Oncocytic lipoadenoma of the parotid gland: Immunohistochemical and cytogenetic analysis.

Salivary gland oncocytic lipoadenoma is an exceptional benign tumor composed of mature adipose tissue associated with a mixture of oncocytes. We report a case of oncocytic lipoadenoma showing sebaceous differentiation, and provide a cytogenetic analysis, which has not yet been described. A 64-year-old male developed a left parotid gland, well-encapsulated tumor measuring 3.5 x 3 cm(2), showing mature fat cells associated with oncocytic changes of epithelial components. Immunohistochemistry showed a dual epithelial population with ductal (positivity for AE1/AE3, CK19, CK7 antibodies) and basal-cell (positivity for p63, CK14, CK5,6 antibodies) differentiation in oncocytic areas. Moreover, oncocytic cells were stained with anti-alpha-1 antichymotrypsin antibody and phosphotungstic acid-hematoxylin staining. Molecular cytogenetic analysis showed a translocation t(12;14), resulting in structural rearrangement of the region framing the HMGA2 gene at 12q14.3. Such alterations in HMGA2 have been described in both lipomas and pleomorphic adenomas of the salivary glands. Copyright 2009 Elsevier GmbH. All rights reserved.