The chest x-ray exhibits a well circumscribed opacity in the left upper lobe with ‘popcorn’ calcification. This is a feature of pulmonary hamartoma, which is a benign neoplasm of the lung.

When faced with an unusual finding on a chest x-ray, always try to get hold of older images to compare. For this patient, examination of previous chest x-rays indicated a persistent presence of the hamartoma, thereby suggesting a benign feature.