Childhood Rheumatic Diseases
Thomas J. A. Lehman
The rheumatic diseases of childhood represent a diverse group, both clinically and immunologically. Their etiologies are varied and their pathogeneses are unclear. Lyme disease and acute rheumatic fever are the only two rheumatic diseases of childhood with a known infectious etiology, that is, Borrelia burgdorferi and group-A β hemolytic streptococci, respectively.
Most childhood rheumatic diseases result from a combination of genetic predisposition, autoimmunity, and unknown environmental factors. Most of these diseases are treated with a broad range of anti-inflammatory or immunosuppressive medications.
PREVALENCE
Reactive arthritis (acute episodes of arthritis and arthralgia following an infectious illness) is common in childhood, but chronic rheumatic diseases are infrequent. Nonetheless, there are more than 250,000 children with arthritis in the United States. Prevalence estimates are confused between the number of children with juvenile rheumatoid arthritis (JRA) (100,000) and the number of children with any form of arthritis (250,000). This dichotomy is responsible for an ongoing process of redefinition and reclassification.
The term JRA is being replaced by the term juvenile idiopathic arthritis (JIA). However, it is important to remember that JIA does not describe a specific disease; rather, it is an umbrella term covering various forms of childhood arthritis that may have different etiologies, natural histories, best therapies, and underlying genetic predispositions. At present, eight distinct subtypes of JIA have been described, and it is expected that more subtypes will be delineated before the redefinition is complete.
With this new definition, the spondyloarthropathies and many other types of arthritis that currently fall outside the spectrum of JRA will be included in JIA. This is unfortunate because the etiology, natural history, and best therapy for spondyloarthropathies are distinct. Officially, however, spondyloarthropathies will be termed enthesitis-associated arthritis, which will be a subtype of JIA.
JIA (including what was previously termed JRA and spondyloarthropathies), Henoch-Schönlein purpura, Kawasaki’s disease, systemic lupus erythematosus (SLE), dermatomyositis, and scleroderma are the most common forms of chronic arthritis in childhood.
CLINICAL MANIFESTATIONS, DIAGNOSIS, AND DIFFERENTIAL DIAGNOSISA careful history and physical examination are crucial to the proper diagnosis of childhood arthritis. The examining physician must have a clear knowledge of the differential diagnosis because children are often poor historians. A useful algorithm is illustrated in Table 36-1. The examining physician must determine whether inflammation is present (i.e., objective pain, swelling, warmth, or limitation of motion), whether the inflammation is articular or periarticular, and whether the inflammation is acute or chronic.
Table 36-1 Common Forms of Chronic Synovitis in Childhood | ||
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I. WHEN NO OBVIOUS INFLAMMATION IS PRESENT
Growing pains. This is the most common and most misused diagnosis for musculoskeletal pain in childhood. The true syndrome of “growing pains” occurs in young children, peaking at the age of 4 to 5 years. Pain occurring in the popliteal fossa is a
classic example. It is relieved by gentle massage or by reassurance and occurs only at night. Pain during the day does not represent growing pains. Growing pains are benign and self-limiting. Often, there is a family history of similar complaints, which may aid in the diagnosis. Growing pains are typically relieved by acetaminophen and do not require specific therapy.
Psychogenic rheumatism. Joint pains and fatigue occur frequently as somatization disorders. It is worrisome when a child is unable to attend school or participate in normal activities despite an unremarkable physical and laboratory evaluation. Some children respond to gentle reassurance, but for others the complaints of pain mask a major psychological disorder. Children with persistent complaints of pain despite normal findings should be evaluated carefully by an experienced pediatric rheumatologist to exclude undiagnosed illness. If the physician is not able to find an objective source of the complaints of diffuse aches and pains with fatigue in a child, he or she should also consider the possibility that the child may be reacting to problems within the family. Often the families of such children reject an immediate recommendation of psychological counseling. However, physicians who establish a trusting relationship with the family may be able to bring about gradual resolution of the complaints or an acceptance of the need for psychological intervention.
