Please cite this article in press as: Kolude B, et al. Strong immunohistochemical expression of C-kit may characterize adenoid cystic carcinoma of the salivary gland. J Oral Maxillofac Surg Med Pathol (2014), http://dx.doi.org/10.1016/j.ajoms.2013.11.008 ARTICLE IN PRESS G Model JOMSMP-246; No. of Pages 5 Journal of Oral and Maxillofacial Surgery, Medicine, and Pathology xxx (2014) xxx–xxx Contents lists available at ScienceDirect Journal of Oral and Maxillofacial Surgery, Medicine, and Pathology j o ur nal ho me pa ge: www.elsevier.com/locate/jomsmp Original Research Strong immunohistochemical expression of C-kit may characterize adenoid cystic carcinoma of the salivary gland Bamidele Kolude, Akinyele Olumuyiwa Adisa, Ahmed Oluwatoyin Lawal ∗ , Bukola Folasade Adeyemi University of Ibadan, Nigeria a r t i c l e i n f o Article history: Received 16 August 2013 Received in revised form 22 November 2013 Accepted 29 November 2013 Available online xxx Keywords: C-kit Adenoid cystic carcinoma Salivary gland tumors a b s t r a c t C-kit is a trans-membrane tyrosine kinase receptor detected in some malignant tumors but its expres- sion in salivary gland tumors (SGTs) is rather controversial, although affinity for adenoid cystic carcinoma (ACC) has been reported. Since C-kit is a target for the tyrosine kinase inhibitors, its use in treating malig- nant SGTs is needed as other therapeutic modalities have poor outcome. This study therefore investigated C-kit expression among subtypes of ACC and other SGTs. FFPE SGT sections were processed with antibody to C-kit using the specifications of the manufacturer (Polyclonal PA1-37375, Thermo-Scientific). Two investigators scored intensity of staining from negative to strongly positive. Data analysis was done using version 20 of SPSS. Qualitative data were compared using chi-squared statistics. Quantitative data were summarized using mean, standard deviation and compared using Student’s t-test and/or one-way analysis of variance. The level of significance was set at p < 0.05. Only ACC showed strong C-kit expression (38.5%) when compared to other C-kit positive SGTs and this was statistically significant (p = 0.03, Mann–Whitney U). There were however no significant differences in C-kit expression between the variants of ACC (p = 0.52, Mann–Whitney U). There was also a signif- icant difference in positive C-kit expression between the major and minor glands in MSGTs (p = 0.04, Mann–Whitney U). Strong expression of C-kit among MSGTs was exclusive in ACC and therefore may prove useful in resolving diagnostic challenges and for therapeutic intervention. © 2013 Asian AOMS, ASOMP, JSOP, JSOMS, JSOM, and JAMI. Published by Elsevier Ltd. All rights reserved.  1. Introduction C-kit (CD117) is a trans-membrane tyrosine kinase receptor that is required for normal hematopoiesis, melanogenesis and gameto- genesis. Expectedly, C-kit expression has been detected in chronic myelogenous leukemia (CML), malignant melanomas and semi- nomas but it has also been expressed in gastrointestinal stromal tumors (GISTs) and salivary gland tumors (SGTs) especially ade- noid cystic carcinoma (ACC) [1–4]. The gain of functional mutation is the basis of C-kit overexpression in GIST and seminomas, how- ever, among SGTs this is rarely reported and highly controversial  AsianAOMS: Asian Association of Oral and Maxillofacial Surgeons; ASOMP: Asian Society of Oral and Maxillofacial Pathology; JSOP: Japanese Society of Oral Pathol- ogy; JSOMS: Japanese Society of Oral and Maxillofacial Surgeons; JSOM: Japanese Society of Oral Medicine; JAMI: Japanese Academy of Maxillofacial Implants. ∗ Corresponding author at: Department of Oral Pathology, University of Ibadan, Nigeria. Tel.: +234 8055133964; fax: +234 22411768. E-mail addresses: lawaloluwatoyin@gmail.com, toytoy219@yahoo.com (A.O. Lawal). [5]. C-kit is a target for the tyrosine kinase inhibitor imatinib mesy- late (Gleevec) that has had significant therapeutic responses in CML and advanced C-kit positive GIST [6,7]. Targeted molecular therapy is also desirable for malignant sali- vary gland tumors (MSGTs) as the existing combination of surgery, radiotherapy and chemotherapy has resulted in poor success rates of 15–50% for recurrent and advanced cases [8,9]. ACC and polymor- phous low-grade adenocarcinoma (PLGA) have similar precursor cells and histomorphology [10,11]. Hence, histological differen- tiation may pose a significant challenge, especially with small biopsies. It is necessary to distinguish between these two lesions because ACC is more aggressive and infiltrative than PLGA [12,13]. Previous studies on the expression of C-kit among SGTs were focused mostly on the expression of C-kit among the subtypes of ACC or the role of C-kit in distinguishing between ACC, PLGA and other types of SGTs [12,14,15]. The level of expression among the subtypes of ACC is highly conflicting with some authors reporting higher expression among the well differentiated cribriform and tubular subtypes while oth- ers reported higher expression among the poorly differentiated 2212-5558/$ – see front matter © 2013 Asian AOMS, ASOMP, JSOP, JSOMS, JSOM, and JAMI. Published by Elsevier Ltd. All rights reserved.  http://dx.doi.org/10.1016/j.ajoms.2013.11.008