Lip pleomorphic adenomas: case series and literature review

Abstract

Background: Pleomorphic adenoma (PA) is the most frequent benign salivary gland tumor, but a lip PA is rare. Although this tumor may be definitively diagnosed by imaging or a tissue biopsy if it is reasonably large, PAs on the lip are relatively small, and they present findings that are similar to those of other lip lesions, which can make a preoperative diagnosis difficult. Methods:We analyzed all PAs in the oral region and lesions on the lips treated in our department over the past 20 years, and we discuss them together with the relevant literature.Results: We found that 11.8% (n=6) of the PAs occurred on a lip (upper lip: 9.8%, lower lip: 2.0%), and ~1% of all mass lesions of the lips were PAs. The average size of the lip PAs was 1.5±0.7 cm (range, 0.7-2.2 cm).For preoperative diagnostic assistance, ultrasonography (US) (n=4), magnetic resonance (MR) (n=3), or no imaging (n=2) was used. An excisional biopsy was performed in all cases, and to date, no recurrence or malignant transformation has been observed.Conclusions: Lip PA is relatively rare. Because almost all of these lesions are small, a preoperative diagnosis is more difficult compared to palatal lesions. This tumor is also prone to long-term neglect and has the potential for recurrence and malignant transformation. It is thus necessary to perform an excision that includes the capsule and surrounding tissues, and careful postoperative follow-up should be continued.

Ultrasonographic features of mass lesions in the oral submucosal epithelium using intraoral ultrasonography

“…In our study, the thick, collagenous capsule observed in the histopathological image corresponded to the single hypoechoic layer surrounding the mass in the ultrasonographic image, and the tubular or cyst‐like glandular lumen inside the tumor in the histopathological image corresponded to the circular hypoechoic area in the center of the mass in the ultrasonographic image (Figure 6). Ultrasonographic findings of pleomorphic adenoma have been reported with single layer of hypoechoic images at the margins of the lesion 18,31 . Because the ultrasonographic images of all cases showed a single layer of hypoechoic image at the margins in our study, one of the characteristics of ultrasonographic findings in pleomorphic adenoma is that the capsular structures seen in the histopathology are depicted as hypoechoic images at the margins of the lesion.…”

“…Ultrasonographic findings of pleomorphic adenoma have been reported with single layer of hypoechoic images at the margins of the lesion. 18,31 Because the ultrasonographic images of all cases showed a single layer of hypoechoic image at the margins in our study, one of the characteristics of ultrasonographic findings in pleomorphic adenoma is that the capsular structures seen in the histopathology are depicted as hypoechoic images at the margins of the lesion. Some cases may present a cyst-like hypoechoic image inside the lesion, 18 and this finding is one of the differential diagnoses, which was observed in two out of five of our cases.…”

Pleomorphic adenoma (mixed tumor) of the upper lip: A case report

“…PA on the lip is more common in the upper lip than in the lower lip with a ratio of 6:1[ 7 , 10 ]. However, this tends to vary with centers where the report comes from[ 8 , 11 , 12 ]. Umemori et al [ 12 ] found that 11.8% of the PAs occurred on the lips, of which 9.8% were distributed on the upper lip and 2.0% on the lower lip.…”

“…However, this tends to vary with centers where the report comes from[ 8 , 11 , 12 ]. Umemori et al [ 12 ] found that 11.8% of the PAs occurred on the lips, of which 9.8% were distributed on the upper lip and 2.0% on the lower lip. For preoperative diagnostic assistance, ultrasonography and magnetic resonance are useful.…”

“…Our case was extraoral on the upper lip, similar to the one described by Gelidan and Arab[ 8 ]. The clinical differential diagnosis of swelling of the lips is inclusive of cystic diseases (mucocele, dermoid cyst, and epidermoid cyst), benign tumors (fibroma, hemangioma, lipoma, and schwannoma) and malignant tumors (squamous cell carcinoma, mucoepidermoid carcinoma, and adenoid cystic carcinoma), foreign body, infection, orofacial granulomatosis, Quincke’s edema, tuberculosis, and actinomycosis[ 12 ]. Complete wide surgical excision is the treatment of choice to minimize recurrence and possible malignant transformation, such as carcinoma ex PA, should the lesions be left unattended for a long time.…”