Patients suffering from oligoarthritis typically present with symptoms associated with joint inflammation and functional impairment of joints. Affected joints are usually tender, and patients claim arthralgia. Closer inspection may reveal joint swelling or joint effusion, and chronic disease may result in joint deformities. Generally, motion ranges are reduced, and patients describe stiffness. Movements may induce crepitation.

Anamnestic data, symptom onset, distribution patterns as well as disease progression largely depend on the underlying disease. The following examples shall illustrate the diversity of clinical pictures presented by oligoarthritis patients as well as the importance of thorough anamnesis and physical examination.

• OJIA is diagnosed in patients presenting with juvenile idiopathic arthritis if no more than four joints are affected within the first six months after symptom onset. The number of affected joints may increase afterwards, and depending on disease progression, persistent and extended OJIA are distinguished. Knees, ankles and wrists are most commonly compromised. OJIA patients may additionally show symptoms of ocular inflammation, namely of uveitis or iritis. Of note, the latter may not provoke clinical symptoms and may remain undiagnosed unless an ophthalmologic examination is performed.
• Asymmetric oligoarthritis of the lower limbs is typical of RA, although sacroilitis may also be diagnosed. Conjunctivitis, keratitis, episcleritis, uveitis, rash and enthesitis as well as proteinuria and microhematuria are presented by some affected individuals [16]. Diagnosis of RA is largely facilitated if patients report a recent genitourinary or gastrointestinal infection.
• PA may manifest in form of asymmetric oligoarthritis mainly affecting medium to large joints, or in form of symmetric joint inflammation with a predilection for metacarpophalangeal and proximal interphalangeal joints. Moreover, distal interphalangeal joints, spine and sacroiliac joints may be compromised [17]. A medical or family history of psoriasis is of great diagnostic value, and patients may show cutaneous lesions characteristic of psoriasis as well as nail pits, dactylitis and bone lesions at enthesial sites.

Of note, joint inflammation may not induce clinical symptoms at all [7].

• Fever

  Rheumatic fever in a high incidence population: the importance of monoarthritis and low grade fever. Arch Dis Child. 2001; 85: 223-227 Guidelines for the diagnosis of rheumatic fever. Jones criteria, 1992 update. [jiac-j.com]

  The mother of an eight-month-old child with meningitis presented with petechiae on her trunk and lower extremities, fever, and oligoarthritis. [ncbi.nlm.nih.gov]

  During the 2 days prior to his visit to the clinic, the patient said he’d had a fever and night sweats; he denied ocular symptoms, GI complaints, dysuria, or penile discharge. [mdedge.com]

• Fatigue

  Whole-body (systemic) symptoms (such as weakness, fatigue, and fever) are not common. Children with oligoarticular JIA have a high risk for inflammatory eye disease. This can lead to blindness. Eye damage can occur without causing symptoms. [allpeds.com]

• Weakness

  Whole-body (systemic) symptoms (such as weakness, fatigue, and fever) are not common. Children with oligoarticular JIA have a high risk for inflammatory eye disease. This can lead to blindness. Eye damage can occur without causing symptoms. [allpeds.com]

  In September she was referred to the rheumatology outpatient department with a three month history of painful swollen ankles, chest pains, and generalised weakness. Her bowel habit had returned to normal. [pmj.bmj.com]

• Malaise

  One week after the last instillation on June 2014, he was admitted to the hospital after complaining of malaise, pyrexia of 38 °C without associated dysthermia, inflammatory pain and swelling in his knees and foots. [scielo.org.co]

  Case Presentation In February 2008, a 12-year-old girl developed the flu with high fever, malaise, headaches, photophobia, myalgia and arthralgia. PCR and viral culture of a nasopharyngeal swab demonstrated influenza B virus. [ped-rheum.biomedcentral.com]

  Generalized malaise raises the likelihood. [diagnosisdude.com]

  Osteoporosis most common feature with cortical thinning and striations, coarsened trabeculae along with lytic lesions Clinically: (highly variable) Leads principally to bilateral hilar adenopathy, pulmonary infiltrates and skin or eye lesions General: malaise [flinders.edu.au]

