Intercalated Duct Lesions of Salivary Gland: A Re-Appraisal of 30 Cases of a Putative Precursor Lesion
I Weinreb, RR Seethala, JL Hunt, R Chetty, I Dardick, B Perez-Ordonez. University Health Network, Toronto, ON, Canada; University of Pittsburgh Medical Center, Pittsburgh, PA; Cleveland Clinic Foundation, Cleveland, OH
Background: Intercalated duct lesions (IDL) are benign ductal proliferations that have been described rarely in association with epithelial-myoepithelial carcinoma (EMC) and are also seen in association with other salivary gland tumors. They have been proposed as a putative precursor lesion, but a detailed review of IDL's has not been performed.
Design: 30 cases of IDL were identified and reviewed and immunostaining with CK7, ER, PR, lysozyme, S100, CK14 and calponin was performed. Due to the morphologic resemblance to basal cell adenoma (BCA), 8 of these tumors were stained for comparison.
Results: The patients with IDL ranged in age from 19-80 yrs (average 53.2). There was a 1.8:1 female predominance. The majority were parotid lesions (25/30 - 83%) with the remaining cases in submandibular gland. Most cases (24/30 - 80%) were small nodular lesions ranging from 1-8 mm (average 3.2 mm). The remainder were diffuse/multifocal lesions. 16 IDL's (53%) were seen in conjunction with another salivary gland tumour, the most common being BCA/BC adenocarcinoma (7 cases). The IDL's showed a spectrum from irregular ductal proliferations to round encapsulated adenomas with hybrid forms. 1 case showed a direct transition from IDL to a BCA. Focal acinic differentiation was common. Most cases had an indistinct myoepithelial layer on H&E, however some demonstrated a focal clear cell myoepithelial layer. Others had periductal hyalinization. Immunohistochemically, IDL's stained diffusely for CK7 (100%) and S100 (71%) and focally for lysozyme (100%) and ER (88%). They were negative for PR. Normal intercalated ducts also showed consistent CK7, lysozyme and focal ER staining but were S100 negative. A thin myoepithelial layer was highlighted with CK14 and calponin in all IDL's (100%) and in normal intercalated ducts. In contrast, BCA's were larger (average 2.1 cm), did not show significant ER or lysozyme staining and had a more prominent neoplastic basal/myoepithelial component with these markers.
Conclusions: IDL's have a variety of growth patterns. They share features with normal intercalated ducts. They are distinct from BCA's which have a biphasic neoplastic population. However transition to and association with BCA's is common and appears more common than with EMC. Their frequent occurence in association with salivary tumors lends credence to their role as a precursor lesion.
Category: Head & Neck
Tuesday, March 10, 2009 2:30 PM
Platform Session: Section H, Tuesday Afternoon