uk]

  Others, such as iron-deficiency anemia, may result from heavy menstrual periods, ulcers, colon polyps and even an iron-poor diet, making you dizzy, cold, weak and irritable. [sharecare.com]

  It manifests as a sudden otalgia with hearing loss accompanied by dizziness and facial nerve palsy. Early diagnosis and treatment with immunosuppressive agents are important to prevent the irreversible progression of sensorineural hearing loss. [kjorl.org]

  Infusion-Related Reactions In the majority of patients with NHL, infusion-related reactions consisting of fever, chills/rigors, nausea, pruritus, angioedema, hypotension, headache, bronchospasm, urticaria, rash, vomiting, myalgia, dizziness, or hypertension [dailymed.nlm.nih.gov]

Individuals suspected to have vasculitis should be immediately evaluated with a detailed personal and family history, a physical exam, and comprehensive testing.

Laboratory tests

There are various potential findings in patients with MPA. For example, 80% are positive for ANCA, 60% for perinuclear ANCA (PANCA), and 40% for cytoplasmic ANCA (CANCA). Also, C3 and C4 complement studies are normal. Additional studies reveal leukocytosis and normocytic anemia on CBC and elevated ESR. Kidney function tests demonstrate increased blood urea nitrogen (BUN) and serum creatinine levels in 70% of patients, proteinuria in 80%, hematuria in almost 70%, and leukocyturia in 40%. Other results include the presence of erythrocyte casts and abnormal urine sediment. Note that blood cultures should be obtained to investigate bacterial endocarditis.

Imaging

The selection of imaging modalities is based on the present symptoms and complications. For example, patients with respiratory involvement should have a chest radiograph. This study typically displays bilateral nodular and patchy opacities, cavitary lesions, and parenchymal infiltrates. Furthermore, computed tomography (CT) and gastrointestinal endoscopy should be obtained for abdominal manifestations such as bleeding. Electromyography (EMG) is indicated in neuropathy while electrocardiography (ECG) is warranted for the evaluation of cardiac disease.

Other

Biopsies are performed for involved sites such as the skin, lungs, kidneys. and sural nerve. A muscle biopsy may be considered as well whether or not there is myalgia or other evidence of muscle involvement [10].

• Creatinine Increased

  Abstract A 76-year-old man developed fever and appetite loss, and then was referred to our hospital because of rapidly progressive renal insufficiency; his serum creatinine increased from 1.2 to 5.9 mg/dl within 1 month. [ncbi.nlm.nih.gov]

The treatment of MPA is centered on remission induction and maintenance.

Remission induction

Since glomerulonephritis is a common manifestation in patients with MPA, historically the regimen consisted of cyclophosphamide and glucocorticoids for both induction and maintenance [11]. However, cyclophosphamide is associated with serious adverse effects such as malignancy, hemorrhagic cystitis, and infertility [12]. Therefore, researchers sought to minimize the use of this toxic medication.

Currently, there are numerous approaches for the initiation of therapy. One method is to avoid cytotoxic drugs if possible. Hence, patients with mild to moderate renal disease may be spared the use of cyclophosphamide and require only glucocorticoids and mycophenolate mofetil [13]. Additional options include methotrexate [14] and leflunomide [15].

Another drug that represents an alternative to cyclophosphamide is rituximab. One trial compared the two medications [16] and observed that the six-month remission rate for rituximab was 63.6% in comparison to 53.1% with cyclophosphamide. Also, patients who continued taking low-dose glucocorticoids in conjunction with the respective medications had better remission rates. Also, rituximab offers a promising treatment for those with relapsing disease.

Remission maintenance

One trial investigated cyclophosphamide versus azathioprine for the management of the remission maintenance phase [17]. Prior to the treatment with one of these two agents, all patients received cyclophosphamide and prednisolone for remission induction. The relapse rate was similar in both groups, which was 15% in the cyclophosphamide patients and 10% in the azathioprine. The study notably reports that induction with cyclophosphamide and maintenance with azathioprine is as effective as prolonged therapy with cyclophosphamide.

Another trial evaluated the outcomes of maintenance therapy with methotrexate versus azathioprine after induction with cyclophosphamide [18]. The relapse rate was similar: 33% in the methotrexate group versus 36% in the azathioprine group.

Other

Additional therapies may be beneficial for patients with MPA. For example, plasma exchange has been compared with methylprednisolone as adjunctive agents. The study discovered that plasma exchange decreased the development of end-stage renal disease at the 12-month mark [19] although both groups had equal mortality rates.

Factors such as older age, the severity at onset, number of relapses, and the length of glucocorticoid therapy were correlated to long-term organ damage [8]. Also, according to one investigation, pulmonary involvement was associated with a greater risk for multisystem diseases affecting the heart and kidney [9].

Fortunately, treatment accounts for an improvement in 90% of affected individuals. Moreover, 75% of patients enter remission although 30% experience a recurrence in a year or two.

The survival rate at five years is about 75%. However, two of the leading causes of morbidity and death are necrotizing glomerulitis and hemorrhagic pulmonary capillaritis. Note that MPA has worse outcomes than some of the other vasculitis diseases.

While the exact etiology is unknown, the cause is likely multifactorial in origin consisting of genetic and environmental interplay. Patients often have a positive family history of other autoimmune diseases.

MPA has been associated with the use of drugs such as propylthiouracil, penicillamine, and hydralazine. Additionally, silica exposure is another environmental factor related to the etiology of the disease.

