[1252] Salivary Gland Lymphadenomas: Clinicopathological and Immunohistochemical Study

R Seethala, K Montone, S Kane, A Khan, L Barnes, ML Prasad. Yale University, New Haven, CT; UMass Memorial Medical Center, Worcester, MA; University of Pennsylvania, Philadelphia, PA; Tata Memorial Hospital, Mumbai, Maharashtra, India; Presbyterian University Hospital, Pittsburgh, PA

Background: Lymphadenomas (LAD) are rare major salivary gland neoplasms with prominent lymphoid stroma reminiscent of Warthin tumors. Categorized as sebaceous (SL) and non-sebaceous (NSL), their clinicopathologic profile and pathogenesis is unclear. These lesions may occasionally mimic nonkeratinizing squamous cell carcinoma or lymphoepithelial carcinomas, but to date the viral status of LAD has not been described. We report the clinicopathologic and immunohistochemical features of 16 cases.
Design: LAD were collected from various institutions. Clinical information, pathologic findings and immunohistochemical expression profiles were studied.
Results: 16 LAD were identified, 10 SL and 6 NSL, in 10 women and 6 men (F:M 1.6:1) aged 42 to 78 (median 60) years. 12 tumors arose in the parotid and 1 in the submandibular gland. 15 tumors presented as masses. All tumors were well-circumscribed, grey tan to yellow and homogeneous, measuring from 0.9 to 5.1 (median 2.2) cm. A well-formed capsule and cystic change was seen in 14/16 (88%) tumors respectively. Prominent lymphoid stroma was noticed in all, with germinal centers in 11 (69%). The epithelial component comprised of basaloid cells forming solid trabeculae, with tubules and glands in 11 tumors (69%). One SL showed oncocytic metaplasia while 1 NSL showed squamous differentiation with keratinization. Immunohistochemistry (IHC) showed that the epithelial cells were positive for p63 (10/10), CK7 (6/6) and essentially negative for calponin (6/6). Ki-67 showed no or low (<5%) proliferation in the epithelial cells (4/4). Moderate to strong expression of p16 protein was noted in epithelial cells in 2 cases. EBV, HPV and HHV-8 (KSHV) viral status were negative in 3, 1 and 1 case respectively. No recurrences were noted (follow-up 1-8 year) after surgical resection.
Conclusions: LAD are benign tumors with a slight female predilection unlike Warthin tumors. Based on limited data, LAD are not virally driven which in conjunction with the well demarcated bland appearance, may be useful in distinguishing these tumors from metastatic non-keratinizing squamous cell carcinoma or lymphoepithelial carcinoma, however, strong expression of p16 protein in two cases warrants more extensive validation of this concept.
Category: Head & Neck

Wednesday, March 24, 2010 9:30 AM

Poster Session V # 158, Wednesday Morning

 

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