The Great Masquerader: Tuberculous Spondylitis Another Differential Diagnosis in Back Pain By Clement Jones, MD
Pott's disease has been coined the great mimicker and should always be considered in the differential diagnosis of spine pain. A New York Times article in January, 1988 reported a "substantial increase in tuberculosis in the United States for 1986" which was attributed, at least partially, to acquired immunodeficiency syndrome (AIDS). For several decades, the incidence of tuberculosis had decreased dramatically and (especially in developed Western Countries), had become essentially uncommon. In 1980, large number of infected refugees immigrated from Southeast Asia. Along the West Coast of the United States the growing percentage of the population continues to arrive from the Western Pacific rim nations where the incidence of tuberculous spondylitis remains common. AIDS patients, Asian immigrants, and natives of other endemic regions, intravenous drug abusers, and other patients with suppressed immune systems may be susceptible to pyogenic or vertebral osteomyelitis, or discitis.
Case Report:
T.J. is a 32-year old woman from the Philippine islands who presented with a two year history of right sided lower back pain. She denied any buttock or lower extremity radiation. Her pain was insidious in onset, intermittent in nature, and gradually progressive in intensity. She denied noting any lower extremity weakness or paresthesias, or meningeal irritation signs, or systemic symptoms including fever, chills, night sweats, or weight loss. Her examination was only remarkable for a large, firm, tender, 10 x 20 cm., right iliolumbar retroperitoneal mass extending to the right lower quadrant. Plain radiographs from 21 months earlier revealed a questionable lytic area in the superior half of the L2 vertebral body. A gynecologic examination and pelvic ultrasound confirmed a cystic retroperitoneal mass. CT scan revealed a large right psoas abscess and a lytic lesion in the right superolateral portion of the L2 vertebral body, narrowing of the L1-2 disc space, a lytic lesion at the right anteroinferior corner of L1, and, slight right lateral tilting of L2 with mild L1-2 foraminal narrowing. CT-guided drainage tubes were passed into the right psoas abscess with serial CT scans revealing progressive drainage and diminution in abscess size. Her medical regimen include Myambutol, Pyrazinamide, isoniazid and rifampin. She was placed in a molded polypropylene body jacket with 15° thoracolumbar extension.
Overview:
Tuberculous spondylitis can have myriad, variable clinical presentations. Classically, the typical complaint is spine pain and manifestations of chronic illness including weight loss, malaise, fever, and/or night sweats. Examination may demonstrate deformity (kyphus), local tenderness, muscle spasm, restricted motion, a mass in the groin, thigh or flank, or, neurologic deficit. Erythrocyte sedimentation rate is generally elevated, but is usually nonspecific. Tuberculin purified protein derivative (PPD) skin test is usually positive and indicates only a history of exposure (remote or current). Early morning urine sample cultures may be positive if there is renal involvement. Sputum specimens are positive only if there is active pulmonary disease. The only laboratory finding which can absolutely confirm the diagnosis is a positive culture from a spinal lesion biopsy (cut out). complete destruction on either side of the disc, central vertebral body destruction, anterior scalloping, osteopenia, kyphosis, paravertebral abscess, and, (cut out).
Computed tomographic (CT) scan will delineate the extent of bony destruction as well as soft tissue changes around the spine and in the canal. Magnetic resonance imaging (MRI) is the imaging modality of choice because it will demonstrate bony and soft tissue involvement, and, can distinguish tuberculous vs. pyogenic etiology. Radionuclide scanning with technetium or gallium are not as helpful due to low sensitivities. The false-negative rates for technetium bone scans and gallium scans are 35 and 70%, respectively. The goals of treatment are to eradicate infection, and, prevent or treat neurological deficits and spinal deformity. Four years ago the Medical Research Council Committee for research for tuberculosis in the Tropics concluded the treatment of choice for spinal tuberculosis in developing countries is ambulatory chemotherapy for 6 or 9 months with isoniazid and rifampin. Surgery is reserved for biopsy, management of myelopathy, abscesses and sinuses, and intuitively, for stabilization to prevent or correct kyphotic deformity especially if there is an associated and progressive neurologic deficit.
Conclusion:
The case report example above illustrates the importance of considering tuberculosis (or other granulomatous spondylitis) in the differential diagnosis of back pain. Careful history taking and physical examination, and scrutinous review of plain radiographs will usually lead one to the correct and early diagnosis.
References
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9. Yau, et al: Tuberculous kyphosis. Correction with spinal osteotomy, halo pelvic distraction and anterior and posterior fusion. Journal of Bone and Joint Surgery 56A:1419-1434, 1974
