Gleason grade 1 prostatic
adenocarcinoma is defined by its gland architecture, which resembles that of benign prostate more than any other grade. It is characterized by closely spaced glands and expansile
tumor border. Cytoplasm is clear to pale, superficially identical to benign nodular
hyperplasia (BPH). However, there is recent evidence that prostatic "clear-cell
carcinoma," including grade 1, has cytoplasm whose composition is distinctively different from BPH, being filled with
lipid rather than with the
protein-rich granules that characterize benign secretory cells or the nongranular
protein matrix of other
prostate cancers. We reasoned that grade 1
cancer might also have additional distinctive cellular features; we tested this hypothesis by observations on 17 grade 1
carcinoma foci found as components of transition zone clear-cell
cancers. Unlike BPH secretory cells, cells of grade 1
cancer were uniformly large with even, straight borders laterally and luminally. Nuclei appeared sometimes benign but were fixed in a basal row dissimilar to the uneven distribution in BPH. Nuclear pyknotic foci, blue-tinged cytoplasm, and abundant dense
luminal secretion were distinctively common. Immunostain for
glutathione-S transferase was negative in grade 1
cancer but lightly positive in BPH secretory cells. These cytologic findings were proposed to be useful as diagnostic clues, especially in small-needle biopsy samples, in which architecture may be difficult to interpret. HUM PATHOL 32:441-446.