A 10-year-old male is brought to the primary care office by his parents who report that their son has had progressive low back pain in the morning for approximately four months. This pain is also aggravated by physical activity such as bending or wrestling but the patient denies any trauma that may have caused this pain. The patient also denies any numbing or weakness of the lower extremities, and there is no history of bladder or bowel incontinence.

The symptoms have been partially alleviated with ibuprofen and his parents have noted that their son feels better after soaking in a warm bath. Further history reveals the patient also had progressive left knee pain and swelling several months before his complaints of low back pain.



The patient’s past medical history is significant for a febrile illness nine months prior to his office visit. This illness consisted of a fever of 103ºF and a rash that lasted three days. At the time, the patient was diagnosed as having a viral syndrome. At the age of four, the patient had an episode of streptococcal pharyngitis that was treated with appropriate antibiotics. Immunizations are up to date. The patient denies a history of tick-borne diseases, chest pain, palpitations or shortness of breath.

The physical exam reveals a well-nourished and well-developed male in no apparent distress. His vitals include a weight of 98 pounds in a gown. He is 4’6’’ tall without shoes, has an oral temperature of 98.4ºF, blood pressure of 112/72, and respirations of 12 breaths/minute that are unlabored. A lung exam demonstrates normal chest expansion and diaphragmatic excursion and lungs that are clear to auscultation. The patient has a regular heart rate and rhythm without murmurs or gallops. His abdomen is without tenderness, mass or organomegally.

Inspection of the back reveals a well-aligned spine without erythema, mass or deformity. Palpation of the back reveals warmth and tenderness over the lumbar spine without mass, paraspinal spasm or tenderness. The patient has full range of motion of the spine. He does experience pain over the lumbar spine with all motion and this pain is only relieved when the child resumes neutral position of the spine.

The exam of the lower extremities reveals swelling, erythema and warmth of the left knee. He has full passive and active ranges of motion of the knees but complains of pain and stiffness in the left knee. Further testing for meniscal and ligament injury of the knees is unrevealing. Further exam of the lower and upper extremities is without abnormalities. Laboratory testing reveals a positive HLA-B27 and an elevated sedimentation rate while antinuclear antibodies (ANAs) and rheumatoid factor are negative. Plain films of the lumbar sacral spine are normal.

Which of the following is the most likely diagnosis?
A. Ankylosing spondylitis
B. Lyme disease
C. Acute rheumatic fever
D. Juvenile rheumatoid arthritis

A Closer Look At The Differential Diagnosis
A. Ankylosing spondylitis is not the correct answer. Ankylosing spondylitis is a chronic inflammatory disease of the axial skeleton with the typical age of onset in the late teens or early 20s. It also affects men more than women. The presentation of back pain and decreased range of motion is gradual with progression of symptoms in a cephalad direction. Thoracic curvature is exaggerated while the lumbar curve is flattened and chest expansion is limited secondary to costovertebral joint involvement.

One may see peripheral joint involvement in less than 25 percent of ankylosing spondylitis cases. Radiographic findings in early disease note changes in the sacroiliac joints. Progressive demineralization of the vertebral bodies and calcification of the ligaments of the spine are findings in advanced disease. Laboratory findings include a positive HLA-B27 in 90 percent of patients and an elevated ESR in 85 percent of patients respectively.

B. Lyme disease is not the correct answer. Lyme disease is an infectious disease caused by the spirochete Borrelia burgdorferi that is transmitted to humans by ixodid ticks. Lyme disease typically presents in three stages with some overlap. The first stage involves localized infection with the characteristic erythema migrans, fever, chills and myalgias lasting approximately three to four weeks. Stage 2 of the disease, occurring days to weeks after infection, involves dissemination of the disease that can affect the skin, central nervous system and the musculoskeletal system. Symptoms include rash, migratory pain in joints, tendons and muscles, Bell’s palsy, aseptic meningitis, encephalitis, irritability and personality changes.

Stage 3 occurs months to years after inoculation and again affects the musculoskeletal and neurological systems. Approximately 60 percent of individuals that have Lyme disease develop musculoskeletal symptoms. These symptoms include joint and periarticular pain without objective findings, chronic or recurrent arthritis of the large joints, and chronic synovitis. Laboratory diagnosis includes serological testing, which includes ELISA and Western Blot testing that is used in conjunction with the patient’s history signs and symptoms to confirm the diagnosis.