  Other systemic symptoms include fever, muscle pain, malaise, headache, nausea, and retro-orbital pain. Symptoms common to all alphavirus infections include rhinorrhoea, sore throat, marked lethargy and backache. [antimicrobe.org]

• Arm Pain

  Olecranon Bursitis Treatment PHASE I - Pain Relief & Protection Managing your pain. Pain is the main reason that you seek treatment for olecranon bursitis. [physioworks.com.au]

• Aspiration

  DNA of Borrelia bavariensis was detected by PCR in 2 aspirates obtained from different joints. Complete recovery was achieved after a 4-week course with amoxicillin. [ncbi.nlm.nih.gov]

  Technique Step 1 involves aspiration of the bursa with an 18-gauge needle. [cfp.ca]

  The swelling should be palpated, and the aspiration point should lie in the area of greatest fluctuance. The needle should not enter the joint capsule and risk seeding infection. The aspirated fluid can then be sent for microscopy and culture. [teachmesurgery.com]

  Joint aspiration and injection. in: Imboden J.B. Hellmann D.B. Stone J.H. CURRENT Diagnosis and Treatment: Rheumatology. 3rd ed. McGraw-Hill, New York2013 Zupancic M. Annamalai A. Brenneman J. Ranatunga S. [amjmed.com]

• Skin Rash

  […] include: Salmonella Shigella Yersinia Campylobacter Chlamydia Streptococcus Viruses such as rubella, Hep B, parvovirus, EBV, CMV, HIV, mumps Disposal Symptoms Diagnosis Action Clear cut septic joint or Septic infected joint Urgent orthopaedic referral Skin [emed.ie]

  Individuals with systemic arthritis may also have a skin rash or enlargement of the lymph nodes (lymphadenopathy), liver (hepatomegaly), or spleen (splenomegaly). [ghr.nlm.nih.gov]

  The rash often comes and goes. It may appear late in the day or in the early morning. It may also be brought on by warm baths or by rubbing or scratching the skin. [uofmhealth.org]

• Arthritis

  It is a general term that describes a condition to be encountered in patients suffering from distinct autoimmune, infectious or idiopathic diseases, e.g., oligoarticular juvenile idiopathic arthritis, reactive arthritis, and psoriatic arthritis. [symptoma.com]

  Arthritis Symptoms and Types Arthritis is characterized by pain, stiffness, and swelling in the joints, as well as by reduced joint mobility. But arthritis appears in different forms, and the causes of arthritis vary by type.. [revolutionhealth.com]

  |Juvenile idiopathic arthritis, persistent oligoarthritis (disorder)|Juvenile idiopathic arthritis, undifferentiated arthritis|Juvenile idiopathic arthritis, undifferentiated arthritis (disorder)|Juvenile reactive arthritis|Juvenile reactive arthritis [averbis.com]

  RF) negative polyarthritis, RF positive polyarthritis, enthesitis-related arthritis, psoriatic arthritis, and undifferentiated arthritis. [medical-dictionary.thefreedictionary.com]

  Inclusion criteria were a diagnosis of JIA and a disease category of persistent oligoarthritis, extended oligoarthritis, rheumatoid factor-negative polyarthritis, psoriatic arthritis, or undifferentiated arthritis. [ncbi.nlm.nih.gov]

• Joint Swelling

  Oligoarticular JIA affects 4 or fewer joints during the first 6 months of the disease. Symptoms tend to be limited to joint swelling and pain. But it can also include uneven bone growth. This can lead to one leg being longer than the other. [allpeds.com]

• Back Pain

  Ankylosing spondylitis (AS) is an inflammatory disease that is characterized by inflammatory back pain and asymmetric peripheral oligoarthritis [1-4]. * Oligoarthritis Caused by Borrelia bavariensis, Austria, 2014 Asymmetric oligoarthritis. [medical-dictionary.thefreedictionary.com]

  ReA was defined as the development of synovitis (either swelling or limitation of joint movement, and pain) in a previously asymptomatic joint, or as inflammatory low back pain (low back pain that was worse at night) within the first 2 months after a [academic.oup.com]

  Schober's test tests the flexion of the lower back. [en.wikipedia.org]

