Adenomatoid hyperplasia of minor salivary glands: report of three cases with immunohistochemical findings and literature review.

Adenomatoid hyperplasia (AH) is an infrequent intraoral lesion, composed of lobular aggregates of hyperplastic normal-appearing salivary glands (SG). Three cases of adenomatoid hyperplasia of minor salivary glands (AHMSG) are reported: two were located on the hard palate, in a female patient aged 41 and in a male aged 85 years, and one in the lower lip, in a male patient aged 37. Histopathologically, lesions showed enlarged lobules of mucous or mixed acini with dilated salivary ducts and fibrous stroma. Immunohistochemically, acinar cells were positive for CAM 5.2 and cytokeratin 7 (CK7) and negative for epithelial membrane antigen (EMA) and carcinoembryonic antigen (CEA); myoepithelial cells were positive for p63 and smooth muscle actin (SMA); luminal cells of intercalated, striated and excretory∕interlobular ducts were positive for CK7, CAM 5.2, EMA and sex-determining region Y (SRY)-box transcription factor 10 (SOX10); basal ductal cells, positive for CK7 and CAM 5.2, also stained with p63; Ki67 labeling index ranged between 1% and 5%. AHMSG is a lesion to be recognized to avoid clinical overdiagnosis, since it can simulate a benign or malignant SG tumor, and to prevent histological underdiagnosis, since hyperplastic SG, showing a normal cyto-architectural structure, may suggest the absence of pathology.