Welcome to the Rare Classroom, a new series from Patient Worthy. Rare Classroom is designed for the curious reader who wants to get informed on some of the rarest, most mysterious diseases and conditions. There are thousands of rare diseases out there, but only a very small number of them have viable treatments and regularly make the news. This series is an opportunity to learn the basics about some of the diseases that almost no one hears much about or that we otherwise haven’t been able to report on very often.

Eyes front and ears open. Class is now in session.

The rare disease that we will be learning about today is:

Atypical Teratoid Rhabdoid Tumor

What is Atypical Teratoid Rhabdoid Tumor?

• Atypical teratoid rhabdoid tumor (AT/RT) is a rare central nervous system tumor that is often identified in childhood
  • Typical onset is age three or younger
  • This tumor is usually found in the brain, but it can be found throughout the CNS
• About 30 cases are diagnosed annually in the US, which equates to a prevalence rate of three in 1,000,000
• Atypical teratoid rhabdoid tumor was only first formally described in 1996 and recognized as a distinct diagnosis in 1987
• Its overall rarity leads to frequent misdiagnosis and poor treatment, leading to a history of poor outcomes

How Do You Get It?

• The cause of these tumors isn’t clear, but rhabdoid tumors tend to share genetic similarities, such as chromosomal 22 deletion
• Chromosome 22 holds the hSNF5/INI1 gene, which function as a tumor suppressor
• Risk within families also isn’t well understood, though there have been some reports of atypical teratoid rhabdoid tumors and other rhabdoid tumors appearing within family members

What Are the Symptoms?

• The symptoms of atypical teratoid rhabdoid tumor vary depending on the tumor location. As many tumors appear in the posterior fossa region of the brain, symptoms are similar to other tumors that appear in this region and may include:
  • Ataxia (gait abnormalities)
  • Headaches
  • Lethargy
  • Vomiting
  • Abnormally large head size in infants

How Is It Treated?

• Determining the best treatment for atypical teratoid rhabdoid tumor is a subject of ongoing research
• Survival rates increase significantly when the correct diagnosis is made in a timely manner and appropriate, multimodal therapy is employed
• Treatment approaches include:
• Surgery
  • Surgery alone cannot cure this tumor, but is typically essential to confirm the diagnosis
  • Total removal of the tumor is rarely possible
• Chemotherapy
  • Chemotherapy is typically used as part of treatment, but is most effective in combination with other approaches
  • Around half of tumors will temporarily respond to chemotherapy
  • A variety of chemotherapy agents have seen use
• Radiation therapy
  • Radiation is increasingly used as part of a first-line treatment approach
  • While there is no standard regimen in use, radiation does seem to increase survival in most cases
• Generally, survival rates in atypical teratoid rhabdoid tumor are poor. Five-year-survival rate is around 32%, though some studies have reported more favorable outcomes.

Where Can I Learn More???

• Check out our cornerstone on this disease here.
• Learn more about this disease from the National Cancer Institute.