Hyaline ring granuloma of vegetable: Report of two cases with histochemical and immunohistochemical study.

BACKGROUND: Peripheral hyaline ring granuloma is a rare lesion characterized by the presence of hyaline rings and multinucleated giant cells. Its pathogenesis is related to exogenous factors such as vegetal origin, resulting in foreign body reaction mediated by macrophages against cellulose particles. We report two cases: a 58-year-old male with a lesion in the maxillary alveolar mucosa measuring 1.0cm×1.0cm; and a 50-year-old female presenting a slight swelling in the alveolar mucosa, measuring 0.7cm×0.7cm and diagnosed as asymptomatic sessile nodule of fibrous consistency. Microscopic examination revealed a dense connective tissue with focal area of concentric hyaline collagen deposition and multinucleated giant cell granulomas of foreign body type. Immunohistochemical study was positive for anti-CD68/anti-α-SMA, confirming the foreign body reaction and vascular integrity. Histochemical analysis for PAS with and without diastase and van Gieson highlighted the vegetable exogenous origin of foreign material. Additionally, we performed a review of 7 cases published in the literature in the last 10 years.