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Rare Types of Mesothelioma and How They Were Diagnosed

types of mesothelioma

There are quite a few things that are rare when it comes to types of mesothelioma.

  1. Malignant pleural mesothelioma itself is a rare disease.
  • Shoulder complaints are rare as a first symptom of malignant pleural mesothelioma, and found in about 14% of cases, according to one study.
  • As rare as it is to find mesothelioma in the pleural cavity, it’s even rarer to find it in the genital tracts, tunica vaginalis, pericardium and peritoneum.
  • Malignant mesothelioma was one of the rare types of mesothelioma prior to the widespread commercial introduction of asbestos. No cases of it were identified in 2025 autopsies that were performed between 1883 and 1910.
  • Mesothelioma is rare in younger age groups.
  • Malignant mesothelioma in the spinal canal is extremely rare.

Malignant Mesothelioma That Spread to the Spinal Canal

Usually, mesothelioma starts in the lungs. But in one patient reported in the medical literature, his mesothelioma was quite rare. It showed up in his spinal canal as a primary tumor there. Here are the details of his case:

            Patient: 35-year-old man

Initial Symptoms:  3-month history of swelling and pain in his left lower leg.

Doctor visit uncovered he didn’t feel sensation below the L5 dermatome. The doctor ordered an MRI and sure enough, a mass appeared at L4-5. Off to surgery he went and the histology report of the tumor stated he had sarcomatoid malignant mesothelioma. This is the one of the worst types of mesothelioma, as it is the most aggressive and has the worst prognosis. A CT scan of his thorax and abdomen didn’t find any additional lesions.

Treatment: The patient refused chemo and radiation. PET scans 3 months later did not show any abnormalities. However, an MRI at 8 months after the initial surgery when he developed back pain and difficulty with bowel movements showed the tumor had returned. During surgery for this, the doctors found that the tumor had spread to the vertebrae and the cauda equina. Surgery partially alleviated the patient’s pain. Two months later, the patient passed away in a traffic accident.

In this unusual case, the normal surgical resections did not work and possibly helped to spread the cancer to the vertebrae and cauda equina. The patient had a reduction of pain but still had to deal with the pain of mesothelioma up until his death.

Metastases from Mesothelioma to the Brain

In Australia at the Department of Neurosurgery in Heidelberg, Victoria, doctors reported that mesothelioma was previously considered a local disease that didn’t metastasize frequently. However, this appears to be changing.

Autopsies are now showing that metastases to the brain are occurring from malignant mesothelioma even though only a handful of cases have been reported in the medical literature.

The neurologists in Australia discussed in their journal article a case of cerebral metastasis in a patient with malignant mesothelioma and was still alive. The patient had symptoms affecting the brain but didn’t go into depth about them in their abstract. The patient had a craniotomy and two tumors were removed from the brain. A craniotomy is a brain operation where part of the skull bone is removed temporarily so that the doctors can access the brain.

Doctors at the Bethesda, Maryland branch of the National Cancer Institute reported on two cases where malignant pleural mesothelioma metastasized to the brain. Here are details of the cases:

1.  Patient 1 – 60-year-old Man

                        Diagnosis date: June 2010

Treatment: 6 chemo cycles from July to November 2010 but this didn’t work and 11 more cycles of chemo were tried. His disease continued to progress.  Then he entered a phase 1 clinical trial of the National Institutes of Health in March 2012, where he got another three cycles of chemo but was withdrawn from the study. 

In late August 2012, he had a trip to the ER because of weakness of his left arm and leg and had an MRI of the brain. That’s where they found three masses in his brain. They biopsied them and found that they were metastases and treated him with dexamethasone and whole brain radiation therapy in September 2012. The masses did not respond to the treatment. He stopped treatment, went to hospice, and died in January 2013.

            2. Patient 2 – 59-year-old Man

                        Diagnosis date: September 2008

Treatment: 3 chemo cycles in November 2008 and was referred to the National Cancer Institute in March 2009 for investigation. He didn’t have any CNS symptoms. An MRI of the brain showed one lesion. He had resection of the lesion in March 2009 and further imaging showed the lesion had been removed. However, six weeks later, another lesion appeared in another part of the brain. Doctors said it was a metastasis. Histological tests confirmed this.

In case studies from seven autopsy studies, researchers found 655 cases of malignant pleural mesothelioma. Other types of mesothelioma were not included. Of these cases, 2.7% became ones where the mesothelioma spread to the brain and/or meninges.  The clinical features vary in each case, depending on where the lesions are located. It’s less common for the metastases to involve the midbrain, pons, or brainstem.

Types of Mesothelioma of the Tunica Vaginalis Testis

Mesothelioma of the tunica vaginalis testis is extremely rare. It’s only seen in up to 0.5% of all malignant mesotheliomas and is the result of exposure to asbestos. Because it’s so rare, doctors are generally not looking for it, and it’s diagnosed by accident when someone has surgery. 

Here are the details of a case of this rare type of mesothelioma:

            40-Year-Old Male Patient

The patient was admitted to the hospital for normal surgery of a left hydrocele. The doctors discovered an unusual nodular thickening of the tunica vaginalis and had a tissue sample taken and sent to the pathology department. The results came back with diffuse malignant mesothelioma. The patient’s left scrotum and left inguinal lymph node was removed and dissected and they further found the cancer was spreading although it did not get into the testicle or lymph nodes. However, the CT scan did not find metastases. CT scans over the next six years found no evidence of cancer.

The doctors concluded that an aggressive approach of removing the scrotum with or without removal of the lymph nodes could reduce the risk of recurrence.

Doctors should periodically review rare case presentations of mesothelioma so that they don’t miss new cases. These three types of rare types of mesothelioma are here for doctors’ reviews.


Chen, F., et al. Primary spinal malignant mesothelioma: a case report and literature review. World Neurosurg 2018 Jun;114:211-216. Doi:10.1016/j.wneu.2018.03.124. Epub 2018 Mar 26.

Mah, E., Bittar, R.G., and Davis, G.A. Cerebral metastases in malignant mesothelioma: case report and literature review. J Clin Neurosci 2004 Nov;11(8):917-8.

Miller, Andrew C., et al. Malignant mesothelioma and central nervous system metastases. Report of two cases, pooled analysis, and systematic review. Ann Am Thorac Soc 2014 Sep;11(7):1075-1081.

Strauchen, J.A. Rarity of malignant mesothelioma prior to the widespread commercial introduction of asbestos: the Mount Sinai autopsy experience 1883-1910. Am J Ind Med 2011 Jun;54(6):467-9.

Trenti, E., et al. Malignant mesothelioma of tunica vaginalis testis: Report of a very rare case with review of the literature. Arch Ital Urol Androl 2018 Sep 30;90(3):212-214.

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