Short Communication Polymorphous adenocarcinoma transforming to Adenoid cystic carcinoma - A case report A.K. Anjali a , Sandhya Tamgadge a , Treville Pereira a, * , Rutuja G. Vidhale a , S. Sudhamani b a Department of Oral Pathology, D.Y.Patil Dental College, D.Y.Patil University, India b Department of General Pathology, D.Y.Patil MedicalCollege, D.Y.Patil University, India ARTICLE INFO Keywords: Adenoid cystic carcinoma Immunohistochemical staining Polymorphous adenocarcinoma ABSTRACT Polymorphous adenocarcinoma is an indolent salivary gland carcinoma characterized by cytologic uniformity and architectural diversity, predominantly affecting minor salivary glands, in particular the hard and soft palate. Adenoid cystic carcinoma (ACC) is an uncommon type of adenocarcinoma, a kind of malignant growth that starts in glandular tissues. It most regularly emerges in the major and minor salivary organs of the head and neck. This paper reports an instance of a 59-year-old male patient who was determined to have Polymorphous adenocar- cinoma which ultimately ended up being Adenoid cystic carcinoma. 1. Introduction Salivary gland tumors are a group of diverse lesions with rare and variant morphogenetic features. Polymorphous adenocarcinoma is one such variant characterised with cytologic uniformity and architectural diversity predominantly affecting the minor salivary glands. This article discusses one such case wherein the histopathological examination and Immunohistochemical (IHC) investigation resulted in a contrasting diagnosis. 2. Case report A 59-year-old male patient complained of painless swelling on the left side of the face for 6 months (Fig. 1) The swelling was small in size which eventually grew in size measuring about 10x8x5cm. The patient had a history of cigarette smoking 5 to 7 times per day for 35–40 years. The histopathological diagnosis was given as Polymorphous low-grade Adenocarcinoma (PLGA) (Figs. 2, 3 Fig. 4). IHC was performed for further validation of the diagnosis using different markers namely Ki67, p40, CD117, EMA (Figs. 5–8). 3. Discussion The new term Polymorphous Low-Grade Adenocarcinoma (PLGA) was coined in 1984 by Evans and Batsakis et al. [1]. However, it is very rare for PAC to show high grade transformation, in this case there is a marked transformation seen [2]. The tumor stroma consists of both mucus and hyaline areas where the tumor cells are arranged in various morphological patterns such as solid, cribriform, duct- like, papillary and tubular patterns including morpho diversity and are separated by fibro- vascular stroma. Nonetheless, IHC staining for PAC showed negative for myoepithelial markers such as alpha-SMA and p40 showed diffuse pos- itivity for PAC whereas it does not stain ACC [3,4]. C-kit protein marker or CD117 is a transmembrane tyrosine kinase growth factor receptor having its role in diagnosing ACC along with clinical findings as evalu- ated by Lee et al., which showed no predictive value for prognosis and recurrence. In this study, we have explored the expression of CD117 in ACC and PLGA. Despite affecting the differentiation and function of mast cells, hematopoietic progenitor cells, germ cells, and melanocytes through its interaction with the c-kit receptor, CD117 have not shown any direct relation with the pathogenesis of ACC [5]. In the current study, we have encountered all the three patterns of ACC which showed strong diffuse cytoplasmic staining when compared to PLGA which showed weak cytoplasmic staining. Adding to this, p40 immunohistostaining showed negative for ACC also correlating to the fact that PLGA has a consistent p40 immunophenotype thus making it a diagnostic tool in differentiating the two [6]. 4. Conclusion In the above study we examined the tumor which was diagnosed as PAC using histopathological examination. However, with further inves- tigation using IHC it revealed a transition from the previous diagnosis, * Corresponding author. E-mail addresses: anju.innova@gmail.com (A.K. Anjali), sandhya.tamgadge@ gmail.com (S. Tamgadge), trevillepereira@gmail.com (T. Pereira), rutuja. vidhale@gmail.com (R.G. Vidhale), dr.sudhamani@gmail.com (S. Sudhamani). Contents lists available at ScienceDirect Advances in Oral and Maxillofacial Surgery journal homepage: www.editorialmanager.com/adoms/default.aspx https://doi.org/10.1016/j.adoms.2021.100079 Received 25 March 2021; Accepted 15 April 2021 Available online 19 April 2021 2667-1476/© 2021 The Authors. Published by Elsevier Ltd on behalf of British Association of Oral and Maxillofacial Surgeons. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/). Advances in Oral and Maxillofacial Surgery 3 (2021) 100079