Paediatric Rheumatology Flashcards
Juvenile Idiopathic Arthritis
Juvenile idiopathic arthritis (JIA) refers to a condition affecting children and adolescents where autoimmune inflammation occurs in the joints. It is diagnosed where there is arthritis without any other cause, lasting more than 6 weeks in a patient under the age of 16. It has also been known as juvenile chronic arthritis and juvenile rheumatoid arthritis.
The key features of inflammatory arthritis are joint pain, swelling and stiffness.
There are a number of subtypes of juvenile idiopathic arthritis. Each has individual characteristics and is associated with different serology (blood tests). It is worth remembering five key subtypes:
Systemic JIA
Polyarticular JIA
Oligoarticular JIA
Enthesitis related arthritis
Juvenile psoriatic arthritis
Juvenile idiopathic arthritis
Juvenile idiopathic arthritis (JIA) refers to a condition affecting children and adolescents where autoimmune inflammation occurs in the joints. It is diagnosed where there is arthritis without any other cause, lasting more than 6 weeks in a patient under the age of 16. It has also been known as juvenile chronic arthritis and juvenile rheumatoid arthritis.
The key features of inflammatory arthritis are joint pain, swelling and stiffness.
There are a number of subtypes of juvenile idiopathic arthritis. Each has individual characteristics and is associated with different serology (blood tests). It is worth remembering five key subtypes:
Systemic JIA
Polyarticular JIA
Oligoarticular JIA
Enthesitis related arthritis
Juvenile psoriatic arthritis
Systemic JIA
This is also knowns as Still’s disease. This is a systemic illness that can occur throughout childhood in boys and girls. It is an idiopathic inflammatory condition. Typical features are:
Subtle salmon-pink rash
High swinging fevers
Enlarged lymph nodes
Weight loss
Joint inflammation and pain
Splenomegaly
Muscle pain
Pleuritis and pericarditis
Antinuclear antibodies and rheumatoid factors are typically negative. There will be raised inflammatory markers, with raised CRP, ESR, platelets and serum ferritin.
A key complication is macrophage activation syndrome (MAS), where there is severe activation of the immune system with a massive inflammatory response. It presents with an acutely unwell child with disseminated intravascular coagulation (DIC), anaemia, thrombocytopenia, bleeding and a non-blanching rash. It is life threatening. A key investigation finding is a low ESR.
TOM TIP: Think of Still’s disease (systemic JIA) when a patient presents with a salmon-pink rash, fevers and joint pain. In children that have fevers for more than 5 days, the key non-infective differentials to remember are Kawasaki disease, Still’s disease, rheumatic fever and leukaemia.
Polyarticular JIA
Polyarticular JIA involves idiopathic inflammatory arthritis in 5 joints or more. The inflammatory arthritis tends to be symmetrical and can affect the small joints of the hands and feet, as well as the large joints such as the hips and knees. There are minimal systemic symptoms, but there can be mild fever, anaemia and reduced growth. Systemic symptoms are mild, unlike systemic onset JIA.
Polyarticular JIA is the equivalent of rheumatoid arthritis in adults. Most children are negative for rheumatoid factor and are described as “seronegative”. When rheumatoid factor is positive they are described as “seropositive”. Seropositive patients tend to be older children and adolescents and the disease pattern is more similar to rheumatoid arthritis in adults.
Oligoarticular JIA
This is also knowns as pauciarticular JIA. It involves 4 joints or less. Usually it only affects a single joint, which is described as a monoarthritis. It tends to affect the larger joints, often the knee or ankle. It occurs more frequently in girls under the age of 6 years.
A classic associated feature with oligoarticular JIA is anterior uveitis. Patients should be referred to an ophthalmologist for management and follow up of uveitis.
Patients tend not to have any systemic symptoms and inflammatory makers will be normal or mildly elevated. Antinuclear antibodies are often positive, however rheumatoid factor is usually negative.