  Huerta-Sil, et al. [14] reported the findings in 50 patients with peripheral arthritis and inflammatory back pain with disease duration of 5.4 years after 3-5 years. [openaccessjournals.com]

  Night pain, morning stiffness, systemic symptoms, recent non-articular infections Sexual history, previous episodes (back pain), rash Examination Joint line tenderness, movements, erythema, local increases in temperature, swelling, loss of joint function [emed.ie]

• Morning Stiffness

  METHODS: Patients with RESULTS: Fifty-nine patients (34 men, 25 women; mean age 32.9 years; median early morning stiffness 30 minutes) were randomized. At baseline, two-thirds reported that they were work impaired. [ncbi.nlm.nih.gov]

  Night pain, morning stiffness, systemic symptoms, recent non-articular infections Sexual history, previous episodes (back pain), rash Examination Joint line tenderness, movements, erythema, local increases in temperature, swelling, loss of joint function [emed.ie]

  Case report A 43-year-old male, electrician, started a peripheral oligoarthritis in the knees, right wrist and left ankle at 6 months of evolution, associated with worsening of physical efforts and morning stiffness less than one hour. [proceedings.blucher.com.br]

  Arthritis caused by inflammation is often associated with joint pain and stiffness, especially after periods of rest or inactivity, such as in morning stiffness. There can be swelling, redness, and warmth around the affected joints. [verywellhealth.com]

  […] and in multiple joints Ongoing inflammation Morning stiffness lasting longer than 30 minutes Fatigue Eye redness Though this is not an exhaustive list, the majority of these will support a rheumatoid arthritis diagnosis. [rheumatoidarthritis.org]

• Arthralgia

  Behçet's disease Arthralgia is seen in up to half of patients, and is usually a non-erosive poly or oligoarthritis primarily of the large joints of the lower extremities. [wordsimilarity.com]

  Arthralgia Arthralgia is the most common but non-specific articular complaint of HIV-positive patients. It tends to occur in the acute phase of the infection and is the result of direct infection of the joint by the virus. [sajr.org.za]

  Although symptomatic therapy may help to relieve arthralgia and to restore motion ranges, cure of the primary disease is the best way to avoid recurrence. [symptoma.com]

  Box 2: Musculoskeletal manifestations of coeliac disease Generalised arthralgia. Muscle weakness and fatigue. Metabolic bone disease: osteomalacia and/or osteoporosis. Clubbing. Muscle cramps and tetany. [pmj.bmj.com]

  Fever, arthralgia/arthritis, chronic arthritis, rash, Finland Karelian fever Fever, arthralgia, rash Russia Table 10. [antimicrobe.org]

• Tingling

  Prescribed azathioprine 100 mg/day and dose of methotrexate was increased to 25 mg/week, as the prednisone to 1 mg/kg/day. 6 months later, the pacient progressed with weakness, tingling in the right leg and worsering of left foot dorsiflexion. [proceedings.blucher.com.br]

  View Article PubMed Google Scholar Petty R, Tingle A: Arthritis and viral infection. J Pediatr. 1988, 113: 948-9. 10.1016/S0022-3476(88)80037-4. [ped-rheum.biomedcentral.com]

• Paresthesia

  Solomon Islands, American Samoa, South pacific Islands Sindbis Fever, rash, arthralgia/arthritis, paresthesias Europe, Africa, Australia, Asia, Philippines Ockelbo Fever, arthralgia/arthritis, rash, chronic joint pain, paresthesias Sweden, Norway Pogosta [antimicrobe.org]

Oligoarthritis may be diagnosed in patients presenting with arthralgia and symptoms indicating an ongoing inflammation in up to four joints, but additional measures may be necessary to identify subclinical joint disease. Laboratory analyses of blood samples, sonography and possibly invasive techniques may be very helpful to that end. Oligoarthritis is typically associated with elevated concentrations of serum inflammatory markers like C-reactive protein, and the erythrocyte sedimentation rate is usually enhanced. Leukocytosis is characteristic of acute inflammatory disorders. Sonography has been successfully used to diagnose subclinical joint inflammation. Eventually, joint biopsies may be carried out to support a tentative diagnosis and to rule out more severe differential diagnoses. Malignancies don't usually provoke oligoarthritis, but neoplasms have occasionally been related with this disorder [18].

