Bilateral iliopsoas abscess is an uncommon presentation of Pott’s spine. We recently cared for a young, immunocompetent male who presented with a right paravertebral swelling. He had been on antitubercular therapy (ATT) for 6 months for pulmonary tuberculosis. On computerized tomography (CT), the patient was found to have Pott’s spine as the primary pathology with extensive iliopsoas abscesses bilaterally. The aspirate from the swelling grew Mycobacterium tuberculosis, which was resistant to isoniazid and rifampicin. He was then started on appropriate drugs according to sensitivity reports. Our patient was a rare case of a young, immunocompetent male who presented with large bilateral psoas involvement due to Pott’s spine. This was not associated with any neurological deficit. The organisms were multidrug-resistant, even though the pulmonary lesions had resolved after being on ATT for 6 months. To conclude, for any tubercular patient presenting with paravertebral abscess or back pain, Pott’s spine should be considered among the differential diagnoses, especially in endemic regions. Tubercular culture and sensitivity should be done in all such cases due to the widespread prevalence of drug-resistant forms.
Keywords: Drug-resistant tuberculosis, Pott′s spine, tuberculosis
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Sharma K, Suhani, Ali S, Aggarwal L, Thomas S. Bilateral extensive tubercular iliopsoas abscess: An uncommon manifestation of Pott’s spine. Ann Trop Med Public Health 2015;8:10-2
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Sharma K, Suhani, Ali S, Aggarwal L, Thomas S. Bilateral extensive tubercular iliopsoas abscess: An uncommon manifestation of Pott’s spine. Ann Trop Med Public Health [serial online] 2015 [cited 2021 Jan 26];8:10-2. Available from: https://www.atmph.org/text.asp?2015/8/1/10/156705
Tuberculosis is a pandemic and among the top 10 killer infectious diseases, second only to human immunodeficiency virus (HIV), with 9.4 million cases reported worldwide. , Only 1-2% cases show the involvement of the skeletal system, among which tubercular spine (Pott’s spine) constitutes almost half of the cases.  Patients with Pott’s spine commonly present with local pain, constitutional symptoms, or paraplegia due to cord compression.  The condition may be complicated by the development of psoas and/or retroperitoneal abscess, with or without neurological sequelae.  However, most cases are unilateral, with bilateral disease being noted in only 3% of cases.  We report a case of extensive bilateral iliopsoas abscess resulting from Pott’s spine in a young male presenting with a right paravertebral cold abscess.
A 28-year-old male presented with swelling over the right paravertebral region for the past 20 days. It was not associated with pain, fever, or trauma. He was a known case of sputum-negative pulmonary tuberculosis on antitubercular therapy (ATT) for the past 6 months. There was a history of low back pain for 1 year without any gait abnormalities or neurological symptoms. On examination, there was a swelling approximately 8 × 8 cm in the right paravertebral area in the lumbosacral region [Figure 1]. It was fluctuant without any signs of acute inflammation. No spinal tenderness or neurological deficit of the lower limbs was present. The rest of the examination was unremarkable. The patient was further investigated, with a provisional diagnosis of a paravertebral cold abscess. Spine radiography was normal, except for a prominent right psoas shadow. Ultrasonography of the abdomen depicted bilateral psoas abscess with thick necrotic debris. The pulmonary consolidation and pleural effusion for which ATT was started had resolved on the chest radiograph. The patient then underwent contrast-enhanced computerized tomography (CECT) abdomen, which showed a thick-walled collection involving both psoas muscles and extending posteriorly till the paraspinal muscles. On the right side it was seen to extend till the quadratus lumborum, iliacus, and erector spinae muscles, and bulging in the subcutaneous region. There was loss of fat plane with the right gluteus maximus muscle [Figure 2]a and b. The abscess was seen to extend into the epidural space via the neural foramina at L4 level. It extended till L3 with displacement of the neural foramina toward the left side. Small lytic lesions were seen in the body of T12, L2, and L5 vertebrae. Abdominal viscera and bowel were normal. A diagnosis of Pott’s spine with bilateral iliopsoas abscess was made. The pus showed absolute lymphocytosis and was positive for acid-fast bacilli (AFB) staining and culture. Drug sensitivity testing showed resistance of the pus to isoniazid and rifampicin. HIV serology was nonreactive. The patient was prescribed a Taylor brace by the treating orthopedician and was started on ATT based on his culture reports. A percutaneous aspiration of the abscess was done, leading to near-resolution of the swelling.
