A case of lipoma-like tumor causing clinical symptoms of sciatic neuralgia is presented. The tumor was located deep underneath the greatest gluteal muscle, protruding into the pelvis minor. The cause of the patient's complaints remained unclear for about 1 year. Then a considerable growth of the tumor resulted in appropriate diagnostics and therapy. The presented case is an example of late diagnosis due to atypical location of the lesion, not readily accessible for clinical and accessory investigations.

Keywords: tumor, Lipoma, Retroperitoneal Space, sciatic neuralgia