COM October 2018 Diagnosis

Large well-demarcated swelling on the upper lip

Can you make the correct diagnosis?
This is a 21-year-old male who presented with a large smooth-surfaced, pink, firm and movable nodule on the upper lip.
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Case of the Month Summary

Canalicular adenoma

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A movable, firm, well-demarcated and slow-growing nodule of the upper lip should make one think of Canalicular adenoma since the upper lip is the most common site for that neoplasm. The age and gender in this case are not consistent with Canalicular adenoma. The histology is also not supportive of Canalicular adenoma.

Canalicular adenoma is a benign neoplasm that is almost exclusively of minor salivary gland origin. The upper lip is the most common location, accounting for over 80% of all cases. They present as well-circumscribed, firm, movable, slow-growing, painless nodules. They occur in females over the age of 50 and are usually single nodules. They are treated by simple enucleation.

Pleomorphic Adenoma (PA; Mixed Tumor)

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Although the age, gender and site (upper lip) in this case are not consistent with that of PA of the minor salivary tissue, the histology is that of PA. The slow-growth, firm and well-demarcated clinical presentation is also consistent with PA.

Pleomorphic adenoma is the most common benign salivary gland neoplasm of both the major and minor salivary glands. It originates from the myoepithelial cells and the reserve cells of the intercalated ducts. It accounts for 80% of all benign salivary gland neoplasms. It occurs in both major and minor salivary glands and accounts for up to 77% of parotid, 68% of submandibular, and 43% of minor salivary gland tumors. It is most common in females around 30-50 years of age, but it is also described in children but rarely. One study reports 1% of cases affecting children under 10 years of age and 5.9% between the ages of 10-20. Our patient fits in the latter group. PA presents as a small, painless, slowly enlarging nodule. If left untreated, it can enlarge significantly, sometimes increasing by several pounds in weight. It occurs in the oral cavity, especially in the posterior and lateral palate, as opposed to torus palatines, which usually occurs in the middle and anterior hard palate. The posterior hard palate mixed tumor is fixed due to the bone-bound anatomy of the region; the tumor is otherwise movable. Pleomorphic adenoma has a good prognosis, but it has a tendency for recurrence (up to 44%) if not treated thoroughly. The risk of recurrence is less if it occurs in the minor salivary glands (up to 20%).

Schwannoma (Neurilemmoma)

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A movable, firm nodule of the upper lip should make a clinician think of schwannoma since the lips are the third most common site for schwannoma of the peri-oral and oral cavity. The age in this case is on the age range for this neoplasm. The slow-growth and firm and well-demarcated clinical presentation is consistent with schwannoma but not the histology in this case.

Schwannoma is a benign, firm, smooth-surfaced, encapsulated and mobile neoplasm of Schwann cell origin. It occurs at any age but is more common in individuals 30-50 years of age with equal sex distribution. The tongue is the most common location, followed by the floor of mouth and the lips. It is also described within the jaw bones, especially the mandible. Up to 48% of schwannomas occur in the head-and-neck area. They are usually isolated lesions unless they present as part of neurofibromatosis type 1. Shwannoma presents as a slow-growing, firm, rubbery, smooth-surfaced nodule. Simple excision is the treatment of choice and recurrence is rare.

Leiomyoma

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A movable, firm nodule, slow-growing of the upper lip should make a clinician think of leiomyoma or angiomyoma (vascular leiomyoma). The age is on the younger age range but the gender in this case is consistent with leiomyoma. The histology, however, is not supportive of leiomyoma.

Leiomyoma is a benign neoplasm of smooth muscle origin. Uncommon in the oral cavity, it mainly occurs in the G.I. tract, uterus and skin. In the oral cavity, it most likely originates from the vascular smooth muscle. Vascular leiomyoma, also known as angiomyoma, accounts for 75% of oral leiomyomas. Patients tend to be over 30 years of age and are predominantly males. It is most common on the posterior tongue, palate, cheeks and lips. It is a slow growing, painless, pedunculated, smooth-surfaced, normal color or slightly bluish nodule. Intra-osseous leiomyomas have been reported, but very rarely. Simple and conservative excision is the treatment of choice.

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