Prostatic adenocarcinoma metastatic to pleomorphic liposarcoma, a "collision phenomenon": report of a case with review of pelvic collision tumors.

[pleomorphic liposarcoma]

"Collision tumor " is an uncommon phenomenon characterized by coexistence of two completely distinct and independent tumors at the same site . Collision tumors have been reported in different sites in the body ; however , these are particularly uncommon in the pelvic cavity . A 70 -year -old man , with prior history of urothelial and prostate cancer , presented with a large pelvic mass detected on imaging studies . Pathological examination revealed a large liposarcoma with prostatic carcinoma embedded in it . Immunohistochemistry and florescence in situ hybridization studies were performed to reach to a conclusive diagnosis . To the best of our knowledge , this is the second case reported till date . We present the challenges encountered in the diagnosis of this case and review of pelvic collision tumors .