In order to identify the underlying disease, target-oriented measures should be chosen based on a list of likely differential diagnoses. In this regards, workup may comprise the following:

• Determination of titers of autoantibodies like rheumatoid factor and anti-cyclic citrullinated peptide antibodies since patients suffering from an autoimmune disease like OJIA or PA often test positive for such antibodies
• Human leukocyte antigen testing, because HLA-B27 genetically predisposes for PA, but is also related to enthesitis-related arthritis, a subtype of juvenile idiopathic arthritis
• Bacteriological culture of blood and synovial fluid samples, with positive results implying septic oligoarthritis
• Molecular biological assays to identify nucleic acids in synovial fluid specimens obtained from RA patients that usually yield negative results in bacteriological culture
• Diagnostic imaging to assess the extent of joint lesions and to reveal additional anomalies of bones and connective tissue
• Urine analysis since renal function impairment is occasionally seen in oligoarthritis patients

It is of utmost important to make a precise diagnosis and to chose an adequate therapeutic regimen to avoid further damage to cartilage, underlying bone and other anatomical structures compromised by joint inflammation. Although symptomatic therapy may help to relieve arthralgia and to restore motion ranges, cure of the primary disease is the best way to avoid recurrence. Although the latter may occur spontaneously - e.g., in case of RA - analgesic and anti-inflammatory medication may mask the underlying disease and cause detrimental diagnostic delays [18].

Symptomatic treatment generally consists in the administration of non-steroidal antiinflammatory drugs that reduce pain and inflammation. In case of persistent or exacerbating arthritis, corticosteroid therapy may be considered. Corticosteroids may be applied per os, parenterally or intraarticularly. Furthermore, disease-modifying antirheumatic drugs like azathioprine, methotrexate, etanercept and infliximab may be administered to control immune-mediated oligoarthritis. However, long-term administration of such drugs may be associated with safety risks, and evidence regarding their effectivity is often scarce. With regards to OJIA, only methotrexate has been shown to be superior to conventional treatment as described before [19]. For treatment of PA, tumor necrosis factor-α inhibitors like etanercept; ustekinumab, a monoclonal antibody targeting interleukin-12 and -23; and secukinumab, an antibody directed against interleukin-17A, may be used [20]. Antibiotics may be indicated in case of RA, although evidence of beneficial effects has only been provided for determined forms of the disease. In this context, antimicrobial treatment is generally recommended for post-streptococcal RA. If arthritis has already developed after genitourinary or gastrointestinal infections, antibiotics are of little use [16].

Surgical interventions are rarely required.

Patients diagnosed with oligoarthritis due to primary disorders potentially associated with ocular and renal damage should undergo regular ophthalmological examinations and urine analyses.

Entities causing oligoarthritis are associated with distinct prognoses:

• OJIA, for instance, may remit (23% within six years) or exacerbate to polyarticular juvenile idiopathic arthritis (50% within that same time frame), as has been shown in a French study [12]. According to that same study, about a third of affected individuals develops joint erosions or uveitis at young ages. Here, high erythrocyte sedimentation rates have been proven to predict a destructive course of the disease. These observations do not support the commonly accepted hypothesis of OJIA being a benign form of juvenile idiopathic arthritis that is outgrown until adulthood. In fact, a metaanalysis has shown OJIA remission rates to range from 36 to 84% [13], and these data imply an uncertain prognosis until further favorable and unfavorable prognostic factors can be identified.
• Spontaneous remission within six months is observed in about 50% of RA patients, but patients may also become asymptomatic at later points in time. About 20% of affected individuals develop chronic arthritis [14].
• PA generally follows a course of apparent remission and recurrence. While adequate treatment may momentarily relieve symptoms, permanent cure is unlikely. In fact, more than half of PA patients develop disabling polyarthritis and present with five or more deformed joints within one or two decades after symptom onset [15]. In this context, oligoarticular onset and lower erythrocyte sedimentation rates have been identified as favorable prognostic factors, whereas polyarthritis and the need for high-dose drug therapy after initial diagnosis predict more rapid progression.

