Oral Pathology
Posted by John Doe at Dental Assistant on February 18, 2012.
Categories: Dental Secrets
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Fibroosseous Tumors
95. Ossifying fibromas arise from bone-producing ce lls, and cementifying fibromas are odontogenic in origin. True or false?
In real life and real pathology, the line of demarcation between the two is not so clear. They are clinically indistinguishable. Histologically, although pure ossifying a nd pure cementifying fibromas exist, it is much more common to see a mixture of bone/osteoid and cementum in any given lesion, with either predominating or in equal proportions. Many pathologists use the term cementoossifying fibroma as a unifying concept. The cell of origin is likely to be a mesenchymal cell in the periodontal ligament that is capable of producing either bone or cementum, therefore duplicating the two anchoring sites for Sharpey's fibers. From that point of view, both are odontogenic in origin.
Central cementoossifying fibroma with round globules of cementum and trabeculae of osteoid.
96. Is it possible to distinguish histologically between fibrous dysplasia and c entral ossifying tThroma?
No. The clinical and radiographic findings are the most important for differentiating between the two. Fibrous dysplasia tends to occur in the maxilla of young people and presents as a poorly defined radiolucent or radiopaque area th at is nonencapsulated. The radiographic appearance has been described as "ground glass." The central ossifying fibroma is a well-demarcated radiolucency, often with a distinct border, and may contain areas of radiopacity within the lesion. It is more common in the mandible.
Soft Tissue Tumors
97. Fibroma of the oral cavity is a true neoplasm. True or false?
It depends on your definition of neoplasm. As its name suggests, fibroma of the oral cavity is a tumor ("-oma") composed of fibrous tissue. It tends to occur as a result of trauma and therefore usually presents on the buccal mucosa, lower labial mucosa, and lateral tongue. It is nonencapsulated and grows as long as the inciting factor, such as trauma, is present. By Willis's definition of neoplasm ("new growth"), the growth, once established, continues in an excessive manner even after cessation of the stimuli that first evoked the change. Some pathologists, therefore, prefer the term fibrous hyperplasia rather than fibroma because it more accurately reflects its nature. The pathogenesis is similar to that of fibrous hyperplasias caused by poorly fitting dentures.
Fibroma of tongue.
98. What are verocay bodies?
Vero cay bodies consist of amorphous-looking, eosinophilic material that forms between parallel groups of nuclei in the schw annoma. They actually represent duplicated basement membrane produced by Schwann cells and are an important component of Antoni A tissue.
99. What is the cell of origin of the g ranular cell tumor? How is it different from the cell of origin of the congenital epulis of the newborn?
The ce ll of origin of the granular cell tumor is probably a neural cell, such as th e Schwann cell. This tumor used to be called the granular cell myoblastoma because it was believed that the cell of origin was a m yocyte. The cell appears granu lar because it contains many lysosomes. By light microscopy, these cells resemble cells of the congenital epulis of the newborn. Whereas the granular cell tu mor stains for S-lOO protein, a marker for neural tissues, among others, the congenital epulis does not.
100 . A patient presents with multiple neuromas of the lips and tongue. What do you suspect?
The patient probably has multiple endocrine neoplasia type III, which is inherited as an autosomal dominant condition. Patients also have pheochromocytomas, café-au-lait macules, neurofibromas of the skin, and medullary carcinoma of the thyroid. Recognition of the oral findings may lead to early diagnosis of the thyroid carcinoma.
101. What are venous lakes?
Venous lakes are purplish-blue nodules or papules, often present on the lips of older people, that represent dilated venules or varices.
102. What is the most common benign salivary gland tumor?
Pleomorphic adenoma.
103 . Why is pleomorphic adenoma sometimes called the benign "mixed tumor"?
Pleomorphic adenoma is called a "mixed tumor" because histologically it may have a mixture of both epithelial and connective tissue components, although in fact it is an epithelially derived tumor. The connective tissue components may be prominent beca use one of the cells responsible for the tumor is the myoep ithelial cell, which, as its name suggests, has properties of both epithelial and connective tissue. This cell is responsible for the areas of cartilage and bone formation as well as for the myxoid nature of many "mixed tu mors." In addition, th ere are areas of epithelial cell proliferation in the form of ducts, islands, and sheets of cells.
104 . What is the brown tumor?
The br own tumor is histologically a central giant-cell granuloma associated with h yperparathyroidism. It appears brown when excised because it is a highly vascular lesion. Bec ause it is indistinguishable from banal central giant-cell granuloma, all patients diagnosed with central giant-cell granuloma should have th eir calcium levels checked.
MALIGNANT NEOPLASMS
105. What percentage of the population has leukoplakia? What percentage of leukoplakias have dysplasia or carcinoma when first biopsied compared with erythroplakias?
Leukoplakia occurs in 3-4% of the population, and 15-20% of leukoplakias have dysplasia or carcinoma at the time of biopsy, whereas 90% of erythroplakias show such changes at the time of biopsy.
Squamous cell carcinoma presenting as leukoplakia with erythematous and verrucous areas.
106. What is proliferative verrucous leukoplakia?
It is a clinically aggressive and progressive form of leukoplakia with a higher rate of malignant transformation than banal leukoplakia.
