[1151] Striated Duct Adenoma: A Report of 3 Cases of a Distinctive Lesion of Salivary Gland

I Weinreb, B Perez-Ordonez, R Chetty, I Dardick, JL Hunt. University Health Network, Toronto, ON, Canada; Cleveland Clinic Foundation, Cleveland, OH

Background: Benign tumors of salivary gland can be separated into pleomorphic adenoma, basal cell adenoma, myoepithelioma and others based on their cell constituents and architectural patterns. Most of these benign salivary gland tumors contain a myoepithelial/basal cell component, with the exception of canalicular adenoma. Normal striated ducts in salivary gland show a single ductal layer with only patchy or absent basal/myoepithelial cells. To our knowledge there has been no benign neoplastic ductal lesion described that is composed primarily of striated ducts with no myoepithelial contribution.
Design: Three cases of striated duct adenomas were collected from the consultation files of the authors and reviewed. Each case was stained with various keratins, p63, actin and S100.
Results: The cases were from parotid (2) and oral cavity (1). They ranged from 0.9-2.4 cm. Two patients with clinical data were females of 47 and 57 years of age. All 3 cases were encapsulated/circumscribed masses. The tumors were made up entirely of back-to-back ducts with virtually no intervening stroma. The ducts were of varying size with large caliber lumina containing eosinophilic secretions. Interspersed ducts formed cysts up to 1 mm in diameter. The ductal cells were eosinophilic, had visible striations and bland basally oriented nuclei. All lesions contained abundant large vessels, some of which were staghorn in shape. One case contained psammoma bodies and focal papillary formations. None of the cases showed the typical epithelial beading pattern with abundant stroma seen in canalicular adenomas. One case had striated duct hyperplasia (SDH) in the background parotid. All 3 cases and SDH were positive for keratins and S100. Normal salivary elements were S100 negative. No basal/myoepithelial contribution was found with p63 or actin in the tumors or in the background SDH: a pattern identical to normal striated ducts and unlike acini, intercalated and excretory ducts (which all contain basal or myoepithelial cells). CK5/6 in one case demonstrated strong positivity with basal accentuation, which was again identical to the background striated ducts.
Conclusions: Striated duct adenoma is a rare unilayered ductal lesion with virtually no stroma and no myoepithelial component. These neoplasms recapitulate normal striated ducts morphologically and immunohistochemically. Striated duct adenoma is distinct from all other benign salivary gland lesions, including canalicular adenoma.
Category: Head & Neck

Monday, March 9, 2009 1:00 PM

Poster Session II # 161, Monday Afternoon