[Fordyce's spots: disease, heterotopia or adenoma? Histological and ultrastructural study].

Fordyce spots are sebaceous glands without hair follicles, most often located under the epithelium of the cheek and free lip border. These glands, present in 80 to 95% of adults, according to the localization, cannot be considered as ectopic. Along the same lines, these spots are neither a disease, a lesion or an adenoma. These glands are acino-tubular and distributed in clusters. They are connected to the covering epithelium by a duct with a keratinizing stratified epithelium. By analog to what has been done in the skin, the acinous cells can be artificially classified in three groups: basal germinative cells partially differentiated intermediary cells and totally differentiated preductal cells. With PAS-Mac Manus, the peripheral cells are characterized by a reduced cytoplasm, the scarcity of organelles, as well as the presence of tonofilaments and desmosomes. The intermediary cells have a low nucleus-cytoplasm ratio. While keeping their epidermal characters, they become rich in lipid droplets of variable sizes and are closely related to numerous mitochondria. The cytoplasm of completely differentiated cells, with unrecognizable organelles, are invaded by large lipid globules. In the periacinous connective tissues, fenestrated capillaries are observed.