Enthesitis-Related Arthritis
Enthesitis-related arthritis is more common in male children over 6 years. It can be thought of as the paediatric version of the seronegative spondyloarthropathy group of conditions that affect adults. These conditions are ankylosing spondylitis, psoriatic arthritis, reactive arthritis and inflammatory bowel disease-related arthritis. Patients have inflammatory arthritis in the joints as well as enthesitis.
An enthesis (pleural: entheses) is the point at which the tendon of a muscle inserts into a bone. Enthesitis is inflammation of this insertion point. Enthesitis can be caused by traumatic stress, such as through repetitive strain during sporting activities, or can be caused by an autoimmune inflammatory process. An MRI scan of the affected joint can demonstrate enthesitis, but cannot distinguish between an enthesitis due to stress or an autoimmune process.
The majority of patients with enthesitis-related arthritis have the HLA B27 gene. This is a particular genetic variant of the human leukocyte antigen (HLA). When assessing patients for enthesitis-related arthritis, consider signs and symptoms of psoriasis (psoriatic plaques and nail pitting) and inflammatory bowel disease (intermitted diarrhoea and rectal bleeding). Patients with enthesitis-related arthritis are prone to anterior uveitis, and should see an ophthalmologist for screening, even if they are asymptomatic.
Patients with enthesitis will be tender to localised palpation of the entheses. Therefore it is worth palpating key areas to elicit tenderness of the entheses:
Interphalangeal joints in the hand
Wrist
Over the greater trochanter on the lateral aspect of the hip
Quadriceps insertion at the anterior superior iliac spine
Quadriceps and patella tendon insertion around the patella
Base of achilles, at the calcaneus
Metatarsal heads on the base of the foot
Juvenile Psoriatic Arthritis
Psoriatic arthritis is an seronegative inflammatory arthritis associated with psoriasis, the skin condition. The pattern of joint involvement varies. Patients can have a symmetrical polyarthritis affecting the small joints similar to rheumatoid, or an asymmetrical arthritis affecting the large joints in the lower limb.
Juvenile psoriatic arthritis is associated with several signs on examination:
Plaques of psoriasis on the skin
Pitting of the nails (nail pitting)
Onycholysis, separation of the nail from the nail bed
Dactylitis, inflammation of the full finger
Enthesitis, inflammation of the entheses, which are the points of insertion of tendons into bone
Management of Juvenile Idiopathic Arthritis
The management should be coordinated by a specialist in paediatric rheumatology, with a specialist multi-disciplinary team. The aim of treatment is to reduce inflammation within the joints, minimise symptoms and maximise function.
Medical treatment depends on the severity and response, and involves:
NSAIDs, such as ibuprofen
Steroids, either oral, intramuscular or intra-artricular in oligoarthritis
Disease modifying anti-rheumatic drugs (DMARDs), such as methotrexate, sulfasalazine and leflunomide
Biologic therapy, such as the tumour necrosis factor inhibitors etanercept, infliximab and adalimumab
Ehlers-Danlos syndrome
Ehlers-Danlos syndrome (EDS) is a group of genetic conditions involving defects in collagen, causing hypermobility in the joints and abnormalities in the connective tissue of the skin, bones, blood vessels and organs.
TOM TIP: Marfan syndrome is a critical differential diagnosis for hypermobility and needs to be excluded. Key features of Marfan syndrome are a high arch palate, arachnodactyly (long fingers) and increased arm span to body height ratio.
Types of Ehlers-Danlos syndrome
Hypermobile Ehlers-Danlos syndrome is the most common and least severe type of Ehlers-Danlos syndrome (although it still causes significant disability and psychosocial issues). The key features are joint hypermobility and soft and stretchy skin. A single gene for hypermobile EDS has not been identified. It appears to be inherited in an autosomal dominant pattern.
Classical Ehlers-Danlos syndrome features remarkably stretchy skin that feels smooth and velvety. There is severe joint hypermobility, joint pain and abnormal wound healing. Lumps often develop over pressure points, such as the elbows. Patients are prone to hernias, prolapses, mitral regurgitation and aortic root dilatation. Inheritance is autosomal dominant.
