Achy muscles: Pyomyositis/myositis

Case presentation

A previously healthy 14-year-old male presents with left lower quadrant pain, difficulty bearing weight, and fever. He awoke 6 days ago with sharp left lower quadrant pain. At that time, he was seen at an Emergency Department where abdominal computed tomography (CT) and bloodwork were obtained, which were reported to be normal. He was diagnosed with abdominal wall strain and was discharged home with ibuprofen. He reports that this medication has not helped his pain. He went to his primary care provider the following day, who diagnosed mesenteric adenitis and prescribed hydrocodone. The patient reports that the pain has persisted despite this additional medicine. Several days ago, he developed fever, which has been intermittent since then. He states that he has had progressive difficulty with ambulation secondary to pain. He returned to his primary care provider 2 days ago, who obtained plain radiography of the pelvis, which was normal by report. He has not had preceding trauma, although he states that he is a track and field runner, has an extensive exercise routine, and is unsure if he “pulled something” prior to his current symptoms. He denies vomiting, diarrhea, dysuria, or back pain.

He is febrile to 103 degrees Fahrenheit, has a pulse of 106 beats per minute, a respiratory rate of 24 breaths per minute, and a blood pressure of 109/54 mm Hg. He is not in distress but complains of left-sided hip pain, radiating to the left anterior thigh. His abdominal examination reveals tenderness to the left lower quadrant without rebound or guarding. He has exquisite pain with manipulation of his left leg, pointing to the left hip and left thigh. There is no erythema, swelling, fluctuance, or warmth, but he is tender to palpation over the left anterior thigh.

A review of the outside CT report does not mention any abnormalities. Laboratory work is obtained, revealing a total white blood cell count of 15,000 cc/mm, normal urinalysis, a C-reactive protein (CRP) level of 35 mg/dL, an erythrocyte sedimentation rate (ESR) of 90 mm/hour, and a creatine phosphokinase (CK) level of 299 units/L.

Imaging considerations