Polymorphous low-grade adenocarcinoma of the upper lip : 11 cases of an uncommon diagnosis

Abstract

OBJECTIVE : To describe an international case series of polymorphous low-grade adenocarcinoma (PLGA) affecting the upper lip. MATERIAL AND METHODS : Over a 30-year-period the files of five pathology services were reviewed for PLGA cases affecting the upper lip. Hematoxylin and eosin-stained slides were reviewed by three oral and maxillofacial pathologists and the microscopic features were described. Clinical data were retrieved from patients’ medical records. RESULTS : The review identified 11 upper lip PLGAs, with a complete set of clinical data available for 5 cases. There was male predominance (1.2:1) and a mean age of 58.7 years. Most cases presented as small asymptomatic swellings resembling benign tumors. All patients were surgically treated and no recurrence or metastases were reported in the 8 cases from which follow-up data was available. Microscopically, the typical polymorphic architectural arrangement of PLGA was seen in all cases, with lobular, trabecular, papillary and cribriform patterns identified. Perineural invasion, normal gland entrapment, Indian filing and concentric growth were frequently identified. CONCLUSION : PLGA must be included in the list of differential diagnoses of tumors affecting the upper lip because of its similar clinical presentation to benign entities. The follow-up data available from 8 of 11 cases suggests that these tumors follow a low grade clinical course, similar to the majority of palatal cases of PLGA.