Calcinosis. During the period of formation of subcutaneous calcification, children with
JDM may develop high fever, chills, and one or more areas of swelling under the skin.
The inflammation caused by the subcutaneous calcium deposit may be
indistinguishable from that of cellulitis or abscess formation, with warmth, erythema,
and tenderness. Eventually, the lesion may spontaneously extrude calcium, at which
time the fever often subsides. Although this is the natural history of subcutaneous
calcifications, it is often hard to exclude an infectious etiology. If doubt exists, needle
aspiration of the site may be performed and the fluid examined for calcium crystals and
organisms. In the face of uncertainty, it is best to treat for infection with antibiotics
until culture results are available. Incision and drainage or surgical debridement should
be avoided, as the inflamed skin rarely heals satisfactorily. Complete control of the
underlying disease offers the best hope for resolution of calcinosis, although this may
be incomplete or may require many years.
Cardiac Emergencies. Although EKG abnormalities may be seen in up to 50% of
children with JDM, development of myocarditis is uncommon. Involvement of the
conduction system by edema and fibrosis leads to electrical abnormalities and
dysrhythmias.

BEHÇET DISEASE
BD is a rare vasculitis in children, especially in nonendemic areas such as the United
States. BD is the only vasculitis that affects both arteries and veins. The classical
description of BD is a clinical triad consisting of recurrent buccal aphthous ulcers,
recurrent genital ulcers, and uveitis with hypopyon. In addition to these cardinal
features of BD, there are a host of associated clinical manifestations, including arthritis,
neurologic involvement, GI manifestations, vascular/thrombotic disease, and various
dermatologic lesions, including erythema nodosum and necrotic folliculitis.

Clinical Considerations
Recurrent oral ulcerations are the most common presenting sign and ongoing
manifestation of pediatric BD. While ulcerative mucocutaneous lesions are far from
specific for BD, the oral lesions in BD tend to scar, unlike those associated with

inflammatory bowel disease, SLE, chronic oral aphthosis, and Sweet syndrome.
Although oral and genital ulcers may markedly negatively impact quality of life,
there are other less common but more serious complications of BD that may lead to
significant morbidity and even mortality. Ocular disease can be devastating, ultimately
resulting in blindness. GI disease can result in perforation. Neurologic complications
are varied, including headache, meningoencephalitis, idiopathic intracranial
hypertension, and quadriparesis. Psychiatric symptoms, including depression,
personality changes, and memory loss, are also reported. Vascular/thrombotic
complications are a particularly ominous development in BD patients; these can
include dural sinus thrombosis and arterial lesions. In one multinational pediatric BD


series, large-vessel thrombosis was the leading cause of death, carrying a 30%
mortality rate.

Management
The general treatment of BD is similar to other forms of vasculitis discussed in this
chapter, consisting of anti-inflammatory/immunosuppressive agents. Life-threatening
cases of BD may require high-dose systemic corticosteroids and cyclophosphamide.
Thrombotic disease requires anticoagulation in addition to aggressive
immunosuppression.

ARTHRITIS
CLINICAL PEARLS AND PITFALLS
Childhood arthritis lasting 6 weeks or more without alternative etiology is
termed juvenile idiopathic arthritis (JIA).
JIA subtypes differ in the pattern of joints involved, extra-articular
manifestations, and treatment.
Macrophage activation syndrome (MAS) is a severe and potentially lifethreatening complication of systemic JIA (sJIA).
JIA is frequently treated with disease-modifying and biologic agents that may

suppress the immune system.
Arthritis is a clinical finding of joint inflammation characterized by warmth,
swelling, tenderness, and/or restriction of joint movement, often accompanied by
prolonged morning stiffness. Arthritis is a common childhood finding and has many
causes, including infection and autoimmunity. Infectious arthritis may be caused by a
multiplicity of pathogens, including bacteria, viruses, and fungi. Bacterial arthritis, also
known as septic arthritis, is addressed in Chapters 46 Limp and 94 Infectious Disease
Emergencies . In addition, an inappropriately self-directed immune response triggered
by infection may lead to a post-infectious reactive arthritis. While this class of arthritis
is typically self-limited, treatment, usually with NSAIDs, may be needed to ameliorate
symptoms. On occasion postinfectious inflammatory arthritis recurs or persists, leading
to (or unmasking) a chronic arthritis akin to more typical juvenile inflammatory
arthritis. When childhood arthritis persists and no alternative etiology is discovered, it
is termed JIA. In this chapter, we will focus our discussion on JIA. Lyme arthritis, a
late manifestation of systemic infection with Borrelia, is discussed in Chapter 94
Infectious Disease Emergencies .

