prostatic stromal tumour of uncertain malignant potential prostatic stromal tumour of uncertain malignant potential prostatic stromal tumour of uncertain malignant potential (pstump) is a rare tumour of the prostate gland stroma that may behave benign or like cancer. prostatic stromal tumour of uncertain malignant potentialother namesprostatic stromal proliferation of uncertain malignant potential (pspump)prostatic stromal tumour of uncertain malignant potential. h&e stain. it can be abbreviated stump; an abbreviation used for a uterine lesion of uncertain malignant potential.