Persistent cough in a young woman

Published on 10/04/2015 by admin

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Last modified 10/04/2015

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Problem 32 Persistent cough in a young woman

You question the patient further. Five years ago she spent 2 years as a volunteer teacher in Malawi. When she returned she underwent TB screening and had a ‘positive’ tuberculin skin test and a normal chest X-ray. At the time, the clinic placed her on a 6-month course of isoniazid preventive therapy, which she had apparently completed.

You arrange a chest X-ray. The PA and lateral views are shown in Figures 32.1 and 32.2.

Your suspicions have been aroused, and you admit her to an isolation ward for investigation and treatment. Later, your lunch is interrupted by a call from the microbiology laboratory advising that the smear from her sputum is heavily positive for acid-fast bacilli (AFBs).

Answers

A.1 A careful history in a patient with persistent cough and haemoptysis may provide clues about a possible diagnosis before any definitive investigations are undertaken.

Causes include:

This patient’s fever and night sweats strongly imply an infective cause. The more chronic nature of her history suggests that tuberculosis must be excluded. Disease caused by a non-tuberculous mycobacterium can present a similar clinical picture to TB but in this instance is considered less likely to be the causative agent. Lung abscess or malignancy would also seem less likely. You need to specifically enquire about any TB risk factors:

A.2 The chest X-ray shows a cavitating lesion in the left upper lobe, with some air space opacity in slightly contracted upper lobes.

These chest X-ray findings are highly suspicious of post-primary TB disease, especially in this clinical context. However, no chest X-ray pattern is absolutely diagnostic. Lung malignancies need to be considered and may also co-exist.

TB disease that follows primary infection can produce lower zone infiltrates, hilar or mediastinal lymph node enlargement or pleural effusions. More varied and less specific features can be seen in up to a third of cases, particularly the elderly and immunosuppressed. This can include those of primary disease, a miliary pattern, solitary or multiple nodules or even ‘normal’ chest films. Remember, TB is the ‘great mimicker’.

The radiological changes seen so far are highly suspicious of pulmonary tuberculosis and a CT scan is unlikely to provide any more definitive information. The CT scan is more sensitive than the standard chest X-ray in the examination of the lung parenchyma, mediastinum and pleura. It may be useful in those patients with less obvious or atypical features, or suspicion of other diagnoses such as cancer.

A.3