JUVENILE IDIOPATHIC ARTHRITIS


Current Evidence
JIA, formerly known as juvenile rheumatoid arthritis (JRA), is now the most common
pediatric rheumatologic disease in the developed world, having replaced acute
rheumatic fever. JIA occurs in all races and ethnic groups, with a reported prevalence
that varies from 30 to 400 per 100,000 children depending upon the population studied
and the diagnostic techniques used. In the United States alone, JIA affects at least
100,000 children.
A variety of different classification systems for JIA exists, but in the absence of a
clear-cut understanding of the pathogenesis of arthritis, the preferred is the
International League for Associations in Rheumatology (ILAR) classification system (

Table 101.10 ). It includes the following subtypes of arthritis: polyarticular,
oligoarticular (persistent and extended), and sJIA as well as psoriatic arthritis,
enthesitis-related arthritis (ERA), and undifferentiated arthritis ( Table 101.11 ).
Persistent unexplained arthritis of one or more joints lasting more than 6 weeks in
children younger than 16 years of age will be referred to as JIA, though this is an
umbrella term that overarches the more specific subtypes. In all cases, because there
are no laboratory abnormalities specific for JIA, the diagnosis is made clinically after
exclusion of other infectious, inflammatory, and traumatic conditions.
The etiology of JIA is not known and is likely multifactorial. Further, systemic JIA is
more aptly characterized as an autoinflammatory disorder (or disorder of the innate
immune system), whereas the other subtypes are more likely to be autoimmune (or
disorder of the adaptive immune system). It is useful conceptually to divide the
pathogenesis of inflammatory arthritis into an initiating phase and a perpetuating phase.
Various events, particularly viral infections, may trigger articular inflammation. For a
variety of reasons related to both the host and the inciting event, a process that is selflimited in most children leads to ongoing inflammation in others. This inflammation is
characterized by abnormal tissue and circulating levels of proinflammatory cytokines
(including interleukin [IL]-1, IL-6, tumor necrosis factor [TNF], and interferon-γ)
leading to activation of lymphocytes and infiltration of synovium. In fact, conditions
labeled as JIA most likely represent a final common pathway for many different types
of synovitis in view of the widely disparate characteristics of the different subtypes of
JIA.

Clinical Considerations
JIA is characterized by wide demographic and clinical variety, so the condition has
been divided into subtypes based on these factors and on the pattern of the disease
during the first 6 months following onset ( Table 101.11 ). These varieties, in turn, are
treated in different ways, and are associated with different complications. Until a
pathophysiologically based means of classifying and distinguishing these subtypes of
JIA becomes available, what is probably several discrete conditions will continue to be



grouped on the basis of clinical features. The remainder of this chapter will use the
ILAR classification scheme for JIA.
TABLE 101.10
CLASSIFICATION SYSTEMS FOR JUVENILE ARTHRITIS
Comparison of current classification systems for chronic arthritis in children,
showing differing names for similar types of arthritis in parallel columns.
ACR

ILAR

EULAR

Juvenile rheumatoid Juvenile idiopathic arthritis
arthritis

Juvenile chronic arthritis

Systemic onset
Polyarticular onset

Systemic arthritis
RF-negative polyarthritis

Systemic onset
Polyarticular onset

Pauciarticular onset

RF-positive polyarthritis

Oligoarthritis

Juvenile rheumatoid arthritis
Pauciarticular onset

Type 1

Type 2

Persistent
Extended
Psoriatic arthritis

Juvenile psoriatic arthritis

Enthesitis-related arthritis

Juvenile ankylosing
spondylitis

Undifferentiated arthritis
ACR, American College of Rheumatology; ILAR, International League of Associations for Rheumatology;
EULAR, European League Against Rheumatism.

TABLE 101.11
SUBGROUPS OF JUVENILE IDIOPATHIC ARTHRITIS