Tuberculous septic arthritis of the hip with large abscess formation mimicking soft tissue tumors: A case report

BACKGROUND: Tuberculous septic arthritis is an infection that occurs inside the joint or synovial fluid and joint tissues caused by Mycobacterium tuberculosis. It may show wide variability of clinical symptoms and imaging appearance, ranging from asymptomatic with a normal radiographic examination to severe joint pain along with joint destruction, osteomyelitis, and abscess formation. This article presents radiographic and MR imaging appearance from a case of tuberculous septic arthritis with large abscess formation mimicking soft tissue tumor. CASE PRESENTATION: We reported a 32-year-old female with a slowly enlarging lump on her right proximal thigh within the last 4 months along with slowly progressing joint pain. Both radiographic and MR images showed destruction of the femoral head and acetabular roof, with a formation of large rim-enhanced abscess that extending superficially and distally until mid-thigh. The patient underwent open drainage surgery and excisional biopsy. Histopathological examination showed chronic granulomatous inflammation caused by tuberculous infection. CONCLUSION: MR imaging combined with radiographic and clinical information played a very important role in the diagnosis of tuberculous septic arthritis with abscess, and to differentiate it from soft tissue neoplasms.