A seven-year-old boy presented to the emergency department with right hip pain, lameness and fever.
The symptoms had begun abruptly seven days before.
The second day of the disease was evaluated in an Traumatology Service and diagnosed with "hip synovitis", prescribing rest and analgesics.
The mother reported that during the following days the pain persisted at rest, awakened at night and improved without disappearance with analgesia.
She presented painful postures, functional impotence and lameness at all times.
During the seven days fever persisted (maximum 38.5 oC), accompanied by decreased appetite.
In the last days two skin lesions appeared, one in the glue and another in the scalp.
In the general inspection we found a child with wheels in regular general condition, pale and in an analgesic position with full flexion of the right hip and knee.
During the physical examination, the absence of swelling, pain or limitation at any joint level was surprising, and no painful bone points were found.
Active hip mobilization was reduced, while passive mobilization was normal.
Walking was very cautious, and standing did not support weight on the right side.
The patient was also afflicted with pedaling and a nodular, inflamed lesion, both on the scalp.
Blood tests showed mild neutrophilia and increased acute phase reactants: fibrinogen 1008 mg/dl, C-reactive protein 173 mg/l and erythrocyte sedimentation rate 100 mm/hour.
Ultrasound of the hip and radiographs of the abdomen and pelvis were normal, except for the position of pain in the latter.
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During her stay in the emergency room and after intravenous analgesia, she progressively developed abdominal pain with deep fixation in the hypogastrium and right iliac fossa without defense or other signs of peritoneal irritation.
Abdominal ultrasound was normal and acute surgical pathology was ruled out.
The fever study was completed unexplained with a chest X-ray and a urine reactive strip, which were negative, and it was decided to admit the patient to the Infectious Diseases Unit.
The Pediatric Rheumatology Department was consulted, which recommended the performance of a bone scintigraphy, which was performed in the following days, with negative results.
She was admitted with intravenous amoxicillin-clavulanic acid.
Given the normality of the tests performed and the clinical suspicion of psoas abscess, an abdominal magnetic resonance imaging (MRI) was requested, which showed an abscess in the right psoas muscle and an osteomyelitis of the vertebral body L4.
The hemocultive was sterile, but in the puncture of the scalp abscess, Staphylococcus aureus resistant to open was covered by line, which was modified to antibiotics for this germenzolid,
The patient was admitted favorably with no need for surgical drainage.