The incidence of this disease is estimated to be 1 in a population of 100,000. With regards to patient demographics, the average age of onset is 50 years. Also, there is a slight predilection for males [2] [3] [4].

While the pathophysiology is not well-elucidated, there is a theory that ANCA may be implicated in the development of MPA. Specifically, researchers speculate that primed neutrophils expressing myeloperoxidase (MPO) adhere to the endothelium of blood vessels and/or glomeruli and subsequently become activated by interacting with MPO-ANCA [5]. Furthermore, animal studies have reported that MPO-ANCA plays a role in glomerulonephritis and pulmonary capillaritis [6] [7].

It is important to note, however, that not all patients with MPA are ANCA positive. This suggests that there are other mechanisms that contribute to the pathogenesis of MPA. Very importantly, it is likely that this disease develops in genetically predisposed individuals.

Histopathology

The histologic analysis may help to differentiate MPA from polyarteritis nodosa and small vessel vasculitis as MPA affects the venules, arterioles, and capillaries. Moreover, the walls of these smaller vessels may contain neutrophilic infiltration.

Findings indicative of glomerulitis include focal necrosis, crescent formation, and the absence of immunoglobulin. Evaluation of the lung tissue demonstrates alveolar capillaritis while the muscle and sural nerve likely exhibit necrotizing vasculitis.

This disease cannot be prevented. However, early diagnosis and treatment can improve outcomes.

Microscopic polyangiitis (MPA) is described as systemic vasculitis that is associated with antineutrophil cytoplasmic antibody (ANCA). This inflammatory disease affects small blood vessels such as the capillaries of the lungs, kidneys, and other organs. While the etiology and pathophysiology are not fully understood, evidence points to the likelihood of genetic predisposition and environmental components. While ANCA is positive in the majority of patients, there are likely other pathogenic mechanisms. Note that there are similar vasculitides associated with ANCA such as granulomatosis with polyangiitis (previously named Wegener granulomatosis) among others [1].

MPA can involve numerous organs, thereby producing a wide spectrum of symptoms. It mainly affects the renal and pulmonary blood vessels. It can cause life-threatening complications such as necrotizing glomerulitis and diffuse alveolar hemorrhage.

Clinical assessment is comprised of the patient and family history, physical examination, and the appropriate tests. The latter includes ANCA studies, complete blood count (CBC), erythrocyte sedimentation rate (ESR), and urinalysis. Furthermore, biopsies of affected organs are obtained. Finally, imaging techniques are performed to evaluate the present manifestations.

The treatment focuses on two key phases, which are remission induction and remission maintenance. Numerous drug trials have been conducted to determine the most effective treatment regimens based on renal involvement, the severity of the overall disease, and other factors. The first phase can be treated with cyclophosphamide and glucocorticosteroids, or with rituximab. The maintenance program can utilize cyclophosphamide, azathioprine, or methotrexate. Since cyclophosphamide is associated with severe side effects, its use should be minimized as much as possible.

Due to the risk of morbidity and mortality associated with MPA, prompt recognition and treatment are paramount in these patients. Aggressive management is typically necessary to prevent organ damage and other severe outcomes.

What is microscopic polyangiitis (MPA)?

This is a rare disease that results from vasculitis, which is inflammation of the blood vessels. MPA can involve various organs such as the kidneys, skin, and lungs. It can cause severe damage to these organs.

What are the causes?

The cause of MPA has not been discovered yet. It is thought that the disease develops due to genetic and environmental factors.

There are ANCA antibodies in the majority of individuals that are affected with this disease. These antibodies attach to certain types of white blood cells, which in turn attach to the walls of blood vessels. This whole process leads to the secretion of substances that cause inflammation.

What are the signs and symptoms?

This disease can affect many organs and organ systems. Therefore, patients can have a wide spectrum of signs and symptoms. Initially, they have:

• Fatigue
• Fever
• Weight loss
• Loss of appetite

The following symptoms may develop:

• Skin: rash with reddish-purple spots
• Abdominal: nausea, vomiting, diarrhea, abdominal pain, and bloody stools
• Kidney: blood in urine
• Lung: shortness of breath, coughing with blood, nosebleeds, sinusitis
• Muscle: loss of strength
• Nerve: abnormal sensation and numbness

Complications may include:

• Kidney failure
• Severe lung disease
• Seizures
• Stroke
• Others

How is it diagnosed?

When an individual presents with the above symptoms, the clinician will obtain the patient and family history, perform a physical exam, and order the appropriate blood tests such as:

• ANCA antibodies
• Complete blood cell count
• Erythrocyte sedimentation rate
• Creatinine
• Urinalysis

Imaging tests are performed depending on which symptoms are present:

• Chest x-ray
• CT scan of affected organs
• Gastrointestinal endoscopy
• Electromyography (EMG)
• Electrocardiography (ECG)

Biopsy (sample tissue) of affected organs is also obtained.

How is it treated?

The treatment is administered into two main phases which are remission induction and remission maintenance:

• Induction: cyclophosphamide and high-dose corticosteroids, or rituximab
• Maintenance: cyclophosphamide, azathioprine, or methotrexate
• Additional medications: glucocorticosteroids, plasma exchange

The treatment regimen depends on the kidney function, how severe the disease is, and other important factors. A combination of medications is typically given.

Can it be prevented?

There is no way to prevent the development of MPA. However, early treatment can help prevent complications.

What is the prognosis?

Treatment significantly improves the outcome in the majority of patients. Also, many patients achieve full remission although some relapse.

It is very important that patients are diagnosed and treated as soon as possible in order to prevent organ damage and complications.

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