Mucosa of the oral cavity and lips shares a lot of histologic features with the skin. Inflammatory and neoplastic conditions are almost identical in both tissues. However, the oral cavity is subject to a different microenvironment and attains more functions that predisposes it to distinct patterns of diseases [4]. In addition, odontogenic and salivary gland lesions arise in the oral cavity but not skin. They are diverse and represent a significant fraction of pathology specimens there.
The recent advancement in medical sciences changed the trends of clinical practices in the last decades. Oral lesions were often treated empirically and surgical biopsies were done by general dentists. Currently, oral biopsies are routinely taken for diagnostic pathology which is reflected by the increasing number of referred specimens annually [5]. In certain situations, the procedure is performed by more specialized practitioners such as oral pathologists, maxillofacial, head and neck, ENT and plastic surgeons. All of these factors enhanced reaching accurate diagnoses and provided a better patient care. Thus, the practice of oral pathology requires well-knowledgeable and experienced pathologists.
In this study, inflammatory diseases were the most common group, slightly outnumbering benign neoplasms. A similar finding was reported in many previous studies [2, 6–9], while in some, benign neoplasms were more common [10, 11]. Interestingly, oral lichen planus was the most common inflammatory condition in this study (18%) exceeding what was reported in Turkey (11.9%) and Kuwait (4.6%) [6, 12]. Lichen planus is an inflammatory mucocutaneous disease of unknown etiology and its epidemiology varies between 1-3% among populations [13]. The disease is associated with diabetes [14]. A similar condition, called lichenoid reaction, occurs secondary to an obvious factor, such as drug exposure. The high frequency of lichen planus in our study could be attributed to the high prevalence of diabetes which affects 16% of Jordanian population [15]. In addition, we combined both lichen planus and lichenoid reaction is the same category due to incomplete medical history in many cases. Yet, the accurate explanation mandates a focused study in the future.
Odontogenic cysts are heterogenous diseases that arise from odontogenic epithelium [3]. Similar to our study, radicular cyst was the most common odontogenic cyst, followed by dentigerous then Keratocyst [16–20]. Radicular cyst typically complicates inflammatory conditions such as trauma or dental caries, while dentigerous cyst is a developmental anomaly and is associated with unerupted tooth. In contrast, keratocyst is a neoplastic disorder but it is still classified under the umbrella of odontogenic cysts in the World Health Organization classification system [3]. Both radicular and keratocysts can affect any age-group, but the peak incidence is in the fourth-fifth decade and the third decade, respectively [3, 21–22]. A peculiar finding in our study is that the overall incidence of odontogenic cysts peaked at younger age-groups, and the frequency of radicular cyst was more common in children than in adult. Similarly, the mean age of keratocyst was 27 years, which was -again- younger than what was described previously [22].
Squamous papilloma and pyogenic granuloma equally predominated benign tumors in our study and appeared in a wide range of age. Squamous papilloma carried different names in previous studies such as fibroepithelial polyp or fibroepithelial hyperplasia was consistently very common, while pyogenic granuloma exhibited a variable frequency from high and low [2, 6, 9, 12]. It is noteworthy to mention that Human Papilloma Virus-related proliferation, which may mimic squamous papilloma, were not encountered. Salivary gland tumors and odontogenic tumors were less common, and the vast majority of cases were of pleomorphic adenoma and ameloblastoma, respectively. Benign soft tissue tumors very rarely occurred.
A few previous studies showed that cancer was the most common finding is oral specimens [1, 4, 18, 23–24]. Malignant tumors constituted 10% of specimens in our series, which is close to what was reported in Libya (8%), UAE (14.9%) and Iraq (14.5%) but higher than Kuwait (3.6%), Spain (3.9%) and UK (5.4%) [6, 23–26]. In contrast, a few studies showed that malignancy was the dominant disease among oral biopsies [27, 28]. SCC represented, by far, the most common oral cancer in our and all previous reports. It is known to be strongly associated with certain environmental factors and personal habits such as smoking, tobacco chewing and poor oral hygiene. This explains the high prevalence of SCC and thus high frequency of malignant lesions in oral biopsy in some geographic areas such as India and Southwest Saudi Arabia. According to this study, the Jordanian population falls within the low-frequency of oral cancers, most of which is SCC, while primary salivary gland carcinoma and lymphoma are uncommon.
Intraoral, minor salivary glands tumors, are relatively uncommon accounting for 25% of all salivary gland tumors. In contrast to large salivary glands, tumors of minor salivary glands show a higher rate of malignancy reaching approximately half of cases [29]. In previous reports, pleomorphic adenoma was consistently the most common benign tumor, while the most common malignancy was either mucoepidermoid and adenoid cystic carcinomas. Our study shows a relatively lower percentage of malignancy in minor salivary glands, and the most common type was acinic cell carcinoma.