How deep a superficial gravity abscess?

Abstract

A 32-year-old man with a history of alcoholic liver disease presented with progressive left-sided back pain over the previous 6 weeks. Palpable soft tissue masses over leftsided groin and back were noted 2 weeks before admission. On physical examination, he appeared malnourished and looked ill. The chest was clear to auscultation and no adenopathy was found. Examination of the lumbar and left inguinal regions showed two fluctuant, warm, mildly tender masses, measuring 6 cm  4 cm and 8 cm  8 cm, respectively, (Fig. 1). An ultrasound-guided needle aspiration was carried out. Grossly, the aspired fluid was purulent. Gram's stain showed many polymorphonuclear cells without bacteria and Ziehl-Nielsen stain showed no acid-fast bacilli. Computed tomography (CT) of the abdomen showed two loculated fluid-density masses along the left posas muscle, extending anteriorly and inferiorly to the inguinal region and posteriorly to the subcutaneous lumbar paravertebral tissues (Fig. 2a,b). The L4 vertebral body was also destroyed. A communicating tract between the two abscess-like masses was clearly shown by oblique coronal plane reconstruction of the CT images (Fig. 2c). Although the tuberculosis culture was pending, polymerase chain reaction confirmed the presence of Mycobacterium tuberculosis infection. He was treated with a combination of isoniazid, rifampicin and pyrazinamide and operative drainage was carried out for the pelvic abscess. Abscess cultures were eventually positive for M. tuberculosis, sensitive to all drugs, 2 months later.Tuberculous psoas abscess is usually found in association with tuberculous spondylitis (Pott's disease). 1 Once, M. tuberculosis was the predominant pathogen of psoas abscess, but it is now a rare entity. 2,3 The abscess may track in a variety of directions, leading to its presentation as a superficial mass palpable over the iliac crest, in the buttock or along the upper thigh after emerging from beneath the inguinal ligament, hence termed a gravity abscess. 4 In a patient presenting with a gravity abscess, the concomitant destruction of a vertebral body and presence of an adjacent psoas abscess should raise the concern of tuberculous spondylitis, particularly in immunosuppressed patients. Figure 1 Examination of the left inguinal (a) and lumbar (b) regions showed two fluctuant, warm, mildly tender masses, measuring 6 cm  4 cm and 8 cm  8 cm, respectively (asterisks).Figure 2 (a and b) Computed tomography (CT) of the abdomen showed two loculated fluid-density masses along the left posas muscle, extending anteriorly and inferiorly to the inguinal region and posteriorly to the subcutaneous lumbar paravertebral tissues (asterisks).(c) A communicating tract between the two abscess-like masses was clearly shown by oblique coronal plane reconstruction of the CT images (arrow).