Serous extravasation granuloma. A parotid mass.

A new benign lesion of the parotid gland, the serous extravasation granuloma, occurred as a unilateral, painless parotid mass. Histologically, the mass was outlined by a fibrous capsule within which there was granulation tissue that was admixed with histiocytes and giant cells of a foreign-body type with abundant PAS-positive granules in their cytoplasm. Atrophic duct spaces and microsialoliths occurred within the lesion. Trauma to the parotid gland was the proposed origin.