An 18-year-old girl presents with nighttime fevers to 39°C for 8 days. She complains also of headache, myalgia, and rash during the fevers. Eighteen days ago, she removed a tick from her neck after attending a festival in the northeastern United States. One week ago, she presented to her pediatrician with a sore throat and rash. She was hyponatremic (sodium, 129 mEq/dL) and was started on doxycycline for presumed Rocky Mountain spotted fever (RMSF). Her condition has not improved. She admits to multiple unprotected sexual encounters and cocaine abuse. The girl appears weak. Her vital signs include temperature of 38.7°C; heart rate, 84 beats per minute; respiratory rate, 20 breaths per minute; and blood pressure, 113/73 mm Hg. A salmon-colored macular rash is present on her trunk and proximal extremities. She also exhibits dermatographia. There are no mucosal lesions. The liver is enlarged to 2.5 cm beyond the rib margin, and she has right upper quadrant tenderness. Her muscles are tender to deep palpation in all four extremities. She is able to bear weight but refuses to ambulate due to bilateral lower extremity myalgia and arthralgia. A CBC demonstrates a normochromic, normocytic anemia, and leukocytosis with a left shift. ESR and CRP are elevated at 109 mm/hour and 19.8 mg/dL, respectively. A mild transaminitis is present. Ultrasonography reveals a mildly enlarged and echogenic liver. Small pleural and pelvic effusions are present on CT scan. A bone marrow biopsy and a glycosylated ferritin fraction are obtained. A clinical diagnosis is made. An 11-year old Hispanic boy who had poststreptococcal reactive arthritis (PSRA) and rheumatic fever (RF) diagnosed at age 6 years has been symptom-free while taking oral penicillin (PCN). Two months ago, he developed lemon-sized, reddish, painful subcutaneous nodules that were warm to touch on both lower extremities and revealed acute …