Pott Disease with Psoas Abscess

Clinical History

An 11-year-old boy was referred with acute paraplegia and local tenderness over the left costovertebral angle.

Imaging Findings

An 11-year-old boy was referred to our department with acute paraplegia and local tenderness over the left costovertebral angle. He had also history of left side insidious back pain, low grade fever and malaise. Chest X-ray also showed a calcified focus probably a calcified lymph node at the left hilar region however no evidence of parenchymal infiltration was found. Plain radiograph of the thoracolumbar region (not shown) disclosed destruction of the L1 vertebral body and collapse; furthermore the left psoas shadow was obscured. Helical abdominal CT was performed which disclosed left sided psoas abscesses displacing the left kidney anteriorly and involving the L1 vertebral body (Fig. 1). After obtaining the informed signed consent the psoas abscess was drained percutaneously and microbiological specimens confirmed the presence of tuberculosis. Concomitantly, medical therapy was introduced for the patient and continued for him for 4months. Six months after treatment he showd clinical improvement and CT scan shows only mild destruction of the 12th vertebra ad no residue of the psoas abscess.

Discussion

The skeleton would be involved in 3% of tuberculosis cases of which 50% involve the spine (1-3). The paradiskal lesion, which begins in the vertebral metaphysis and erodes the cartilaginous end plate, with resulting disk space narrowing and diskitis is the most common pattern of vertebral involvement in the adulthood. Abscess formation has been reported in 71%–75% of cases of tuberculous spondylitis and is seen more commonly in tuberculous infection than in cases of pyogenic infection (4, 5). The iliopsoas compartment begins at the T12 vertebra and extends to the lesser trochanter of the femur. It is in close contact with the retroperitoneal organs, pelvis, and thigh. Infections of the spine can spread into the iliopsoas compartment, pelvis, and thigh (6, 7). As shown in our case, thoracolumbar segments are the most commonly affected regions (3, 8). The disease usually is confined to one interspace, with involvement of two vertebrae, although involvement of multiple contiguous or noncontiguous vertebrae may occur (1, 3, 9-14). CT is excellent for diagnosis and radiologic evaluation in patients with iliopsoas abscesses and areas of bone destruction as well as showing needle or catheter localization, the exact location and extent of abscesses, and the relationship of abscesses to nearby organs, therefore CT can be used in all patients for percutaneous interventions.Tissue culture and histologic examination are always necessary for definitive diagnosis of tuberculous abscesses but cultures for M. tuberculosis are positive in only 50%–60% (1, 2, 15) hence, the diagnosis of tuberculosis may be presumptive and on the basis of clinical presentation features, radiographic findings, and radiologic evidence of response to antituberculous therapy in more than 50%. In some studies, negative cultures have been obtained in as many as 50%–85% of patients (16, 5, 17). As 2–8 weeks are required for the growth and identification of organisms, histologic studies showing granulomatous tissue compatible with tuberculosis and positive skin tests are sufficient to begin therapy (14, 17). In the present case diagnosis was rendered on the basis of the presence of acid-fast bacilli in the aspirate fluid. Adequate response to antituberculous chemotherapy is another recognized method of establishing the diagnosis (16-18). Conservative treatment is sufficient in 80%–98% (1, 2, 5). Failure of medical treatment, spinal deformity or instability secondary to either pathologic fracture or advanced bone destruction, worsening neurologic status, and spinal cord compression with deficit are the indications for surgery (2, 11). Percutaneous drainage (PD) has become established as the primary drainage procedure for intraabdominal abscesses, but there is limited information in the literature on PD of tuberculous psoas abscesses. Most recurrences are not due to the PD procedure but are related to inadequate antituberculous drug therapy. Drug therapy may not be efficient enough to prevent recurrence after the drainage catheter is removed as a long period of the medical treatment is necessary (5, 9, 16, 20). We believe that image-guided percutaneous drainage in conjunction with drug therapy is safe and effective in the treatment of tuberculous iliopsoas abscesses in patients with or without spondylodiskitis.

Differential Diagnosis List

Final Diagnosis

Pott Disease with Psoas Abscess

URL:	https://www.eurorad.org/case/7826
DOI:	10.1594/EURORAD/CASE.7826
ISSN:	1563-4086