<unk> s occur in 10-20 per one million people. The true incidence might be higher, as novel laboratory methods are much more sensitive in diagnosing<unk> s. The estimated incidence of<unk>  in the United States is approximately 5000 cases annually. This makes<unk>  the most common form of sarcoma, which constitutes more than 70 types of cancer. The majority of<unk> s present at ages 50–70 years. Across most of the age spectrum, the incidence of<unk>  is similar in men and women. Adult<unk> s are rare before age 40. Pediatric<unk> s are considered to be biologically distinct. Unlike<unk> s at other ages, pediatric<unk> s are more common in girls and young women. They appear to lack oncogenic activating tyrosine kinase mutations in both KIT and PDGFRA. Pediatric<unk> s are treated differently than adult<unk> . Although the generally accepted definition of pediatric<unk>  is a tumor that is diagnosed at the age of 18 years or younger, "pediatric-type"<unk> s can be seen in adults, which affects risk assessment, the role of lymph node resection, and choice of therapy.
Gastrointestinal stromal tumor
Ectopic pancreas
Krukenberg tumor
Signet ring cell carcinoma
Lipoblastoma
Nesidioblastoma
Angiomyofibroblastoma
Myxoid cyst