COM Feb. 2014 Diagnosis

Large & Ulcerated Swelling on the Posterior/Lateral Palate

Can you make the correct diagnosis?

This is a 52-year-old male who presented with a swelling “lump” on the posterior/lateral junction of hard and soft palate, present for many years.

1. Carcinoma ex pleomorphic adenoma

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A swelling in the palate other than torus palatinus (TP) should always bring to mind salivary gland neoplasms. While TP is present in the middle to anterior hard palate, salivary gland neoplasms are usually present in the posterior/lateral hard palate, junction of hard and soft plate and soft palate. This lesion fits the clinical presentation. The clinical history of twenty years’ presence supports a diagnosis of a pleomorphic adenoma (MT) while the clinical history of recent changes, symptoms and ulceration also consistent with carcinoma ex pleomorphic adenoma. For all these reasons, this condition is the most likely for this clinical presentation. The histology, however, is not supportive of this diagnosis.

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 30-50 years of age, but it is also rarely described in children. One study reports 1% of cases affecting children under 10 years of age and 5.9% between the ages of 10-20. It 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 the palate and lips. On the palate, it is usually located in the posterior hard palate or anterior soft palate but can also be in the posterior soft palate; PA usually occurs in the posterior and lateral palate, as opposed to torus palatinus, which usually occurs in the middle hard palate and in the anterior. The posterior hard palate mixed tumor is fixed due to the bone-bound anatomy of the region; the tumor is otherwise movable. Histologically, mixed tumor has a wide variety of cellular and pattern manifestations; the main cellular components are epithelial duct-like structures and mesenchymal-like tissue such as myxochondroid matrix. These lesions are generally encapsulated, ranging from predominantly myxoid (36%) to extremely cellular (12%). Complete surgical removal with clean margins is the preferred treatment. Palatal lesions respond well to excision in one piece with the periosteum and overlying mucosa. 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%). The risk of malignant transformation is about 5%.

2. Mucoepidermoid Carcinoma

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As stated before, a non-bony swelling in the posterior lateral palate of 20 years’ duration is an unlikely presentation for a malignant neoplasm. However, low-grade mucoepidermoid carcinomas can take years to develop and, for that reason, it should be considered on the differential diagnosis (though a mucoepidermoid carcinoma typically would not take as many as 20 years to develop). The spontaneous ulceration is also consistent with MEC. The histology is not supportive of this diagnosis.

Mucoepidermoid carcinoma is a malignant neoplasm of salivary gland origin that can present as a smooth-surfaced swelling or a non-healing ulcer on the palate, usually the posterior lateral palate. It occurs in a wide age range and has three histologic types: low, intermediate and high; the low-grade type is more common in the oral cavity. Mucoepidermoid carcinoma accounts for 10% of all salivary gland neoplasms. While the majority of MECs occur in the parotid gland, some also occur in minor salivary glands, especially the palate, tongue, buccal mucosa, lips, and retromolar pad areas. It can occur at any age with a predilection for occurrence in young people. Studies by the Armed Forces Institute of Pathology (AFIP) find 44% of cases occurring in patients under 20 years of age, most commonly on the palate. Their youngest patient was nine months old. The low-grade lesions are slow-growing and painless, and not encapsulated; they sometimes resemble a mucocele, especially those at the retromolar pad area. Mucoceles of the retromolar pad area are rare, and for that reason it is best to biopsy them early to exclude the possibility of a mucoepidermoid carcinoma masquerading as a mucocele. High-grade lesions tend to be more common in the parotid gland; they present as rapidly growing, painful lesions with facial nerve paralysis and sometimes with regional lymph node metastasis. Histologically, mucoepidermoid carcinomas consist of a variety of cell types and architectural patterns which constitute the three histologic gradings. Although low-grade mucoepidermoid carcinoma is characterized by an abundance of mucous-producing cells and duct-like structures with cystic dilation, the mere presence of certain types of cells and architecture should not be used to determine the histologic grade. Complete surgical removal with clean margins is the preferred treatment for the low-grade type. Radiation therapy has also been successfully used, especially when the tumor involves the surgical margins.

