Description

A teenage male, without a significant medical history, was admitted to our hospital with a 4-day history of fever, left lower abdominal, left leg and groin pain, and malaise. He was a high-school soccer club member who practised rigorously, but he denied any history of recent skin infection, major traumatic events in the pelvis, abrasions or intravenous drug use. On examination, his vital signs were unremarkable, other than a body temperature of 39.6℃. He had marked tenderness over the left lower quadrant of the abdomen, and active and passive movement exacerbated the pain in the left leg, especially in the left groin area without radiation. He did not have any murmurs, splinter haemorrhage, Osler nodes or Janeway lesions. Laboratory tests revealed a C reactive protein level of 88.2 mg/L without leucocytosis. CT and MRI examinations were performed after admission (figures 1 and 2). MRI findings showed a T1 low-signal intensity lesion and T2 high-signal intensity lesion in the left pubis and the blood culture yielded methicillin-sensitive Staphylococcus aureus. Transthoracic echocardiography did not observe any signs of vegetation or abscess, and follow-up blood culture was sterile at 2 days after starting antibiotic administration. These findings were consistent with the diagnosis of acute bacterial osteomyelitis. We initiated intravenous cefazolin administration for 2 weeks, followed by oral clindamycin for 4 weeks considering higher bone penetration capacity. After the antibiotic treatment, the patient fully recovered from the infection without surgery. The pelvic pain disappeared after 1 month and he denied any recurrent symptoms 1 year later.

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Figure 1

CT scan showing bony margin irregularity.

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Figure 2

MRI: T1 scan (A) of low-signal intensity and T2 scan (B) of a high-signal intensity lesion in the left pubis.

This case highlights that we should consider several differential diagnoses involving musculoskeletal-related, hip-related and other aetiologies in athletes complaining of groin pain.1 Osteitis pubis, a non-infectious chronic inflammatory condition without systemic inflammation, is particularly common in athletes who are involved in leg twisting sports.2–4 Its incidence is relatively high; that of osteitis pubis is approximately 0.5%–8% in athletes, and male soccer players could be vulnerable to injuries (annual incidence, 10%–18%).4 Additionally, approximately 76% of radiological abnormalities are detected in professional soccer players.5 However, acute bacterial osteomyelitis in the pubis is rare (<1% of all haematogenous osteomyelitis) but is another essential differential diagnosis as in this case.6 7 Pre-existing trauma or minor injury in the pubic area is considered a possible predisposing factor in athletes, and the haematogenous seeding of transient bacteraemia resulted in pubis osteomyelitis.6 S. aureus is the predominant causative pathogen in athletes because it could be related to the localised infection due to bacteraemia.6–8 On the other hand, causative pathogens could be polymicrobial in postoperative cases or patients with pelvic malignancies.7 8 The presentation and radiological abnormalities are similar to those of osteitis pubis, which may lead to a diagnostic error. Hence, clinicians should be aware of the infection, and a blood culture or bone biopsy is warranted to distinguish between osteomyelitis and osteitis pubis, particularly in athletes complaining of pelvic pain.9