SJ Denniston, S Rao
Respiratory Department, Birmingham Children’s Hospital.
Corresponding author: Dr Satish Rao, Consultant Respiratory Paediatrician, Birmingham Children’s Hospital, Steelhouse Lane, Birmingham B4 6NH
Email:
Satish.Rao@bch.nhs.uk
SMJ 2009 54(3): 58
There has been an increase in the incidence of tuberculosis (TB) in the United Kingdom with a rate of 14.7/100,000/year in the general population and up to 377/100,000/year in the black-african population.1 With the twin challenges of HIV associated disease and the emergence of multi-drug resistance it is imperative that we recognise and treat TB early. However, prompt diagnosis can be difficult: particularly if the patient presents with signs and symptoms of extra-pulmonary tuberculosis which are often non-specific and therefore require a high index of clinical suspicion. We report one such unusual presentation of tuberculosis.
Key Words: Tuberculosis, Infectious disease
Case Report
A 15 year old boy presented to the emergency department with a short history of a soft, non-painful boggy swelling over the left parieto-occipital region. He was a Somalian refugee who had arrived in the UK 3 years previously. He had a history of a right sided stag-horn calculus which had been successfully treated by lithotripsy.
He had no history of trauma, and there were no signs or symptoms apart from unexplained weight loss for the preceding 5 months. Neuromuscular examination was normal. Computerised tomography (CT) of the brain (Image 1 and 1a) showed partial destruction of the left parietal bone with overlying soft tissue swelling, extending into the cranium without midline shift. Four weeks later he had developed new symptoms of loss of appetite, productive cough and night sweats. Further magnetic resonance imaging of the brain (MRI) revealed that the intracranial extension of the abscess was limited to the extradural space, and oedema of the surrounding cortex was noted. A diagnosis of calvarial tuberculosis with possible cerebral involvement was made. Chest X-ray (Image 2) showed patchy consolidation bilaterally with early cavitation in the right upper lobe. Sputum showed acid-fast bacilli on ZN stain and his Mantoux test was strongly positive with an induration of 18 millimeters. The patient was treated with oral prednisolone (1mg/kg) for 4 weeks in addition to four anti-tuberculous drugs (rifampicin, pyrazinamide, ethambutol and isoniazid) as per NICE guidelines 2006. He underwent drainage of the subgaleal and extradural collection and debridement of necrotic parietal bone – histology was supportive of tuberculosis and culture was positive for mycobacterium tuberculosis, sensitive to isoniazid and rifampicin. After 12 months of treatment he has been discharged: asymptomatic and with a normal chest X-ray.
Image
1, 1a: Computerised tomogram of boggy scalp swelling
Image
2: Plain radiograph of chest
Comment
Calvarial tuberculosis was first reported in the 19th century and an incidence of 1% of bony TB was established by Strauss.2 The incidence appears to be waning – probably due to earlier diagnosis and the use of antituberculous therapy. 70-90% of cases are under 20 years, with 50% under 10 years.2 The pathogenesis is uncertain: some suggest lymphatic spread, thus explaining the rarity of the entity; while others suggest haematogenous spread which supports the apparent association with mild trauma.3 Calvarial TB usually presents with a soft, fluctuant, non-tender mass over frontal or parietal bones, and is usually associated with systemic or pulmonary disease. The diagnosis is made by clinical features, and evidence of tuberculosis on smear or culture, histology, and tuberculin skin testing. Imaging in the form of CT is useful in clarifying the extent of the lesion, and in demonstrating intracerebral or meningeal involvement. Meningitis is uncommon (4-5%) and CNS involvement of any kind is approximately 10%.2,3 Management is primarily by antituberculous drug therapy and the NICE guidelines4 would suggest 6 months is adequate: however there is lack of clear evidence and historically treatment has been for 9 – 24 months duration.3,5 Surgery is indicated if the subdural collection is resulting in an intracranial mass effect, in the presence of neurological deficit, a sinus or significant secondary infection.6 The prognosis of calvarial tuberculosis is good.
In
view of the proximity of disease to the CNS we decided to treat as if CNS
disease was present despite the lack of evidence on imaging.
A lumbar puncture was not performed as the decision to treat had been
conclusively made. 12 months antituberculous therapy is recommended for CNS
disease, as is 2 to 4 weeks of adjuvant corticosteroid4 for all forms
of TB meningitis as use has been shown to reduce mortality, although the benefit
in CNS tuberculoma is less clear.7
It is unlikely that the renal pathology was caused by tuberculosis as renal TB is usually seen late in disease, presenting most commonly in the fourth and fifth decades. It uncommonly causes renal calculi.
Conclusion
Tuberculosis
is becoming more prevalent in the UK, especially amongst recent immigrants and
ethnic minority populations. This case highlights one of the many different
presentations of tuberculosis and reiterates that tuberculosis is an important
differential diagnosis in patients presenting with non-specific clinical signs
and symptoms.
References
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Imaging
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Dexamethasone for the treatment of tuberculous meningitis in adolescents and adults. Thwaites GE, Nguyen DB, Nguyen HD et al. N Engl J Med 2004;351(17):1741-51