Case presentation
A 14-year-old boy was admitted to the hospital in February 2021 with a four-week history of malaise, fatigue, generalized muscular pain, night sweats, and significant weight loss, which started insidiously. He denied any history of previous illnesses. He was living in a rural area, and his father was a shepherd therefore he had regular contact with sheep. His father and his brother had a history of Brucellosis.
Three days before admission, severe pain was started in his left inguinal region leading to an abnormal gait. As to reduce the pain, he had used some analgesics, including Acetaminophen and Ibuprofen. At presentation, on physical examination, he appeared exhausted and ill. His body temperature was 37.5°c, and his pulse rate was 106 bpm. He also had an antalgic gait pattern. Tenderness on his left hip was detected. The Faber test was positive on the left side although, the internal rotation of the hip joint was intact. A painful left inguinal adenopathy was also detected.
The patient’s laboratory tests demonstrated white blood cell count of 6600/ \(\text{mm}^{3}\) (65% Neutophils, 35% Lymphocytes), hemoglobin concentration of 11.4 g/dl, platelet of 324000/mcL, ESR of 34 mm/hr and CRP of 3 mg/L. The Standard Tube Agglutination test for Brucellosis was 1/320, and the 2ME test was 1/160, which both were considered positive.
On the performed Ultrasound, the depth of the left hip joint capsule was 5.5 mm while the depth of the right hip joint capsule was 5 mm. on the left side and near the hip joint (3 mm of the joint capsule and 14mm of the skin surface) there was an echolucent area measuring 34*16*12 mm with thin septa, and the volume was almost 4 cc. According to these findings, more investigations were recommended.
On the Magnetic Resonance Imaging (MRI), there was edema and fluid collection within the left iliopsoas muscle and the left pectineus suggesting a Psoas abscess accompanied by a mild pre-capsular inflammation. However, both hip joints were normal and obvious evidence of effusion was not seen (figure 1).