Oligoarthritis may be developed by patients suffering from a wide variety of diseases. Few entities are primarily related to an inflammation of more than one but less than five joints. OJIA, RA and PA as well as undifferentiated arthritis are classic examples of such pathologies. As implied by its designation, the etiology of OJIA remains largely unknown. Genetic predisposition and possibly environmental factors may trigger the onset of an autoimmune response, possibly accompanied by the production of autoantibodies like rheumatoid factor and anti-cyclic citrullinated peptide antibodies [1]. Autoantibodies may also be detected in sera obtained from PA patients, although the assessment of antibody titers is not a sensitive diagnostic tool [2]. PA is considered an autoimmune disease developed by about a fourth of psoriasis patients, but little is known about the triggers of joint inflammation in individuals suffering from scaling cutaneous lesions. Psoriasis-associated skin lesions have been assumed to be provoked by dysregulation of immune cell function and cytokine release following trauma or infection. Cytokines may reach the skeleton and modify the function of cartilage- and bone-forming cells [3]. RA is a type of sterile arthritis commonly triggered by previous genitourinary or gastrointestinal infection with Chlamydia trachomatis or enteric pathogens (e.g., Salmonella spp., Yersinia spp.), respectively [4]. Streptococcus spp. and a wide variety of other bacterial pathogens may also provoke RA, particularly in genetically predisposed individuals. The preceding infection may or may not provoke clinical symptoms. In case it doesn't, the patient is generally diagnosed with undifferentiated arthritis, a clinically similar entity of unknown etiology. Of note, undifferentiated arthritis may also turn into polyarthritis. Indeed, oligoarthritis is characteristic of evolving polyarthritis. In this context, autoimmune disorders like rheumatoid arthritis, seronegative arthritis, and systemic lupus erythematosus as well as infectious diseases like Lyme disease and Whipple disease should be considered [5] [6]. For detailed information on polyarthritis, the interested reader is referred to the respective article.

Although overall incidence and prevalence of oligoarthritis are unknown, the condition is presumably underdiagnosed. High prevalence of subclinical disease has been encountered in a study using sonography to examine both symptomatic and asymptomatic joints of school children in the United States [7]. With regards to epidemiology, major difference between oligoarthritis and polyarthritis is the earlier age of onset of the former.

Additionally, epidemiological data can be provided regarding individual entities associated with this condition.

• Juvenile idiopathic arthritis is the most common rheumatoid disease among the pediatric population, although epidemiological data vary with geographic location. Lowest incidence rates have been reported for Asian populations, e.g., <1 per 100,000 children in Japan, and highest rates have been estimated for Europe, e.g., 23 per 100,000 in Norway [1]. OJIA is among the most common forms of juvenile idiopathic arthritis and thus accounts for major shares of those values. Girls are affected significantly more often than boys. As per definition, symptom onset occurs in patients aged less than 16 years.
• The annual incidence of RA has been estimated to 10 per 100,000 adults, with approximately equal numbers of cases triggered by Chlamydia trachomatis and enterobacteria [8]. Because pathogens triggering RA cannot be identified in all patients and because the condition may be self-limiting, true incidence rates are likely higher. A bimodal age distribution has been reported for post-streptococcal RA: Affected individuals are typically of age 8-14 or 21-37 [9].
• Psoriasis is a common disease and affects about 2% of the general population; about one-fourth of them develops PA, with men and women being affected equally [10]. PA may manifest in form of polyarthritis (60%), oligoarthritis (30%) or distal interphalangeal arthritis (10%) [10]. In most cases, skin lesions precede PA by about a decade. Thus, symptom onset would typically be expected to occur in patients aged 40 years and older. However, PA may also be diagnosed in people who have not yet developed cutaneous symptoms or in pediatric patients, in which case the designation psoriatic juvenile idiopathic arthritis is more commonly used. Of note, regional differences have been reported for this disease [11].