Reflex neurovascular dystrophy represents an extension of psychogenic rheumatism in which the somatization has progressed to include hyperesthesias, often with mottled skin coloring and vascular instability. Reflex neurovascular dystrophy often begins with a well-documented injury that fails to improve. The syndrome typically occurs in “perfect” children under excessive parental pressure. Any psychological stress may initiate this syndrome. Excessive pressure to excel in sports or other activities is the most common cause, but sexual abuse is another well-recognized cause. Although the specific complaints may be resolved with intensive physical and occupational therapy, failure to resolve the underlying psychological issues often results in recurrence of similar problems within a short period.
II. PERIARTICULAR INFLAMMATION
Children with periarticular (i.e., soft tissue, tendon, ligamentous, or bursal) inflammation must be carefully evaluated for associated osseous disorders.
Orthopedic disorders. Acute periarticular pain may result from a stress fracture or osteomyelitis. Young children with fractures may not report trauma. Battering must be considered when a child presents with unsuspected fractures. Bone scan is often helpful in the evaluation of these entities.
Neoplastic disorders associated with infiltration of the bone marrow include leukemia, lymphoma, and neuroblastoma. All these conditions may present with difficulty in walking or with “joint pains.” Disproportionate anemia, thrombocytopenia, hyperuricemia, lymphadenopathy, or hepatosplenomegaly should prompt further investigation and bone marrow aspiration.
Rheumatic disorders. The juvenile spondyloarthropathies often present with both periarticular and articular inflammation. The periarticular manifestations may predominate, but articular inflammation is usually present. Lumbar stiffness, enthesitis, and heel pain should be specifically sought. Often, these children are thought to have recurrent sprains or strains. The possibility of arthritis is often incorrectly dismissed by inexperienced physicians because the erythrocyte sedimentation rate (ESR) is normal.
III. ARTICULAR INFLAMMATION
Children with true articular inflammation must be subdivided depending on whether the inflammation is acute or chronic (of more than 6-week duration).
Acute articular inflammation
Infection. An acutely inflamed joint must be considered septic until proven otherwise. Staphylococci, streptococci, and Hemophilus influenzae are frequent causes of septic arthritis in childhood. Lyme disease is a systemic disease, usually presenting as arthritis in children and is frequent in areas where Ixodes ticks are endemic. Not infrequently, Lyme disease may involve several joints simultaneously. Septic arthritis typically presents with a single inflamed joint accompanied by fever and an elevated ESR. It is less common but not impossible for
other infectious agents to involve multiple joints. Children with reactive arthritis may also have an associated infectious process and multiple joints may be involved (see in the subsequent text).
Reactive arthritis may occur as a result of bacterial, viral, or fungal infections. Toxic synovitis is the most common type of reactive arthritis in children. The typical child with toxic synovitis is aged 3 to 5 years. He or she is well except, perhaps, for symptoms of an upper respiratory infection the prior evening. The following morning, the child awakens unable to walk, with a decreased range of mobility in one hip. There is only low-grade or no fever, without significant elevation of the white blood cell count or ESR. Unless an experienced physician is comfortable with the clinical picture, the joint must be aspirated to rule out bacterial infection. In experienced centers, ultrasonography may be adequate to discriminate a septic joint on the basis of the characteristics of the joint fluid and the degree of reaction in the surrounding tissues. The joint symptoms of a child with toxic synovitis typically begin to improve within a few hours; in contrast, those of a child with a truly septic hip often rapidly worsen. Reactive arthritis often follows the acute infectious episode and antibiotic therapy is unnecessary, but the infectious agent may still be present and the patient may require treatment even if the agent is not found in the inflamed joint (e.g., reactive arthritis in association with a gonococcal infection).
Poststreptococcal reactive arthritis deserves special consideration. This disorder is not classified as acute rheumatic fever because it does not fulfill the Jones’s criteria. Nonetheless, children with arthritis and elevated ESRs should receive antibiotic prophylaxis following a documented streptococcal infection (see Chapter 49). Cardiac damage has been found with subsequent streptococcal infections in some children who did not receive such long-term prophylaxis.Related posts:
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