Diagnostic Dilemma of Polymorphous Low Grade Adenocarcinoma of Hard Palate

Abstract

Abstract:Polymorphous low grade adenocarcinoma (PLGA) is an indolent malignant tumor affecting the minor salivary gland almost exclusively. It is important to differentiate PLGA from other salivary gland tumors with myoepithelial differentiation such as pleomorphic adenoma and adenoid cystic carcinoma.We report a case of a 55 year old male who presented with an asymptomatic swelling on the hard palate for the past one year. FNAC of the swelling was suggestive of pleomorphic adenoma and surgical excision with adequate margins was done. Histopathological and immunohistochemistry examination of the excised specimen came out to be PLGA. A very inquisitive work up including adequate sized biopsy and immunohistochemistry is recommended for the diagnosis of PLGA. The clinician and the cytopathologist should be aware of the characteristic cytomorphologic and immunohistochemistry features of PLGA to distinguish it from pleomorphic adenoma as happened in the present case.

The Unusual Tales of Arch and Nape

“…There lies a problem in distinguishing PA with PLGA due to presence of infiltrative margins where the capsule is incomplete and also presence of hyaline in the stroma in a limited PLGA specimen can be mistaken for mucomyxoid matrix of PA and a wrong diagnosis can be rendered, a similar thing happened in the present case [22]. IHC stands as an important tool in its differential diagnosis, PLGA cells show positivity for CK 7, Vimentin and S100 while being negative for glial fibrillary acid protein (GFAP), however PA is positive for GFAP and no immunoreactivity to Vimentin [20]. To conclude the pathologist should be aware of the characteristic morphologic and IHC findings of PLGA in order to differentiate it from PA, thus an inquisitive work up with adequate size biopsy and IHC are ideal for its diagnosis.…”

“…Polymorphous low grade adenocarcinoma (PLGA) is an indolent malignant tumor affecting the minor salivary glands almost exclusively. It is characterized by low metastatic potential, infiltrative growth pattern, cytological uniformity and morphological diversity [20] PLGA comprises 9-26% of all salivary gland malignancies, constituting as the second most common primary minor salivary gland malignancy after mucoepidermoid carcinoma. 21 PLGA is found to have myoepithelial differentiation and thus it is of utmost significance to differentiate it from other salivary gland tumors having myoepithelial differentiation like pleomorphic adenoma (PA) and adenoid cystic carcinoma(ACC) [20].…”

“…It is characterized by low metastatic potential, infiltrative growth pattern, cytological uniformity and morphological diversity [20] PLGA comprises 9-26% of all salivary gland malignancies, constituting as the second most common primary minor salivary gland malignancy after mucoepidermoid carcinoma. 21 PLGA is found to have myoepithelial differentiation and thus it is of utmost significance to differentiate it from other salivary gland tumors having myoepithelial differentiation like pleomorphic adenoma (PA) and adenoid cystic carcinoma(ACC) [20]. There lies a problem in distinguishing PA with PLGA due to presence of infiltrative margins where the capsule is incomplete and also presence of hyaline in the stroma in a limited PLGA specimen can be mistaken for mucomyxoid matrix of PA and a wrong diagnosis can be rendered, a similar thing happened in the present case [22].…”