Tubercular spondylitis with prevertebral and epidural abscess masquerading as a mediastinal mass

Case report

A 10-year old girl presented with an insidious-onset low-grade fever for one month. She had had an episode of sudden-onset choking sensation while eating, followed by breathlessness and palpitations one day before presentation. There was no history of weight loss, night sweats, cough, dysphagia, nor bony pains. A significant family history of tuberculosis (TB) in a paternal uncle was discovered. On examination, our patient's throat was normal. She had tenderness in the upper thoracic spine with a normal neurological examination, and no other significant external signs.

Investigations including full blood count, renal and liver function were normal. C-reactive protein was elevated (105.6 mg/L). A chest radiograph revealed mediastinal widening with bilateral peri-hilar opacities (Fig. 1(a)). MRI spine scan revealed dorsal spondylitis with collapse of T2-4 vertebral bodies and erosion of anterior and posterior plates of T1 with evidence of L1 and L3 spondylitis. Pre-vertebral and epidural collections of 3 × 6.5 × 8 cm were seen, pushing the mediastinal contents anteriorly and laterally (Fig. 1(b) to (e)).

OPEN IN VIEWER

Figure 1.

Tubercular spondylitis with pre-vertebral and epidural abscess. (a)–(e) Chest radiograph (a) showing mediastinal widening. MRI sagittal (b, c) and coronal (d, e) views showing thoracic prevertebral collection (yellow arrows) and vertebral changes.

Beta human chorionic gonadotropin and alpha fetoprotein levels were normal. Gastric lavage was negative for acid-fast bacilli. A pus sample was retrieved with CT guidance; cartridge-based nucleic acid amplification test (CBNAAT) was positive for rifampicin-sensitive Mycobacterium tuberculosis. Anti-tubercular therapy (ATT) was therefore initiated and a lower back brace supplied. At two-month follow-up, our patient was gaining weight and improving symptomatically.

Discussion

The predominant forms of extrapulmonary TB involve the meninges, the abdomen and spine. In endemic regions, spinal TB is more common in children compared to adults. ¹ It results from haematogenous spread. ¹ Intra-osseous venous systems contribute to spread of infection, including non=contiguous vertebral spread. ¹ In the initial stages, spinal TB involves the anterior inferior portion of the vertebral body, followed by the central part and the disc in later stages. ¹ A radiograph is less sensitive in the early stages, as it does not reveal any abnormality until about ¹/₃ of calcium loss occurs.^1,2

Then typical findings are reduced bone density, end-plate erosions, loss of disc space, destruction and sequestration of bone, decreased vertebral height, collapse and cold abscesses seen as paravertebral soft tissue densities,^1,2 with characteristic calcification. ² MRI is more sensitive, ¹ revealing marrow oedema, disc destruction, collapse of vertebral bodies, and pre-vertebral, para-vertebral and epidural abscesses.^1,2 Tuberculous spondylitis with abscess presenting as a mediastinal mass is rarely reported in adults and even more rarely among children.^3–5 Significant improvement in symptoms was found on ATT, so the search is worthwhile in endemic countries.