3. Adenoid Cystic Carcinoma

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The site of the lesion, the rolled border, the bluntly papillary surface are all consistent with the presentation of a chronic granulomatous type of condition be it infectious or of other etiology. The duration of two years is not supportive of an infectious condition but can be a foreign body granuloma type of granulomatous process. The histology was not supportive of infectious or other granulomatous processes.

Some infections of the oral cavity, especially the deep granulomatous type of infectious diseases, may present as diffuse, deep ulcers with rolled borders on the lateral ventral tongue comparable to the clinical presentation of malignant neoplasms such as squamous cell carcinoma.

The oral cavity is a site where a number of acute and chronic infectious diseases occur as a local primary disease or as a manifestation of a systemic disease. They include diseases of viral, fungal and bacterial origin. They usually present in multiples or in a diffuse manner ranging from ulcers to small and nodular lesions to verrucoid lesions. Occasionally, granulomatous-type infectious diseases present as diffuse and deeply ulcerative lesions with rolled borders, simulating oral SCC. These cases include ulceration induced by mycobacterium tuberculosis, deep fungal infections such as blastomycosis and Histoplasmosis, and chancre of primary syphilis. Oral manifestations of tuberculosis and Histoplasmosis are unusual without lung involvement and a disseminated disease; they occur more often in immune-compromised patients. The gingiva and the mandibular vestibule are more common locations, but the tongue can occasionally be affected. Chancre can occur in any location, including the tongue, lips and hard palate.

4. Epithelial-Myoepithelial Carcinoma

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Epithelial-myoepithelial carcinomas are rare salivary gland neoplasms (SGNs). They constitute fewer than 1% of SGNs. They are low-grade and slow-growing. One case was described to be slowly growing over a three year period. However, a 20-year presence is not reported. This neoplasm was first described by Donath et al in 1972 and later clarified by Corio et al in 1982. They are of intercalated duct origin. The parotid gland is the most common location for this neoplasm, accounting for 80% of the cases, followed by the submandibular gland and minor salivary gland tissue. The latter include those in the buccal mucosa, palate, larynx, lacrimal glands, nose, maxillary sinus and the lungs. The clinical signs and symptoms include swelling, pain and facial nerve weakness. It is very rare for this neoplasm to affect the sublingual gland.

In about 60% of cases, this neoplasm occurs in females. The age range is 31-89 with an average of 61.5 years of age. It is very rare in children but has been described in the parotid gland of an 8-year old boy from Japan. Histologically, the tumor is usually well demarcated and can be partially encapsulated. It is usually multinodular but can be one large nodule or can have a cystic area. It is biphasic in that it has two cell populations arranged in two layers surrounding the lumen of the ducts. The inner layer is composed of columnar or cuboidal cells with abundant cytoplasm surrounded by an outer layer, also composed of cuboidal or columnar cells with pale or clear cytoplasm. The latter cells are consistent with the morphology of myoepithelial cells. The pattern of invasion is in form of islands and nests. The epithelial cells are well-differentiated with rare nuclear atypia. Mitosis and necrosis are not common.

The treatment of choice is wide surgical excision. This neoplasm has a high recurrence rate and low chance of metastasis. On the average, 30-50% of EMC recur in a five-year period, some with multiple recurrences. Metastasis to regional lymph nodes is 18% and to distant organs such as the lungs is 8-10%. A few cases have been documented to recur between 9 and 28 years after the first diagnosis. The overall five-year survival rate is 87% and the ten-year survival rate is 67.5%.

5. Others

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Soft tissue neoplasms such as neurofibromas should be considered on the differential diagnosis. The histology however, is not consistent with any soft tissue neoplasms.