Renal angiomyolipoma (pathology)


The textbook 'tri-phasic' appearance is not always present which can pose a diagnostic dilemma. As pathologists, we are seeing more core biopsies taken to try and identify the tumor type. On histology, the typical three components (vessels, smooth muscle and fat) are seen in variable proportions, but ‘monophasic’ (only one component) and ‘biphasic’ (two components) can be seen, especially if the tumor is only minimally sampled (e.g. core biopsy). Tumor cells are usually positive on immunohistochemistry for HMB45, CD117, CD63, and negative for cytokeratin and other epithelial markers.