Abstract
Objective:Adenoid cystic carcinoma and polymorphous adenocarcinoma are primarily the tumor of minor salivary glands. Both show certain morphological similarities, which limit their proper diagnosis in settings where there are obscuring factors and limited biopsy material. However, there is a considerable difference in treatment and prognosis, which raises the need to distinguish these two entities. In this study, we discuss the utility of two immunohistochemical stains, p63 and p40, in different combinations for distinguishing polymorphous adenocarcinoma from adenoid cystic carcinoma. Materials and Methods:Two immunohistochemical stains, p63 and p40, were performed on 47 cases of adenoid cystic carcinoma and 23 cases of polymorphous adenocarcinoma. Results:36 out of 47 cases of adenoid cystic carcinoma showed p63+ve/p40+ve immunoprofile, followed by p63-ve/p40-ve immunoprofile, which is seen in10 cases of adenoid cystic carcinoma. However, 22 out of 23 cases of polymorphous adenocarcinoma displayed p63+ve/p40-ve immunoprofile. p63-ve/p40+ve is the least frequent observed immunoprofile, which is seen in only one case of adenoid cystic carcinoma. Conclusion:On combining all possible immunoprofile combinations, p63+ve/p40-ve immunoprofile appears to be the most sensitive profile for distinguishing polymorphous adenocarcinoma from adenoid cystic carcinoma.
Highlights
Adenoid cystic carcinoma is one of the most common salivary gland malignancies, predominantly involving the minor salivary glands (Kokemueller et al, 2004; Dodd and Slevin, 2006)
We discuss the utility of two immunohistochemical stains, p63 and p40, in different combinations for distinguishing polymorphous adenocarcinoma from adenoid cystic carcinoma
22 out of 23 cases of polymorphous adenocarcinoma displayed p63+ve/ p40-ve immunoprofile. p63-ve/p40+ve is the least frequent observed immunoprofile, which is seen in only one case of adenoid cystic carcinoma
Summary
Adenoid cystic carcinoma is one of the most common salivary gland malignancies, predominantly involving the minor salivary glands (Kokemueller et al, 2004; Dodd and Slevin, 2006). Due to wide morphological spectrum of adenoid cystic carcinoma, it has numerous differential diagnosis, most common being polymorphous adenocarcinoma, previously known as polymorphous low-grade adenocarcinoma. It is imperative to reach an accurate diagnosis, as there is difference in the prognosis, treatment and follow up of these two entities. Distinction between adenoid cystic carcinoma and polymorphous adenocarcinoma remains a diagnostic challenge especially in small biopsies, sometimes requiring a battery of immunohistochemical stains for confirmation of diagnosis (Darling et al, 2002). Adenoid cystic carcinoma usually arises in the fifth and sixth decades of life with no gender predilection and has an unrelenting course of disease with multiple recurrences. The tumor has biphasic appearance, composed of basaloid appearing cells with angulated, hyperchromatic nuclei arranged in tubular, cribriform or solid patterns (Jaso and Malhotra, 2011)
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