Microscopic Description -- Hypertension of Unknown Etiology


Slide 1 and slide 2 show a renal mass which is composed of two distinct components surrounded by a mature collagenous capsule and a rim of compressed renal tissue. The border between each cell type is distinct. Slide 3 and slide 4 show the peripheral zone of the mass which consists of large, polygonal cells with clear cytoplasm arranged in an alveolar growth pattern with uniform, round nuclei and inconspicuous nucleoli. Slide 5 and slide 6 show the central zone of the mass which consists of fairly uniform epithelioid cells arranged in a trabecular growth pattern and surrounded by a rich vascular network. At low magnification, these elongated, branching blood vessels confer a hemangiopericytoma-like growth pattern upon the tumor. At higher magnification, slightly pleomorphic nuclei are seen which are surrounded by a finely granular cytoplasm. No mitoses are observed. Slide 7 shows diffuse hyperplasia of the zona glomerulosa of the adrenal gland.


Slide 8, slide 9, and slide 10 are electron micrographs taken from the central zone of the mass showing the characteristic ultrastructural intracytoplasmic granules of a juxtaglomerular tumor. Two types of granules are seen. The more frequent granules are round and electron dense and represent mature renin. The less frequent granules are sharply angulated with a periodic crystalline substructure and represent the immature protogranules of renin.

Final Diagnosis


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