Cystic Mesothelioma

Cystic mesothelioma is a very rare histological subtype, or cell type, of mesothelioma that almost exclusively develops in the peritoneum, or lining of the abdominal cavity. It is usually a benign condition, meaning non-cancerous or non-malignant. Another factor that differentiates cystic mesothelioma from other malignant mesothelioma types is that it's much more common in women than in men.

The condition is marked by cysts and lesions that form within the peritoneum and it can be a recurring condition even after successful treatment. Although cystic mesothelioma is rarely cancerous, the symptom of abdominal pain is experienced by most patients just as in cancerous peritoneal mesothelioma. Ascites, or fluid buildup between the peritoneum and abdominal organs, is common in malignant peritoneal mesothelioma, but is rarely present in cystic mesothelioma.

This particular type of mesothelioma is part of the epithelial cell variety and is difficult to diagnose. Cystic mesothelioma also has a variety of subcategories, including multicystic mesothelioma, microcystic mesothelioma and macrocystic mesothelioma. Information on all of these types is limited because of the low number of cases reported and the lack of a uniform approach to treatment.

Cystic Mesothelioma Types

In addition to receiving the general diagnosis of cystic mesothelioma, patients can be diagnosed with:

The medical community is unsure why some patients develop one type versus another, but all are usually benign and present the same symptoms since they almost always develop in the peritoneum. Treatment options are also the same for all cystic mesothelioma types.

multicystic

 

microcystic

 

macrocystic mesothelioma

Benign Cystic Mesothelioma

The most common location for benign cystic mesothelioma is the pelvic peritoneum of younger women. Many patients do not present symptoms and detection often occurs during unrelated testing or surgery. If symptoms are present, abdominal pain and lumps in the pelvic region are most common. Although diagnosing benign cystic mesothelioma is difficult, there are procedures that can help with detection.

One procedure that is used to diagnose cystic mesothelioma is a laparotomy. When used to diagnose an unknown condition, this surgical procedure is often called an exploratory laparotomy. It requires a large incision through the abdominal wall so that doctors can see into the abdominal cavity. A laparotomy can help doctors detect cysts and lesions that are commonly associated with cystic mesothelioma.

Another surgical procedure that can be used to diagnose cystic mesothelioma is a laparoscopy. Similar to a laparotomy, this procedure inserts cameras and other instruments through small incisions in the abdomen to provide a visual of suspicious areas. Other diagnostic tools used to detect cystic mesothelioma include ultrasound scans and CT scans.

Treatment for cystic mesothelioma is currently experimental. The most common treatment approach is surgery, which aims to remove all peritoneal cysts and lesions. Common procedures include cytoreductive surgery and a peritonectomy. Even when surgery is successful, recurrence of cysts and lesions is common in about 50 percent of patients. Follow-up treatment for cystic mesothelioma patients is usually expected and malignant development is possible (some rare cases have turned malignant), so monitoring the condition is standard following treatment.

For example, in one case report involving a 36-year-old woman diagnosed with benign cystic mesothelioma, doctors evaluated a series of surgeries spanning a 10-year period. After six surgical procedures designed to reduce the volume of intraperitoneal fluid and cysts, the disease developed into a malignant subtype known as diffuse malignant mesothelioma.

Unlike other types of mesothelioma where asbestos is the primary cause, doctors are unsure of the underlying causes of cystic mesothelioma. In many cases, patients have a history of previous pelvic operations or pelvic inflammatory disease.

Benign Multicystic Mesothelioma

Benign multicystic mesothelioma arises almost exclusively from the peritoneum, which is why this condition is also known as multicystic peritoneal mesothelioma. First described in 1979 by Mennemeyer and Smith, about 150 cases of multicystic mesothelioma have been reported. In extremely rare cases, the disease has been reported in the pleura and testis. Multicystic mesothelioma presents similar symptoms as other cystic mesothelioma types and is treated with the same surgeries.

This cystic mesothelioma subtype is very rare, often occurring in women in the reproductive age group. It is sometimes confused with multilocular cystic lymphangioma, but this condition is typically seen in males under the age of five. Surgery and follow-up treatment is important to managing the disease, but a standard treatment protocol is not available because of its rarity.

The factor uniting these theories is that asbestos leads to cellular damage that disrupts the natural cell cycle. Once normal function of the cell cycle is lost, cells begin to divide and grow uncontrollably. These cells then accumulate into tumors that trigger mesothelioma symptoms.

In a 2010 study conducted by the National Cancer Institute and the Mesothelioma Applied Research Foundation, researchers may have confirmed a primary way that asbestos causes mesothelioma. The study reported that asbestos damages cells through a process researchers dubbed "programmed cell necrosis." This process involves the release of a molecule known as "high-mobility group box 1 protein" (HMGB1), which triggers a chronic inflammatory reaction that causes tumor growth.

Microcystic and Macrocystic Mesothelioma

There is very little medical literature published on these rare subtypes of cystic mesothelioma. Microcystic mesothelioma is generally characterized by its cell shape, which is marked by lace-like spaces and lined with flattened cells. It can be observed with an Alcian blue stain (a popular staining method in pathology).

Macrocystic mesothelioma usually consists of one or several cysts with thin walls. These cysts often contain fluid and can be seen as a pale yellow color. The individual cells are flattened and may have the appearance of malignant mesothelioma.

Further Research on Cystic Mesothelioma

Cystic mesothelioma and its subtypes are in need of additional research to create a more standardized treatment plan for patients. Unfortunately, since the condition is so rare, it is unlikely to receive extensive funding for researchers to further evaluate treatment strategies. Prognosis remains positive, but common recurrence even after successful surgery suggests caution should be used when treating cystic mesothelioma.