Secondary lung tumours
Metastases to the lung are very common due to haematogenous spread.
The site of primary is usually the kidney, prostate, breast, bone, gastrointestinal tract, cervix or ovary.
Secondary tumours nearly always develop in the lung parenchyma where they cause little or no symptoms. Carcinoma, particularly of the stomach, pancreas or breast can spread via the pulmonary lymphatic vessels causing a syndrome of lymphangitis carcinomatosa.
Usually asymptomatic, it is usually found as part of the screening of a patient with known malignancy. Rarely cause chest pain, haemoptysis or breathlessness (the last suggests lymphangitis carcinomatosa).
Identification is by chest X-ray usually appearing as round shadow(s) 1.5–3 cm in diameter. CT scan shows up smaller metastases in most cases. Renal tumour metastases may present as a solitary round shadow. In lymphangitis carcinomatosa there is characteristically bilateral lymphadenopathy with dilated intrapulmonary lymphatic vessels appearing as streaky shadowing over both lung fields emanating from the hilar regions.
Truly single metastases can be removed surgically, but this is uncommon.
Lymphangitis carcinomatosa is rapidly fatal.