A Rare Case of Tuberculosis Psoas Abscess

Tuberculosis (TB) is a common infectious disease, caused by various strains of mycobacteria, usually Mycobacterium tuberculosis in human. Vertebral TB (pott’s disease) is the most common form of skeletal TB which may give rise to psaoas abscess because of close vicinity. We present a case of a woman who presented to our university hospital with a history of acute on chronic back pain and chronic fatigue. She was subsequently diagnosed with tuberculosis spondylitis (Pott’s disease) and Psoas abscess. Surgical drainage with adjuvant anti-tuberculosis therapy was carried out.


INTRODUCTION
Spinal tuberculosis (Pott's disease) is the most common form of skeletal tuberculosis.Infection begins in the antero-inferior aspect of the vertebral body with destruction of the intervertebral disc and adjacent vertebrae.The resulting anterior wedging and angulation of adjacent vertebral bodies with disc space obliteration are responsible for the palpable spinal prominence (gibbus) and a classic radiographic appearance (1).Paraspinal and psoas abscesses can develop with, extensions to the surface or adjacent tissues (2).Psoas abscess due to tuberculosis is not a very common affection for it shows a nonspecific symptomatology and therefore, it is associated to late diagnosis (3).The aim of this report is to detail our experience of the difficulties in diagnosing Psoas abscess secondary to Pott's disease, especially in the absence of other specific clinical signs.

CASE
A 40-year-old woman with complains of fatigue, low back pain for 2 years presented our university hospital.The patient reported a 2-year history of progressive back pain localized to the lower back around the waist line, which was unimproved with leaning forward.The patient reported intermittent numbness and tingling along her right leg extending laterally to the thigh and knee, which was noted to be worsen in the morning.She had subjective weakness in both legs but denied changes in urinary or bowel habits.Ibuprofen partially relieved the back pain.As interesting back ground, she has been investigated in different hospitals with the same complaints in two years and ordered abdomen computed tomography (CT) however definite diagnosis was not made.In her physical examination, She had painful abdomen at palpation at the right iliac fossa.During her follow-up, the patient was investigated for the etiology.Ultrasound of the abdomen demonstrated a hypoechoic mass suggestive of psoas abscess.Computed tomography of abdomen revealed a hypodense lesion of the right psoas muscle suggesting abscess with muscular edema and lytic lesions at S1 and S2 vertebral bodies (Figure 1) .A needle biopsy of S1 was performed, and pathology revealed necrotizing granulomatous inflammation.Biopsy specimen was sent for polymerase chain reaction (PCR) for M. tuberculosis, the result for M. Tuberculosis was positive subsequently surgical drainage of the abscess with a great quantity of pus and necrotic tissue was performed and the patient was placed on pharmological therapy (isoniazid, rifampin, pyrazinamide, and ethambutol).At the moment, The patient is in the third month the treatment and she is in a very good condition after surgery without symptoms, undergoing anti-tuberculosis treatment

DISCUSSION
Tuberculosis has been reported in all bones of the body (3,4).Bone and joint involvement account for 35% of cases of extrapulmonary disease, with the spine being the most common (4) and is by definition considered "advanced disease," requiring meticulous assessment and aggressive systemic therapy (5).The exudate formed at lumbar vertebrae most commonly enters the psoas sheath.This manifests radiologically as a psoas abscess or clinically as a palpable abscess in the iliac fossa.The typical clinical presentation of a patient with psoas abscess is a complaint of back pain, associated with fever, chills, weight loss, malaise, and fatigue (6)(7)(8).
Computed tomography is of great value in the delineation of encroachment of the spinal canal by posterior extension of inflammatory tissue, bone, or disk material (9).It is useful in assessing bone destruction, in the guidance of biopsies, and in the planning of operative procedures (4).Magnetic resonance imaging (MRI) offers excellent visualization of the bone and soft tissue components of spinal tuberculosis and psoas abscess.It can differentiate compression of the spinal cord caused by granulation material or solid material such as bone or disk (4) and is often used to identify disease at distant asymptomatic sites (9).However, as with plain films, there are no pathognomonic findings on MRI or CT that reliably differentiate tuberculosis from other infections or malignancies (10).PCR analysis was first reported as a useful technique to detect M. tuberculosis in clinical specimens in 1989 by Brisson-Noel et al. from the Pasteur Institute (11).PCR is rapid and reliable test, and the results are available within 6.5 hours, even for contaminated specimens, with reasonable sensitivity (76.4%) and excellent specificity (99.8%) (12).Tissue and body fluid specimens have not been validated as reliable in large case series (13,14).Fine needle aspiration provides a simple and safe outpatient procedure for the diagnosis of osseous TB can reduce the number of surgery (15).The treatment of tuberculous psoas abscess is based on the drainage of the abscess, either percurtaneously or surgically, in combination with specific antimicrobial therapy.Bacteriological and histopathological studies of the necrotic content of the Psoas abscess must always be performed.In most cases, evolution is favorable when the treatment is conducted correctly (16).
In conclusion, tuberculosis is still common in our country.The diagnosis of pott's disease should be considered in patients who live in endemic tuberculosis regions have chronic back pain.Microscopy and culture are recommended to confirm the diagnosis.Antimicrobial therapy, usually in multidrug combinations, is the primary spinal TB treatment; however, adjuvant surgical treatment may be warranted in cases of neurologic involvement or medical treatment failure.