Vascular Ehlers-Danlos syndrome is the most severe and dangerous form of EDS, where the blood vessels are particularly fragile and prone to rupture. Patients have characteristic thin, translucent skin. Other features include gastrointestinal perforation and spontaneous pneumothorax. Patients are monitored for vascular abnormalities and told to seek urgent medical attention for sudden unexplained pain or bleeding. Inheritance is autosomal dominant.
Kyphoscoliotic Ehlers-Danlos syndrome is characterised initially by poor muscle tone (hypotonia) as a neonate and infant, followed by kyphoscoliosis as they grow. There is significant joint hypermobility. Joint dislocation is common. Inheritance is autosomal recessive.
TOM TIP: It is worth being familiar with relatively common hypermobile Ehlers-Danlos syndrome and remembering some key features of the other types to spot them in your exams. Remember the extremely stretchy skin and severe joint hypermobility associated with classic EDS, and the thin translucent skin and blood vessel rupture associated with vascular EDS.
Presentation of Ehlers-Danlos syndrome
The most common presenting feature of hypermobile EDS is joint pain and hypermobility. However, it is a multi-system disorder, and symptoms commonly occur across multiple areas of the body:
Joint dislocations (e.g., shoulders or hips)
Soft and stretchy skin
Stretch marks (striae)
Easy bruising
Poor wound healing
Bleeding
Chronic pain (can be widespread)
Chronic fatigue
Headaches
Autonomic dysfunction (e.g., POTS)
Gastro-oesophageal reflux
Abdominal pain
Irritable bowel syndrome
Menorrhagia and dysmenorrhea
Premature rupture of membranes in pregnancy
Urinary incontinence
Pelvic organ prolapse
Temporomandibular joint dysfunction
Postural orthostatic tachycardia syndrome (POTS) can occur with hypermobile Ehlers-Danlos syndrome, resulting from autonomic dysfunction. Significant tachycardia occurs on sitting or standing, and symptoms include presyncope (lightheadedness), syncope (loss of consciousness), headaches, disorientation, nausea and tremor.
Beighton Score
The Beighton score is used to assess for hypermobility and support the diagnosis. One point is scored for each side of the body, with a maximum score of 9, if the patient can:
Place their palms flat on the floor with their straight legs (scores only 1)
Hyperextend their elbows
Hyperextend their knees
Bend their thumb to touch their forearm
Hyperextend their little finger past 90 degrees
TOM TIP: It is worth learning and remembering to use the Beighton score to assess patients for hypermobility.
Managing Ehlers-Danlos syndrome
Hypermobile Ehler-Danlos syndrome is a clinical diagnosis assisted by the Beighton score. Genetic testing is helpful in the other subtypes of EDS.
There is no cure for EDS. Management focuses on maintaining healthy joints, managing symptoms, supporting daily activities and monitoring for complications. This will involve:
Follow up with relevant specialists depending on the associated complications
Physiotherapy to strengthen and stabilise the joints and maintain good posture
Occupational therapy to maximise function
Moderating activity to minimise flares
Psychology may be required to support wellbeing
Hypermobility in the joints leads to additional wear and tear on the joint, resulting in premature osteoarthritis.
Henoch-Schonlein Purpura
Henoch-Schonlein Purpura (HSP) is an IgA vasculitis that presents with a purpuric rash affecting the lower limbs and buttocks in children. Inflammation occurs in the affected organs due to IgA deposits in the blood vessels.
It affects the skin, kidneys and gastro-intestinal tract. The condition is often triggered by an upper airway infection or gastroenteritis. It is most common in children under the age of 10 years.
The four classic features are:
Purpura (100%),
Joint pain (75%),
Abdominal pain (50%)
Renal involvement (50%)
The rash is caused by inflammation and leaking of blood from small blood vessels under the skin, forming purpura. Purpura are red-purple lumps under the skin containing blood.
