Inclusion Criteria:

- Must be less than 30 years of age at time of diagnosis

- Must have biopsy-proven desmoid tumor (or aggressive fibromatosis). For patients
with recurrent disease, a biopsy is not required at the time of recurrence

- Patients known to have germ-line adenomatous polyposis coli (APC) mutations or
clinical manifestations of Familial Adenomatous Polyposis(FAP)/Gardner's syndrome can
be included

- Patients must have surgery planned to remove the desmoid tumor and either:

- the desmoid tumor has already recurred after a prior surgery or

- the newly diagnosed disease is judged to be at high risk for recurrence due to
its size (>5 centimeters) or location at an anatomic site making it unlikely to
be resected with negative margins (eg. adjacent to neurovascular structures)

- There must be a commitment by the surgical team to resect the primary tumor within 1
week following the 4 weeks of sirolimus unless the clinical situation at the time of
resection suggests that these interventions are not in the patient's best interest

- Concomitant medication restrictions:

- Patients may not have received prior chemotherapy (excluding prior mTOR
inhibitors

- Use of steroids for non-tumor indications (for example: asthma or severe
allergic reaction) is permitted

- Patients must have a Karnofsky performance status of greater than or equal to 50 for
patients older than 16 years of age or Lansky performance status of greater than or
equal to 50 for patients less than or equal to 16 years of age.

- Patients must have a life expectancy of greater than or equal to 8 weeks.

- Patients must have recovered from the acute toxic effects of all prior chemotherapy,
immunotherapy, or radiotherapy prior to entering this study

- Myelosuppressive chemotherapy: Must not have received within 2 weeks of entry
onto this study (4 weeks if prior nitrosourea)

- Biologic (anti-neoplastic agent): at least 7 days since the completion of
therapy with a biological agent

- Stem Cell Transplant (SCT): No evidence of active graft versus host disease.
For allogeneic SCT, greater than or equal to 6 months must have elapsed.

- Patients must be able to consume oral medication in the form of tablets or solution

- Patients must have normal laboratory values as defined below:

- Creatinine clearance or radioisotope Glomerular Filtration Rate ≥
70millileters/minute/1.73 meters2 or

A serum creatinine based on age/gender as follows:

Male Female

1 month to less than 6 months 0.4 0.4 6 months to less than 1 year
0.5 0.5

1. to less than 2 years 0.6 0.6

2. to less than 6 years 0.8 0.8

6 to less than 10 years 1 1 10 to less than 13 years 1.2
1.2 13 to less than 16 years 1.5 1.4 greater than or equal to 16
years 1.7 1.4

- Hepatic: Adequate liver function is defined as:

- Total bilirubin less than or equal to 1.5 x upper limit of normal (ULN)for age,
and

- Serum glutamic pyruvic transaminase (SGPT) less than or equal to 2.5 x upper
limit normal (ULN) for age

- Hematologic function: Adequate bone marrow function is defined as:

- Absolute Neutrophil Count (ANC) greater than or equal to 1 x 10 to the
ninth/Liter

- Hemoglobin greater than or equal to 10 gram/deciliter

- Platelet count greater than or equal to 100 x 10 to the ninth/Liter

- Female patients must have a negative pregnancy test

- Female patients who are lactating must agree to stop breast-feeding

- Sexually active patients of childbearing potential must agree to use effective
contraception

- Patients must be able to cooperate fully with all planned protocol therapy

- Signed informed consent MUST be obtained from patient or parent/legal guardian (if
patient is less than 18 years of age). Consent must be signed prior to any study
procedures and study entry

Exclusion Criteria:

- Patients with other fibroblastic lesions or other fibromatoses are NOT eligible.

- Concomitant medication restrictions

- Patients may NOT have received prior mTor inhibitors

- Growth factor(s): Must not have received within 1 week of entry onto this study.

- Patients must not be known to be Human Immunodeficiency Virus positive. Testing for
Human Immunodeficiency Virus is not mandatory.

- Patients must not be taking medicines known to influence sirolimus metabolism