Chaipak Sithinatesakul, MD*., Vorachai Sirikulchayanonta, MD**
*Department of Surgery, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
** Department of Pathology, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand Received : 12 May 2014 ; Accepted : 2 June 2014
Pseudosarcomatous fibroblastic proliferation (PSFP) is a quite common lesion found in various locations in- cluding soft tissue, bone and other organs and often raises a difficult differential diagnosis with malignancy. However, PSFP has not been described in tissue related to bursitis. We report a case of 31-year-old male who developed a cystic lesion in association with a bursitis. Histologically, this showed the presence of sheets of pleomorphic cells with mitosis and mimicked myxofibrosarcoma and angiosarcoma. The findings of ganglion- like cells, metaplastic bone formation and the clinical history of a short incubation period supported the diag- nosis of pseudosarcomatous lesion. Consideration of PSFP as a mimic of soft tissue tumours is important for avoiding the pitfall of a malignant diagnosis.