incidental unilateral tuberculous sacroiliitis detected by 18f-fdg pet/ct in a patient with abdominal tuberculosis.

Tuberculosis is a systemic disease which involves skeletal and articular system very rarely. osteoarticular tuberculosis commonly occurs in the vertebral column and more rarely in the sacroiliac joints. in this study, we report a 44-years-old male patient with low-grade fever, malabsorption syndrome, abdominal and pelvic ascites and low-back pain, that underwent 18f-fdg pet/ct for identifying the cause of signs and symptoms after a negative abdominal ct and negative thorax radiography. the study revealed increased tracer uptake at the peritoneal ascites and at the right sacroiliac joint in absence of bone alteration suggesting a sacroiliitis. staining of the ascitic fluid was positive for acid-fast bacilli (ziehl–neelsen) and in the subsequent abdominal paracentesis mycobacterium tuberculosis was isolated; the final diagnosis was abdominal tuberculosis with a sacroiliac joint involvement. the patient started antitubercular therapy for 6 months and the clinical conditions were resolved, in particular both back pain and ascites disappeared.