Histological section of the cyst. Sub-mucosal nodule in the cheek with Dirofilaria (Nochtiella) repens Railliet & Henry, 1911. (A). A granulomatous immune response (B) is observed with abundant inflammatory mononuclear lymphocytes, a few mast cells typically with purple-violet granulations, some eosinophils, and rare neutrophils. Some binuclear cells can also be observed (C).