PURPOSE: Polymorphous low-grade adenocarcinoma (PLGA) is a salivary gland malignancy characterized by indolent growth and a low rate of metastasis. PLGA shares histological features with adenoid cystic carcinoma (ACC), including infiltrating solid and cribriform patterns, presence of cystic spaces, and neurotropism. The degree of polymorphism of PLGA presents diagnostic challenges, particularly in small biopsy specimens. Immunohistochemical reactions to differentiate PLGA from the more aggressive ACC would be extremely valuable but controversy exists in the current literature regarding their utility. This study examines the potential use of c-kit, Ki-67, smooth muscle actin (SMA), and muscle-specific actin (MSA) as ancillary markers for distinguishing PLGA from ACC. PATIENTS AND METHODS: Medical records of 20 cases of PLGA treated at the Massachusetts General Hospital were reviewed. Patient demographic data and tumor-specific information were elicited. Formalin-fixed paraffin-embedded sections from 10 of these cases and 12 comparison cases of ACC were accessed. The histologic diagnoses were confirmed and immunohistochemical staining using antibodies to c-kit, Ki-67, SMA, and MSA was employed to determine differences in staining. RESULTS: PLGA showed a significantly weaker immunohistochemical expression of c-kit compared with ACC (P = < .001). Ki-67, correlating with proliferative behavior, was more weakly expressed in PLGA (P = .091). The exuberant myoepithelial component of ACC resulted in stronger staining with SMA and MSA (P = .047; P = .065, respectively). CONCLUSIONS: Statistically significant immunohistochemical staining patterns using c-kit and SMA in this study support their potential use as markers to differentiate PLGA from ACC in cases where the diagnosis can be challenging.
PURPOSE: Polymorphous low-grade adenocarcinoma (PLGA) is a salivary gland malignancy characterized by indolent growth and a low rate of metastasis. PLGA shares histological features with adenoid cystic carcinoma (ACC), including infiltrating solid and cribriform patterns, presence of cystic spaces, and neurotropism. The degree of polymorphism of PLGA presents diagnostic challenges, particularly in small biopsy specimens. Immunohistochemical reactions to differentiate PLGA from the more aggressive ACC would be extremely valuable but controversy exists in the current literature regarding their utility. This study examines the potential use of c-kit, Ki-67, smooth muscle actin (SMA), and muscle-specific actin (MSA) as ancillary markers for distinguishing PLGA from ACC. PATIENTS AND METHODS: Medical records of 20 cases of PLGA treated at the Massachusetts General Hospital were reviewed. Patient demographic data and tumor-specific information were elicited. Formalin-fixed paraffin-embedded sections from 10 of these cases and 12 comparison cases of ACC were accessed. The histologic diagnoses were confirmed and immunohistochemical staining using antibodies to c-kit, Ki-67, SMA, and MSA was employed to determine differences in staining. RESULTS: PLGA showed a significantly weaker immunohistochemical expression of c-kit compared with ACC (P = < .001). Ki-67, correlating with proliferative behavior, was more weakly expressed in PLGA (P = .091). The exuberant myoepithelial component of ACC resulted in stronger staining with SMA and MSA (P = .047; P = .065, respectively). CONCLUSIONS: Statistically significant immunohistochemical staining patterns using c-kit and SMA in this study support their potential use as markers to differentiate PLGA from ACC in cases where the diagnosis can be challenging.
Authors: Brian D Adkins; Ariana Geromes; Lily Y Zhang; Rebecca Chernock; Katherine Kimmelshue; James Lewis; Kim Ely Journal: Head Neck Pathol Date: 2019-06-20
Authors: Stephan Schwarz; Maximilian Müller; Tobias Ettl; Philipp Stockmann; Johannes Zenk; Abbas Agaimy Journal: Int J Clin Exp Pathol Date: 2011-04-18
Authors: Justin A Bishop; Dipti P Sajed; Ilan Weinreb; Brendan C Dickson; Elizabeth A Bilodeau; Abbas Agaimy; Alessandro Franchi; Syed Ali Khurram; Philip Da Forno; Juliana Robledo; John R Kalmar; Sarah Aguirre; Jeffrey F Krane; Jose Luis Tapia; Katalin Kiss; Kitrina Cordell; Molly Rosebush; A William Barrett; Dolphine Oda; Adel Assaad; Toshitaka Nagao; Fumi Kawakami; Masato Nakaguro; Ismail Zahir; Kristina Wakeman; Stephan Ihrler; Jacinthe Chenevert; Yi-Ling Lin; William H Westra; Jeffrey Gagan; Lisa M Rooper Journal: Head Neck Pathol Date: 2021-05-12