Dr. Auth is the Clinical Editor of Diagnostic Dilemmas. He is also a physician assistant and is the Director of the Drexel Hahnemann Physician Assistant Program at Drexel University in Philadelphia.

C. Acute rheumatic fever is not the correct answer. Acute rheumatic fever is an immune response to untreated group A beta-hemolytic streptococcus with symptoms occurring two to six weeks after infection. The presentation can include: arthritis, which is migratory and involves large joints but rarely the vertebrae; erythema marginatum; subcutaneous nodules; and carditis revealed as a new cardiac murmur. The murmur is secondary to mitral regurgitation or aortic regurgitation resulting from edema from the mitral valve. Voltage changes on serial electrocardiograms can be useful to evaluate carditis of acute rheumatic fever.

D. Juvenile rheumatoid arthritis (JRA) is the correct answer. Inflammation of the synovial membrane occurs in JRA. Progressive inflammation may lead to progressive joint damage. When children less than 16 years of age have had presenting symptoms for at least six weeks and all other causes of arthritis have been ruled out, one may make the diagnosis of JRA. The cause of JRA is unknown and is not considered hereditary or influenced by social or dietary factors. However, studies have identified that some children may have a genetic predisposition that is influenced by an unknown infectious agent.1

Several subtypes of JRA exist. These subtypes include pauciarticular arthritis, which presents in children older than eight and more frequently in males. These patients typically present with asymmetrical involvement of the lower extremities with the knee being the most common joint involved. Morning stiffness and pain are accompanied by a progressive decrease in motor performance with physical activity. Often, you will note involvement of the lower spine and be aware that one may confuse this with ankylosing spondylitis. However, radiographs reveal that the sacral spine is spared in JRA. Laboratory findings for older children are usually normal but keep in mind that symptomatic children may have a positive HLA-B27 while having a negative rheumatoid factor and ANAs.

Pauciarticular JRA in younger children (the peak age of onset is two years old) affects females more than males. There is often localized joint swelling of the lower extremities without pain and this condition is rarely destructive to the joints. However, growth differences can occur in affected joints. Chronic uveitis is also a risk for these children. Again, laboratory tests are typically normal but greater than 50 percent of children have positive ANAs.

Mr. Stream is an Instructor at the Drexel University Hahnemann Physician Assistant Program.

Other subtypes of JRA include polyarticular JRA in which five or more joints are involved. In these cases, the small joints of the hands and feet are more frequently involved. Females are affected more than males and the age of onset typically ranges between 9 to 16 years of age. Approximately 8 percent of children with polyarticular JRA have a positive rheumatoid factor and for those that have a negative rheumatoid factor, 25 percent have positive ANAs.

Systemic onset JRA is the least common but the most debilitating form of JRA. Both sexes are affected equally and the onset tends to occur before patients turn 16 years. Children present with a febrile illness (about 103ºF) that lasts several weeks with an erythematous macular rash, lymphadenopathy, splenomegaly and hepatomegaly. Symptoms may not evolve until weeks or months after the acute illness, and the symptoms may include severe polyarticular involvement. Systemic onset JRA can also include growth retardation, bony fusion of the cervical spine, pericarditis and pleuritis. Uveitis rarely occurs.

How To Manage JRA
First-line treatment of JRA begins with non-steroidal antiinflammatory drugs to control symptoms and prevent joint damage. Disease remission occurs in most children with this treatment approach.
However, predicting the outcome for each case is not possible and some children require disease-modifying drugs such as hydroxychloroquine, methotrexate, entanercept and infliximab. Steroid preparations including localized injection or oral administration may be necessary in severe cases. However, clinicians must be cognizant of the potential side effects (including growth retardation) of this class of medications when considering long-term use. Appropriate dietary calcium is recommended to prevent osteopenia, especially among those requiring systemic corticosteroid therapy.

Clinicians may refer patients to occupational and physical therapy in order to improve quality of life through strengthening exercises and adaptations in daily activities of living. In severe cases, splinting and joint replacements are necessary. Social services and psychological counseling are useful for children dealing with the chronic disease.

In Conclusion
According to the American College of Rheumatology, approximately one in every 1,000 children develop some type of juvenile arthritis.2 Clinical features for each disease are distinct but overlapping signs, symptoms and laboratory findings can confound the exact diagnosis.1 Keys to improve diagnosis include identifying inflammation, the number and location of the joints affected along with appropriate interpretation of diagnostic studies.3

Clinical Editor: Patrick Auth, PA-C, PhD