Diagnosis for a 60 year-old man who is referred following a Chest X ray that suggests interstitial lung disease.

A 60 year-old man is referred following a Chest X ray that suggests interstitial lung disease. You proceed to bronchoscopy with transbronchial lung biopsy to try and make a definitive histological diagnosis.
Which of the following is the least likely diagnosis to be confirmed in this way?
A. Cryptogenic fibrosing alveolitis (CFA)
B. Sarcoidosis
C. Extrinsic allergic alveolitis
D. Cryptogenic organising pneumonia (COP)
E. Lymphangitis carcinomatosa

Answer;
A) Cryptogenic fibrosing alveolitis (CFA)

Discussion;  Cryptogenic fibrosing alveolitis (CFA) can be a patchy disease and transbronchial bronchoscopy (TBBx) may simply reveal established fibrosis with no particular etiology suggested. If a biopsy is required in CFA then a surgical lung biopsy, guided by (HRCT) appearances, will give better specimens.
Sarcoidosis and Extrinsic allergic alveolitis are both suggested by granulomas, lymphangitis by malignant cells and Cryptogenic organising pneumonia (COP) by the presence of organizing pneumonia.