Joen Iannucci Haring, DDS, MS
History
The patient stated that she first noticed the swelling on the left side of the hard palate approximately 11/2 years earlier. When questioned concerning any symptoms associated with the area, the patient described a vague discomfort that had been present for several months.
The patient characterized the discomfort as mild in severity. When further questioned, the patient denied any recent sinus infections, trauma, or tooth-related pain in the area.
At the time of the dental appointment, the patient`s medical history was reviewed. The patient reported a history of high blood pressure. No history of drug allergies was reported. The patient`s past dental history included sporadic dental examinations, routine extractions, and restorative dental treatment.
Examinations
The patient`s vital signs were all found to be within normal limits. Examination of the head and neck region revealed no enlarged or palpable lymph nodes. No significant or unusual findings were discovered during the extraoral examination.
Intraoral examination revealed a swelling on the left side of the hard palate. Palpation of the area revealed a firm, nonmovable, solid tumor mass that measured approximately 25 millimeters in diameter. The lesion was not painful when compressed. The teeth adjacent to the lesion were tested for vitality; all pulp tested vital. Further oral examination revealed no other lesions present.
Clinical diagnosis
Based on the clinical information available, which one of the following is the most likely diagnosis?
* maxillary torus
* necrotizing sialometaplasia
* pleomorphic adenoma
* adenoid cystic carcinoma
* polymorphous low-grade adenocarcinoma
Diagnosis
__ polymorphous low-grade adenocarcinoma
Discussion
Polymorphous low-grade adenocarcinoma (PLA) is a malignant salivary gland tumor. The term adenocarcinoma is used to describe a carcinoma derived from glandular tissue. (The word element adeno [Greek] means gland, while carcinoma refers to a malignant tumor made up of epithelial cells.) First described in 1983, PLA is only recently recognized as a malignant salivary gland tumor. Although PLA is one of the more common salivary gland malignancies, it is seen with less frequency than mucoepidermoid carcinoma and adenoid cystic carcinoma. The cause of PLA is unknown. However, tobacco use and radiation therapy are two identified risk factors that may be implicated in its tumorigenesis.
Clinical features
Polymorphous low-grade adenocarcinoma most often occurs in adults between the ages of 50 and 70. There is a strong female predilection. PLA develops almost exclusively within the minor salivary glands normally found on the hard and soft palates, upper lip, and buccal mucosa. More than 60 percent of cases involve the hard or soft palates, while 35 percent of cases involve the upper lip and buccal mucosa. The major salivary glands (parotid, submandibular, sublingual, for example) are rarely involved.
PLA typically presents as a firm, nonmovable, dome-shaped mass. The overlying mucosa may ulcerate, although ulceration is not common. The lesion has a history of slow growth and typically measures less than 3 centimeters in diameter. PLA may be painless or associated with mild discomfort and bleeding.
As the name low-grade suggests, PLA is a malignancy that is unlikely to cause death. Metastasis to the regional lymph nodes may occur but is uncommon. Distant metastasis is rare.
Diagnosis
The diagnosis of PLA is made based on biopsy and histologic appearance of the lesion. Other lesions that should be considered in the differential diagnosis include benign salivary gland tumors (pleomorphic adenoma, for example) and other malignant salivary gland tumors (mucoepidermoid carcinoma, adenoid cystic carcinoma, for example).
Treatment
The treatment for PLA is wide surgical excision. It is sometimes necessary to include a resection of the underlying bone. PLA recurs following surgical excision in approximately 25 percent of cases. Recurrence most likely occurs due to incomplete surgical removal. Treatment for recurrence includes re-excision. The prognosis for an individual with PLA is good, since 80 percent of cases are cured following adequate treatment.
Joen Iannucci Haring, DDS, MS, is an associate professor of clinical dentistry, Section of Primary Care, The Ohio State University College of Dentistry.