|Figure 1: Clinical photograph of patient showing right paravertebral swelling
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|Figure 2: (a) CECT showing bilateral extensive iliopsoas abscess (b) Low-contrast resolution images showing right > left iliopsoas abscess
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Psoas abscess can be classified as either primary or secondary. The etiology of primary psoas abscess remains uncertain – it may result from either hematogenous spread from occult sites of infection or local trauma with resultant intramuscular hematoma formation, which predisposes to abscess formation.  These abscesses occur most commonly in patients with a history of diabetes, injection drug use, alcoholism, acquired immunodeficiency syndrome (AIDS), renal failure, hematologic malignancy, or malnutrition. The predominant organism is Staphylococcus aureus (over 88%), followed by Escherichia coli and Streptococcus.  Secondary psoas abscess occurs due to an identifiable cause. Mycobacterium tuberculosis infection of the spine, known as Pott’s disease, is the most frequent cause of secondary psoas abscess in developing countries.  Other conditions associated with secondary psoas abscess include Crohn’s disease, diverticulitis, appendicitis, colorectal cancer, urinary tract infection, vertebral osteomyelitis, mycotic abdominal aortic aneurysm, endocarditis, and history of instrumentation in or around the spine. Bilateral psoas abscess occurs in just 3% of all cases, primary or secondary. 
Back pain is the most frequently encountered symptom. The commonly described triad of fever, back pain, and psoas spasm is present in only 30% of patients.  Patients with symptoms of Mycobacterium tuberculosis etiology are even less likely to show classic signs and symptoms, which may delay definitive diagnosis and treatment.  This feature of a delayed presentation was also seen in our patient.
Radiographic changes associated with Pott’s disease present relatively late and include lytic destruction of the anterior portion of the vertebral body, increased anterior wedging, and enlarged psoas shadow with or without calcification. An intervertebral disc may be shrunken or destroyed, and vertebral bodies may show variable degrees of destruction. Fusiform paravertebral shadows suggest abscess formation.  Computerized tomography (CT) scanning yields much finer bony detail of the irregular lytic lesions, sclerosis, disk collapse, and disruption of bone circumference. Low-contrast resolution provides a better assessment of soft tissue, particularly in the epidural and paraspinal areas. Magnetic resonance imaging of the spine is the standard method of evaluation of disk space infection, and the most useful in demonstrating extension into the soft tissues.  Also, to note, the paradiscal type is the most common type of this disease. The disk spaces were normal on CT in our patient.
Treatment includes abscess drainage along with antituberculous medications. CT/ultrasound-guided percutaneous catheter drainage (PCD) and surgical drainage are the two definitive treatment modalities. PCD is less invasive and currently the treatment of choice.  Surgical drainage is indicated when PCD fails, if there is a contraindication to PCD or abdominal pathology that requires intervention. Spinal surgery was not indicated in this patient as it is indicated in select cases when neurological deficit does not improve with ATT. 
Our patient is a rare case, being a young, immunocompetant male who presented with a paravertebral cold abscess, which was an undiagnosed, underlying extensive bilateral iliopsoas abscess due to Pott’s spine without any neurological deficit. He harbored multidrug-resistant organisms despite resolution of the pulmonary lesions with ATT.
Psoas abscess secondary to Pott’s disease of the spine is not a rare condition, but bilateral psoas abscess with delayed presentation and extensive tissue necrosis present a rare picture. A high index of suspicion and proper imaging in a symptomatic patient may lead to early diagnosis and treatment. A percutaneous approach to draining the abscess should be the preferred modality. Culture and drug sensitivity testing of the organism should be done prior to drainage of pus in all cases not responding to the standard therapy.
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Source of Support: None, Conflict of Interest: None
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