Fever, rash and migratory polyarthralgia

Key Points

THE CASE

A previously healthy 12-year-old boy presents to an emergency department (ED) in southern Ohio in October with a chief complaint of fever and rash. The patient has had subjective fever for 3 days with weakness, malaise, anorexia, and decreased activity. He had emesis followed by diarrhea on the second day.

He complains of diffuse myalgias and migratory arthralgias, which began in the right shoulder and have progressed to involve the cervical spine and all joints of the extremities bilaterally, but sparing the hips. A rash developed bilaterally on his inner thighs at the onset of illness, then spread to involve his forearms, abdomen, trunk, and hands, sequentially.

Worsening symptoms

The patient returns to the ED 2 days later with persistent fever, worsening arthralgia, and new swelling in the left knee. He is unable to ambulate and has decreased oral intake. Both wrists and multiple finger joints have become painful. The pain is greatest in the right wrist and left knee. Further questioning reveals that the patient traveled to southern Kentucky about 4 weeks ago for a Labor Day camping trip with his family. He recalls having found ticks on his clothing but not on his skin. He denies alcohol or drug use. The family has numerous pets including 1 hermit crab, 1 African clawed frog, 2 lizards, 1 domestic white rat, 1 python, and a tank of tropical fish. They had 2 dogs, but both recently died of unknown causes. The patient denies any animal bites. He reports that he has a girlfriend, but he denies any sexual activity. His temperature is 38.9°C, blood pressure is 100/72 mmHg, pulse is 110 beats per minute, and respiratory rate is 30 breaths per minute. The rash has progressed, with an increased number of well-demarcated, macular, papular, and vesicular lesions involving the extremities, especially the palms and soles. The lesions are blanching and nonpruritic. The left knee is warm, nonerythematous, and swollen with ballotable fluid.

Narrowing the possibilities

On the patient's second day of hospitalization (sixth day of illness), he develops petechiae on the palms and soles. A new 3- to 4-mm pustule on the dorsum of the left hand is unroofed and cultured. He complains of increased pain in the right shoulder and elbow, and range of motion is markedly compromised by pain. He also has tenderness along the clavicles bilaterally. You consult the rheumatologists, and the patient undergoes arthrocentesis of the left knee, during which 67 mL of yellow, straw-colored fluid is removed. The fluid is sent for Gram stain and culture. The cell count of the synovial fluid is 28,860 WBCs/mm³ (86% segmented neutrophils, 11% lymphocytes, 3% monocytes) and 3,774 red blood cells/mm³.

On the patient's third day in the hospital, the pain in his left knee has improved. An effusion has developed in his right elbow, and his right elbow and right shoulder are warm to touch. The right upper extremity remains exquisitely painful to passive movement. The patient has been afebrile for 24 hours and is now able to ambulate. Creatine phosphokinase and isoenzyme studies are both normal. Urinary ligase chain reaction (LCR) for Neisseria gonorrhoeae is negative.

On the patient's fourth day in the hospital, his right elbow effusion has decreased, and range of motion is improved in the right upper extremity without arthrocentesis. Results of previously ordered studies are now available: RF is 9.75 units/mL (reference range <20 units/mL), ANA is negative, ASO is 272 Todd units (normal, 0-200 Todd units), anti-DNAse B is 680 Todd units (<170 Todd units expected for school-aged children), and Lyme and RMSF serologies are negative. The mild elevation of ASO and anti-DNAse B prompt you to order an electrocardiogram and echocardiogram, which are both normal. All cultures drawn during the hospital visit have shown no growth to date, except the synovial fluid culture. On the fifth day of the patient's hospitalization, the preliminary report on the synovial fluid indicates gram-positive cocci in chains. You add parenteral clindamycin to cover possible streptococcal or staphylococcal infection.