107. What is the prevalence of oral cancer in the United States? Which country in the world has the highest prevalence of oral cancer?
Oral cancer accounts for 3-5% of all cancers in the United States if one includes oropharyngeal lesions. India has the highes t prevalence of oral cancer, which is the most common cancer in that country and is related to the use of betel nut and tobacco products.
108. What are the risk factors for oral cancer?
- Tobacco products
- Alcohol (especially in conjunction with smoking)
- Betel nut products (especially in East Indians and some Southeast Asian cultures)
- Sunlight (especially for cancer of the lip in men)
- History of syphilitic glositisrs
- History of submucous fibrosis
- Immunosuppression
- History of oral cancer or other cancer
- Preexisting oral mucosal dysplasia
- Age
109. What do snuff-associated lesions look like?
At the site where the snuff is placed (usually the sulcus), the mucosa is whitened with a translucent hue, and linear white ridges run parallel to the sulcus.
110. What is the difference in prognosis between a squamous cell carcinoma and a verrucous carcinoma?
Approximatel y one-half of squamous cell carcinomas hav e metastasized at th e time of diagnosis. The larger they are, the more likely that metastases will develop. Verrucous carcinomas do not tend to metastasize d espite the rather large size o f some lesions. They are locally aggressive lesions. Whereas many squ amous cell ca rcinomas are radiosensitive, verrucous carcinomas have been reported to become extremely aggressive and histologically anaplastic when treated with radiation
111 . What is a "rodent ulcer"?
A rodent ulcer refers to a basal cell carcinoma that, despite its low tendency to metastasize, erodes through adjacent tissues like the gnawing of a rodent and through persistence may cause destruction of the facial complex.
112. What are the three most common intraoral malignant salivary gland tumors?
Mucoepidermoid carcinoma, polymorphous low-grade adenocarcinoma, and adenoid cystic carcinoma. The polymorphous low-grade adenocarcinoma also has been reported under the names of terminal duct carcinoma and lobular carcinoma.
113. Which two salivary gland t umors often show perinuclear invasion (neurotropism)?
Adenoid cystic carcinoma and polymorphous low-grade aden ocarcinoma. However, any malignancy (particularly carcinomas) can show perinuclear invasion that may represent invasion of the lymphatics around a nerve.
114. The benign lymphoepithelial lesion of Sjögren's syndrome is an in nocuous autoimmune sialadenitis. True or false?
False. The "benign" lymphoepithelial lesion is not so benig n. Many experts belie ve that these lesions are premalignant. Affected patients have a higher incidence of lymphoma than the general population.
115. A patient with Sjogren's syndrome is referred for a labial salivary gland biopsy to identify a benign lymphoepithelial lesion. Does thi s sound right?
No. The benign lymphoepithelial lesion of Sjogren's syndrome is fou.u d in th e major glands, mainly the parotid, especially if parotid enlargement is present. A labial salivary gland biopsy will show an autoimmune sialadenitis characterized by lymphocytic infilt rates that form foci. The more foci, the more likely the diagno sis of an autoimmune sialadenitis; foci are less specific than the lymph oepithelial lesion.
116. Do lymphomas of the oral cavity occur outside Waldeyer's ring?
Yes. Oral lymph omas are most common in Waldeyer's ring, but they may occu r in the palate (a condition formerly described as lymphoproliferative disease of the palate), buccal mucosa, tongue, floor of the mouth, and retromolar areas. Not infrequently they are also primary lesions in the jaw bones.
117. What does a monoclonal plas ma cell proliferation mean?
Plasma cells produce immunoglobulin that contains heavy and light chains. Each plasma cell and it s progeny produce either kappa or lambda light chains. A group of plasma cells that produces only kappa or lambda light chains but not both is most likely due to a proliferation of a single malignant clone of plasma cells, such as a plasmacytoma or multiple myeloma. The presence of both light chains in a plasma cell proliferation is more in keeping with a polyclonal proliferation, which characterizes inflammatory lesions.
118. Name the different epidemiologic forms of Kaposi's sarcoma.
- Classic r European form: usually Eastern European men (often Jewish); multiple red papules on the lo extremities, with rare visceral involvement and a more indolent course.
- Endemic or African form: young men or children in equatorial Africa; frequent visceral involvement that may be fulminant.
- Epidemic form: HIV-associated; may be widely disseminated to mucocutaneous and visceral sites; variable course.
- Renal transplant-associated form: patients who have undergone renal transplantation with immunosuppressive therapy; lesions usually regress wh enimmunosuppressive therapy is discontinued.
119. A patient has a suspected metastatic tumor to the mandible. What are the likely primary tumors?
- Lung • Prostate • Gastointestinal tract • Thyroid
- Breast • Kidney • Skin
120. Osteosarcoma of the jaws occurs in younger patients more often than osteosarcoma of the long bones. True or false?
False. Patients with osteosarcoma of the jaws are 1-2 decades older than patients with osteosarcoma of the long bones.
121. What conditions predispose to osteosarcoma? Many cases of osteosarcoma in young adults occur de novo. However, there are well-documented cases of osteosarcoma in association with Paget's disease, chronic osteomyelitis, a history of retinoblastoma, and prior radiation to the bone for fibrous dysplasia.
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