How is LAM diagnosed?

Many symptoms of LAM are similar to those of more common lung diseases such as asthma and for this reason women may have symptoms for some time before LAM is diagnosed. Symptoms, X-rays and breathing (lung function) tests may suggest LAM but the diagnosis is usually confirmed by a CT scan (a detailed X-ray scan) of the lungs and sometimes with a lung biopsy. In a woman with LAM the CT scan usually shows typical cysts throughout the lungs. In around one third of cases a lung biopsy may be performed to ensure that the diagnosis is correct. This is usually carried out through a fairly small incision in the chest under a general anaesthetic. In LAM the biopsy will show the typical cysts and LAM cells. The kidney tumours are also seen best on a CT scan although they can also be seen with ultrasound. If a patient has kidney tumours or tuberous sclerosis in addition to the characteristic changes on the lung CT scan a diagnosis of LAM can usually be made without the need for a lung biopsy. Recently a raised blood level of a LAM-related protein, called VEGF-D, has also been used as a diagnostic pointer for LAM. All of these features should therefore be looked for before deciding to perform a lung biopsy.