Inclusion criteria:

1. Patients ≥ or equal to 18 years of age.
2. Suspected or documented diagnosis of dermatofibrosarcoma protuberans (DFSP). Patients with suspected diagnosis of DSFP must have DFSP confirmed by pathology at the local institution prior to dispensing and the start of imatinib.
3. Patient is medically able to undergo surgical resection of the DFSP and resection of the DFSP is recommended for clinical management of the disease.
4. Patient has at least one site of measurable (macroscopic) disease.
5. Performance status 0, 1 or 2 Eastern Cooperative Oncology Group (ECOG) (see Section 7.1).

6. Adequate end organ function, defined as the following:

   total bilirubin < 1.5 x institutional upper limit of normal (ULN), SGOT and SGPT < 2.5 x UNL, creatinine < 1.5 x ULN, absolute neutrophil count > 1.5 x 109/L, platelets > 100 x 109/L.

7. Female patients of childbearing potential must have negative pregnancy test within 7 days before initiation of study drug dosing. Postmenopausal women must be amenorrheic for at least 12 months to be considered of non-childbearing potential. Male and female patients of reproductive potential must agree to employ an effective barrier method of birth control throughout the study and for up to 3 months following discontinuation of study drug.
8. Written, voluntary informed consent.

Exclusion criteria:

1. Patients who will receive radiation therapy to the site of DFSP prior to resection.
2. Patients with Grade III/IV cardiac problems as defined by the New York Heart Association Criteria (i.e., congestive heart failure, myocardial infarction within 6 months of study).
3. Female patients who are pregnant or breast-feeding.
4. Patients who have a severe and/or uncontrolled medical disease (i.e., uncontrolled diabetes, chronic renal disease, or active uncontrolled infection) that may worsen because of imatinib.
5. Patients who have known chronic liver disease (i.e., chronic active hepatitis, and cirrhosis).
6. Patients who have a known diagnosis of human immunodeficiency virus (HIV) infection.
7. Patients who have received chemotherapy within 4 weeks prior to study entry.
8. Patients who have had a major surgery within 2 weeks prior to study entry. Incisional biopsy or partial excision of dermatofibrosarcoma protuberans to establish the diagnosis and/or to collect pretreatment tumor tissue does not qualify as major surgery.