What is Benign Mesothelioma?

While the majority of mesothelioma diagnoses are malignant, meaning cancerous, it is possible for benign tumors to form in the mesothelium. Unlike malignant mesothelioma, these benign tumors are typically removed through surgery and do not require additional treatments. Benign tumors are not capable of metastasizing or spreading to other organ systems. However, it is important for patients to recognize the distinction, as malignant mesothelioma is a very serious, rapidly progressing cancer with a 4- to 18-month survival rate following diagnosis.

Types of Benign Mesothelioma

The American Cancer Society lists three different types of benign mesothelioma which, like malignant mesothelioma, are differentiated by their location.

  • Adenomatoid tumor—this benign tumor develops in the mesothelium of certain reproductive organs. In men, it often starts in the epididymis, which is a collection of ducts that carry sperm cells out of the testicle. In women, this tumor is likely to begin in the fallopian tubes.
  • Benign cystic mesothelioma—this tumor usually begins in the mesothelium near female reproductive organs.
  • Solitary fibrous tumor of the pleura—originally called benign fibrous mesothelioma; doctors have since discovered that this tumor starts from tissue located underneath the mesothelium cells themselves. While typically benign, the American Cancer Society notes that one in 10 cases can be cancerous.

As is the case with malignant mesothelioma, the benign variation is more likely to affect men than women. The fact that the tumor is noncancerous does not mean the patient is without symptoms or discomfort. If the tumor is able to grow before being removed, it can push on the lung or other organ, causing symptoms such as shortness of breath, chest pain, and chronic cough. Most people with benign mesothelioma are diagnosed via an imaging scan that was conducted for other reasons.