Pathophysiological events provoking oligoarthritis depend on the underlying disease. Still, dysregulation of immune cell function and cytokine release plays a crucial role in the induction and maintenance of oligoarthritis. On the one hand, immune-modulatory environmental influences may trigger the onset of OJIA in genetically predisposed individuals [1]. Distinct populations of immune cells, e.g. T lymphocytes, plasma cells and natural killer cells, may be affected. On the other hand, psoriasis is associated with an activation of dendritic cells in the skin [3]. These cells release interferon-α, a cytokine that promotes a determined subpopulation of dendritic cells to migrate to the lymph nodes. Here, they release interleukin-12 and -23, which affect T cell differentiation and maturation. Eventually, differentiated T cells return to circulation, reach end organs and produce tumor necrosis factor-α, interferon-γ, and interleukin-17, among others. In patients suffering from RA, the immune response triggering the onset of joint inflammation takes place in affected joints. In detail, antigens may spread via the cardiovascular system, reach joints, and induce an immune reaction associated with damage to anatomic structures composing the joint.

Further research is required to clarify the pathogenetic differences between distinct forms of juvenile idiopathic arthritis, to ascertain why psoriasis patients do or don't develop arthritis, and which conditions predispose for RA. Finally, there is a considerable overlap between these entities, since patients may develop psoriatic juvenile idiopathic arthritis and because determined forms of juvenile idiopathic arthritis predispose for RA. The central role of cytokines in all these pathologies is best illustrated by the patients' response to immunomodulatory therapy.

Specific measures can be recommended only for determined forms of oligoarthritis. RA, for instance, is triggered by an infection with Chlamydia trachomatis or enteric pathogens. Accordingly, measures to prevent sexually transmitted diseases and an appropriate general hygiene may reduce the individual risk of RA.

Dietary adjustments, weight loss and physical therapy as well as compliance with therapeutic regimens lower the risks of complications due to joint inflammation.

Oligoarthritis is a descriptive term referring to the simultaneous inflammation of two to four joints in an individual patient. In contrast, individuals suffering from an inflammation of a single joint are diagnosed with monarthritis, and those presenting with even more extensive joint diseases receive a diagnosis of polyarthritis. Distinction between monarthritis, oligoarthritis and polyarthritis may be of diagnostic value. For instance, traumatic joint injury is generally restricted to a single joint or to a determined region of the human body, e.g., the patient's feet or knees, as opposed to systemic autoimmune disease, metabolic disorder or nutrient deficiency, which rather manifest in form of multiple joint lesions. However, these are not exclusion criteria for either form of arthritis. In fact, both monarthritis and polyarthritis may turn into oligoarthritis upon an exacerbation or partial remission, respectively, and vice versa. Thus, it is strongly recommended to consider common causes of monarthritis or polyarthritis when dealing with a patient suffering from oligoarthritis. Anamnestic data, distribution patterns, and clinical symptoms not related to joint inflammation are of utmost importance at the time of establishing a list of potential differential diagnoses.

It is beyond the scope of this article to discuss every possible trigger of oligoarthritis. Thus, general information is provided wherever possible. Additionally, more detailed data are included regarding oligoarticular juvenile idiopathic arthritis (OJIA), reactive arthritis (RA), and psoriatic arthritis (PA), which are common causes of oligoarthritis.

Oligoarthritis refers to the simultaneous inflammation of two to four joints in an individual patient. Oligoarthritis may affect people of any race, both genders and all age groups, but diseases triggering multiple joint inflammation are generally more or less prevalent in determined patient groups. In pediatric patients, the most common cause of oligoarthritis is a specific form of juvenile idiopathic arthritis. However, children may also develop joint inflammation within two months after a genitourinary or gastrointestinal infection, and this form of arthritis is deemed reactive arthritis. The latter may also occur in adults. Furthermore, adult patients with a medical history of psoriasis may be diagnosed with psoriatic arthritis. In sum, a wide variety of autoimmune disorders, infectious diseases, metabolic and endocrine dysbalances as well as neoplasms may provoke oligoarthritis.

Symptoms characteristic of oligoarthritis are joint pain and tenderness of surrounding tissues, joint swelling, stiffness and reduced motion ranges. In severe cases, joint inflammation may provoke permanent deformities. Depending on the underlying disease, patients may show distinct distribution patterns and additional symptoms, and the treating physician will consider all this information when making a diagnosis and choosing an appropriate therapy.

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