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Q1: What does the chest radiograph in fig 2 (see p 127) show?
In addition to the diffuse interstitial pulmonary fibrosis (DIPF), there is an irregular left upper lobe opacity and apical pleural fibrosis.
Q2: Suggest two causes that would explain the new radiological finding in fig 2 (see p 127)
Pulmonary tuberculosis and lung cancer are the two most likely causes of an opacity in the upper lobe of the lung.
Q3: What three further investigations would you request?
Sputum culture for acid-fast bacilli, sputum cytology for malignant cells, and high resolution computed tomography of the chest.
Sputum culture showed mycobacterium tuberculosis that was sensitive to rifampicin, ethambutol and streptomycin, but resistant to isoniazid. Sputum cytological examination of three specimens revealed squamous cell carcinoma. High resolution computed tomography confirmed DIPF with honeycomb reticulation and ground glass opacity. A large irregular cavitating mass was apparent in the anterior segment of the left upper lobe (fig 3 below).
Q4: What is the final diagnosis and what is the relative risk of its development in patients with diffuse interstitial pulmonary fibrosis?
Lung cancer with DIPF. It is well established that the occurrence of lung cancer is greatly increased in patients with DIPF.1 2 There is an excess relative risk of 14.1 of lung cancer in patients with DIPF compared with the general population of comparable age and sex.3 The development of lung cancer in DIPF seems to be related to DIPF itself, apart from smoking and no predicting factors for its development in the presence of DIPF have been identified.3 Lung cancer in this setting occurs predominantly in males, in smokers, in the lower lobes, and in the peripheral regions of the lung.2
Q5: In your opinion, what is the major risk factor for the final diagnosis in this case?
Cigarette smoking is the most important single aetiological factor in the development of lung cancer. The patient was an elderly women who smoked heavily for more than 50 years, and had a longstanding history of DIPF. The squamous cell carcinoma she developed was in the left upper lobe and was most probably the result of her heavy smoking. Her DIPF may have been a contributory factor.
The patient was considered unfit for surgical excision or therapeutic irradiation of her neoplasm, because of her pre-existing pulmonary fibrosis. She failed to respond to a quadruple regimen of antituberculous therapy (including rifampicin, pyrazinamide, ethambutol, and ciprofloxacin; streptomycin was not prescribed because she had renal impairment during her illness). She died 3.5 months after admission. There was no necropsy.
The association of diffuse interstitial pulmonary fibrosis and lung cancer is well established
Lung cancer associated with DIPF occurs more in males, in smokers, in the lower lobes, and in the peripheral regions of the lung
Cigarette smoking acts as an additive risk factor for the development of lung cancer in patients with DIPF
Clinical and radiological screening is important in patients with DIPF
Although the association of lung cancer and DIPF is well established,3-5 little attention has been given to it. In comparison with the general population of lung cancer patients, lung cancer associated with DIPF occurs more commonly in males, and in smokers, and is predominantly located in the lower lobes and peripheral regions of the lungs.2 The precise role of DIPF as a predisposing factor for lung cancer is speculative. The fact that lung cancer occurs more frequently in the lower lobes where fibrosis is predominant supports the view that fibrosis and carcinoma are closely related. Bronchial squamous metaplasia as a precancerous state in DIPF is well recognised.2 Transition from atypical squamous metaplasia to carcinoma and anatomical correlation between sites of fibrosis and the carcinoma has been demonstrated in some instances.1
The simultaneous occurrence of lung cancer and pulmonary tuberculosis has been reported by several authors.6-10 In a review of associated lesions in patients with lung cancer,11pulmonary tuberculosis was the most frequent lesion, followed by scars, emphysema, and thickened pleura. A firm aetiological relationship between lung cancer and pulmonary tuberculosis has not, however, been established and recent analyses suggest that the association may be coincidental. When lung cancer does coexist with pulmonary tuberculosis, the diagnosis is typically delayed.7-10
Lung cancer with diffuse interstitial pulmonary fibrosis and pulmonary tuberculosis.