What Is Desmoplastic Small Round Cell Tumor

Desmoplastic small round cell tumour is a rare cancer originating from soft tissues/supporting tissues of the body and occurs primarily in the abdomen in young people. It usually presents with abdominal symptoms and is often found to have advanced disease at presentation. The cancer has a specific genetic abnormality and has a generally poor outcome due to being resistant to treatment and prone to recurrence.

Desmoplastic small round cell tumour is a cancer of the sarcoma family, also known as soft tissue tumours. This means cancer originating from soft tissue/connective tissue as opposed to those originating from the lining cells of organs or those from blood cells. The name comes from the microscopic appearance of the cancer, which causes some scarring-like effect known as ‘desmoplasia’ on the microscopic view. As for the rest of the terminology, several cancers belong in the microscopic description category of ‘small, round cell tumours’.

Desmoplastic small round cell tumour has a specific genetic abnormality, which is often tested  to confirm its diagnosis. The cancer primarily occurs in the abdominal or thoracic cavity but can spread to other organs and lymph nodes quickly.  Desmoplastic small round cell tumour is primarily treated by surgical resection in combination with other modalities like chemotherapy and radiation.

Who gets desmoplastic small round cell tumours?

This is a cancer of mostly young people. This can mean children and adults even up to about the fifth decade, but the peak occurrence is reported to be in those in the third decade.¹ The cancer is reportedly more common in those assigned male at birth (AMAB) than those assigned female at birth (AFAB).¹

What are the symptoms of desmoplastic small round cell tumour?

This cancer commonly occurs in the abdominal cavity. Therefore the symptoms are generally related to the abdomen, including pain and fullness in the abdomen and sometimes constipation. There are no symptoms specific to this cancer. Other than the abdomen, it can also occur in the chest cavity or around the testicular area in those assigned male at birth (AMAB).¹

In addition, the cancer can also spread to lymph nodes and other organs quite rapidly and cause symptoms. These organs include the liver, bone and lungs.⁵

What investigations will be done initially if a desmoplastic small round cell tumour is suspected?

The diagnosing procedure will start with a history and examination.

Abdominal or chest symptoms will lead to chest and abdominal examination, which may reveal a mass. Lymph nodes may be palpated if enlarged due to cancer spread. 

Your doctor will then order an ultrasound scan of the abdomen, which will often reveal a mass with a lobulated or nodular appearance with increased vessels and sometimes calcifications.²

A CT  or MRI scan can also demonstrate this cancer. PET/CT scans will show a characteristic high FDG activity. Spread to other organs also will also be detected by scans.

What are the tests for definitive diagnosis of desmoplastic small round cell tumour?

The diagnosis of this cancer comes from tissue sampling and viewing it under microscopy. However, sometimes, the microscopic appearance and additional lab test results overlap with other similar cancers, so the genetic abnormality needs to be tested to confirm the diagnosis.⁴

How does a biopsy help to diagnose desmoplastic small round cell tumours? 

A biopsy is a sampling of the cancer mass, which is then processed in the laboratory and viewed under the microscope. Desmoplastic small round cell tumour, as the name suggests will show small, round, cells with some scarring-like effect which is called ‘desmoplasia’.3 However, since there are several cancers with a similarly small, round cell appearance, special tests called immunohistochemistry will be done on the biopsy. This essentially means a type of painting or staining of certain cells that will light up under the microscope, revealing a pattern specific to this cancer. 

Despite those tests, some features tend to overlap with other similar cancers. Therefore, genetic abnormalities are often tested to confirm the diagnosis.

How is the testing for the genetic abnormality done?

The genetic abnormality in this cancer is a mix-up or exchange of material between two units of genetic components that occur in our body. These can be detected by a test called FISH, (fluorescence in situ hybridization), which shows lighting up of the mixed up or exchanged genetic material. The test is performed on a processed sample of cancer tissue.

How is a desmoplastic small round cell tumour treated?

There are a few treatments available.⁸

• Surgery - This is one of the main components of treatment done to remove the cancer. Sometimes, it may not be possible to remove the entire cancer, and some cells may remain behind. These can in turn regrow back.⁵ This cancer is well known to recur this way.
• Chemotherapy - This is a treatment method using special medication that is capable of killing cancer cells. This drug is given systemically, meaning to the whole body, and this can have effects on other organs of the body, leading to side effects. This treatment is often given in combination with the surgery.⁷
• Hyperthermic intraperitoneal chemotherapy:⁵ This is a procedure whereby medication which can kill cancer cells is used to wash the abdominal cavity where the tumour was removed surgically.⁵ The treatment is meant to kill the remaining cancer cells. This method has the advantage of killing the cancer cells in the target area of the body without subjecting the entire body to the side effects.⁵
• Radiation therapy: This treatment uses radiation to kill cancer cells. External radiation means having a machine externally that targets the area of the cancer in the body. Internal radiation means placing a source within a body cavity, such as a seed or capsule, that emits radiation and kills cancer cells.⁵

What is the outcome of a desmoplastic small round cell tumour?

The outcome for this cancer depends on where the cancer occurred in the body,⁶ whether it has spread to other organs and also how much cancer was removed during surgery.⁵

In general, this is an aggressive cancer that can spread along the inner body cavity lining, lymph nodes and to other organs quite easily.

Even after resection, the cancer tends to recur. Some reports claim the five-year survival rate to be about 15%.⁵

How can I prevent desmoplastic small round blue cell tumour?

Since there are no definitive causative factors for this cancer, specific preventive measures are not possible. Noticing changes in your body and symptoms and addressing them quickly is one of the most important things for any cancer as it helps to catch it at an early stage.

Living with desmoplastic small round blue cell tumour

Living with a desmoplastic small round blue cell tumour (DSRCT) can be an incredibly challenging journey. DSRCT is a rare and aggressive type of cancer that primarily affects young people, making it even more emotionally difficult. Coping with the physical and emotional toll of this disease, along with the demands of treatment, can be overwhelming. Patients and their loved ones often find themselves navigating a complex healthcare system, enduring chemotherapy, radiation, and surgeries, all while striving to maintain hope and a sense of normalcy. The support of friends, family, and a medical team experienced in treating DSRCT is essential in facing this diagnosis with courage and resilience. Despite its difficulties, many individuals with DSRCT demonstrate remarkable strength and determination in their battle against this formidable foe.

Summary

Desmoplastic small round cell tumour is a rare cancer of young people with peak occurrence in the third decade. This cancer originates from the soft tissues of the body and usually occurs in the abdominal cavity or thoracic cavity. It has a specific genetic abnormality that can be detected by a special test. There are no symptoms specific to the cancer, but they cause local effects depending on where the cancer is located. Since the abdomen is a common site, abdominal pain, discomfort, and constipation are some of the commonly known symptoms. 

If suspected, the tumour can be checked up with scans like ultrasound scans or other advanced scans like PET scans or MRI, which will show a characteristic nodular appearance with high uptake on PET scans. The definitive diagnosis includes sampling of cancer and checking with microscopy as well as a test to detect the genetic abnormality.

This is an aggressive cancer with generally poor outcomes. The treatment includes surgery, chemotherapy and radiotherapy. Despite this, this cancer tends to recur. There are no special methods to prevent this cancer. Getting checked up for your symptoms early is the best way to diagnose this cancer, and like most others, that can lead to a better prognosis.