People suspected of having pleural mesothelioma often have some type of intervention that involves inserting a needle into the pleura. This can happen in order to obtain a tissue sample for diagnosis or to place a catheter to drain off fluid that can accumulate around the lungs. Unfortunately, mesothelioma patients who have these types of interventions are also prone to developing tiny tumors along the path where the needle was inserted.
These tumors are usually assumed to be metastatic mesothelioma that was “seeded” by the needle, and are typically treated with targeted radiation. But doctors at the University of Western Australia say clinicians should not be too quick to treat such tumors without confirming the diagnosis with a biopsy.
Dr. Ranjan Shrestha and colleagues have just published a report of two cases of mesothelioma patients who developed benign tumors at the sites of pleural punctures. In both cases, tumors developed where catheters had been placed to drain excess pleural fluid and biopsies confirmed that they were not true tract metastases.
“These cases remind clinicians that new subcutaneous lesions can be benign even when arising at pleural puncture sites of malignant pleural mesothelioma patients,” writes Dr. Shrestha. Not only did these “pseudo-tumors” not need irradiation, but they cleared up on their own without any treatment at all. Dr. Shrestha says the cases highlight the importance of performing biopsies on these types of lesions to confirm a diagnosis of mesothelioma before starting treatment.
Even when catheter site tumors do turn out to be metastatic mesothelioma, it may not be cause for alarm. Another University of Western Australia study conducted earlier this year found that these tumors typically caused only mild symptoms for mesothelioma patients and responded well to radiotherapy treatment. In that study, about 10 percent of 107 cancer patients developed metastatic cancer at indwelling catheter sites.
Shrestha, RL et al, “Pseudo-tumor mimicking indwelling pleural catheter tract metastasis in mesothelioma”, October 2014, Journal of Bronchology and Interventional Pulmonology, pp. 350-352