[Desmoplastic fibroma on arm of 22-year-old woman]

Desmoplastic fibroblastoma ("collagenous fibroma") is a rare benign, slowly progressive fibrous soft tissue tumor that ranges 1-20 cm in size. The tumor occurs in all ages, predominantly in the upper part of the body. Children are rarely affected. The tumor often infiltrates the subcutis; less often it invades the fascia and skeletal muscle or causes bone erosions. Histologically, the tumor is composed of spindle-shaped cells embedded in a densely collagenous stroma, sometimes forming a pseudo-capsule. Magnetic resonance imaging and computed tomography as well as ultrasonography are used to define the extensions of the tumor. Because it is clinically extremely difficult to determine if soft tissue tumors are benign or malignant, all should be excised with a margin of safety and examined histologically. We report a 22-year old woman with desmoplastic fibroblastoma located on the upper arm. Clinical and histopathological findings and treatment options are discussed.