You are asked to review a chest X-ray for a colleague. You notice a round opacity which of the following is NOT one of your differential diagnoses?

d. There are many causes of round opacities on chest X-rays. Their location may provide a clue to the likely diagnosis but often it is necessary to revert back to the history and examination for clues. Tuberculosis tends to present in the apices due to the apparent improved oxygenation. Both lung cancer and carcinoid tumour can present anywhere in the lung fields as round lesions.

Sarcoid is a multi-system disorder characterised by noncaseating epithelioid granulomas. Other commonly involved organ systems include the lymph nodes; the skin; the eyes; the liver; the heart; and the nervous, musculoskeletal, renal and endocrine systems. Patients usually complain of non-specific symptoms including weight loss and fatigue. Chest symptoms are fairly common amongst sufferers of the disease.