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Canalicular adenoma of the upper lip
Metachronous (multifocal) canalicular adenoma of the upper lip: a case report of an unusual finding

Introduction

Canalicular adenoma (CA) is a distinctive tumor occurring almost exclusively in the upper lip [1-3]. It is a relatively rare neoplasm, but it is the second (or the third) most common tumor among benign tumors of minor salivary glands [4, 5]. A few cases of multiple foci of CA have been reported in the literature [6-12]. We present herein a new case of multifocal canalicular adenoma of the upper lip, involving a 57-year-old woman, and discuss histological and immunohistochemical characteristics of the tumor.

Case report

A 57-year-old female patient presented to the Dentistry Department with a tumor on the upper lip. Macroscopic examination revealed a well-circumscribed, smooth, firm, round nodule with a diameter of 0.5 cm (Fig. 1). Histologically, it was composed of anastomosing duct-like or trabecular structures lined with a single or double layer of columnar cells (Fig. 2), which were immunoreactive to cytokeratin (Fig. 3), CD117 (Fig. 4) and S100 protein (Fig. 5). The histological texture and immunohistochemical characteristics of primary tumor, localized in the neighborhood, excised 2 years earlier, were similar to the microscopic picture of the presented neoplasm. The patient is currently free of disease 6 months after surgical excision of the tumor.

Discussion

Canalicular adenoma is a benign tumor which comprises 1% of salivary gland neoplasms. However, among intraoral minor salivary gland tumors it constitutes approximately 5.6%-11.7% of all studied cases [4, 5, 13-15].

It occurs typically (in about 90% of cases) in the upper lip [1-3] and buccal mucosa [13] of individuals usually over 60 years old. Infrequently it is found on the palate [16, 17] and in the parotid gland [8, 18, 19].

A few cases of multiple foci of CA have been reported in the literature. Most of them appeared as synchronous, sometimes bilateral changes (Table 1). The exceptionally rare multifocal cases were presented by Rousseau [10] and by Khullar et al. [12]. The first author described a case that manifested with 13 clinically discrete tumor masses involving the upper lip and anterior buccal mucosa. In addition to the clinical nodules, there were microscopic foci of tumor cells in the adjacent normal-appearing salivary gland tissue surrounding the tumors [10]. Khullar et al. presented a patient who had multiple canalicular adenomas in the upper lip and adjacent oral mucosa. A few months after these had been excised,...


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