Oxyphilic granular cell adenoma (oncocytoma)--a histochemical and ultrastructural study.

: Oxyphilic granular cell adenoma (oncocytoma) is extremely rare usually benign neoplasm. Specimens from four oncocytomas of the parotid gland were studied by light microscopy using different histochemical stains, and by electron microscopy. The haematoxylin and eosin stained sections revealed large cells with eosinophilic granular cytoplasm. These granules appear blue with phosphotungstic acid haematoxylin stain, purplish blue with mallory aniline blue stain and are moderately reactive to alcian blue and PAS. No elastic fibers could be seen in the intercellular substance using Verhoeff's stain. At the ultrastructural level, the tumour cells were characterized by great numbers of mitochondria. Many of the mitochondria contained glycogen granules. Dividing mitochondria were also observed.