Clinical history: 50-year old man with progressively enlarging left upper arm mass for one year

Diagnosis: Dermatofibrosarcoma protuberans

Imaging techniques:

Imaging of the left upper arm was performed on a 3T MR system (Skyra, Siemens). (A) Coronal T2-weighted TIRM (TR/TE 2734/38), (B) axial T1-weighted TSE (TR/TE 500/12ms), and (C) axial T2-weighted TSE images with Dixon fat suppression (TR/TE 2650/85ms) were acquired along with RESOLVE DWI images (TR/TE 6600/54, b=0,500 and 1000) in the axial plane (D,E).

Imaging findings:

A large, well-defined mass is located within the subcutaneous tissues of the mid left upper arm. The lesion is 10 cm by 7 cm by 5 cm in size. On pre-contrast MR imaging, the lesion exhibits predominantly intermediate to slightly high signal on T1WI and markedly heterogenous high signal on FS T2WI. Small foci of prolonged T2 signal are seen on T2WI, suggestive of intratumoral cysts and necrosis. The majority of the lesion demonstrates increased signal intensity on DWI and relatively low values on the ADC map.