8: Tumors of the Oral Soft Tissues and Cysts and Tumors of the Bone

CHAPTER 8 Tumors of the Oral Soft Tissues and Cysts and Tumors of the Bone

Too often, dental practitioners see their responsibility to the patient begin and end with the care and maintenance of the teeth and periodontium. Physicians do not give oral health the attention it deserves because they, for the most part, do not receive education and training from this perspective. This leaves the responsibility to the dental practitioner to monitor and help maintain the overall health and well-being of the patient as evidenced in the orofacial and head and neck structures that are so obviously within their purview. Even so, it remains easy to focus strictly on the dental needs of the patient and remain oblivious to, among other things, subtle or even not so subtle lumps, bumps, swellings, or changes in texture or color that may signify the presence of a reactive or a hamartomatous overgrowth of tissue, or a benign or malignant disease. These disorders occur within the oral and maxillofacial region too often for the dentist to take the attitude that they happen only in someone else’s patients.

This chapter provides an overview of some of the more frequently encountered cysts and tumors in the oral and maxillofacial region soft tissues and bone in the pediatric age group.

BENIGN TUMORS OF THE ORAL SOFT TISSUE

SQUAMOUS PAPILLOMA AND VERRUCA VULGARIS

The squamous papilloma is a relatively common, benign neoplasm that arises from the surface epithelium. It is typically an exophytic lesion whose surface may vary from cauliflower-like to finger-like in appearance, and although it is generally a pedunculated lesion, it may arise from a sessile base. Although the average age of occurrence is in the fourth decade of life, nearly 20% of cases have been noted to occur before 20 years of age.1,2 The most common sites of occurrence appear to be the tongue and palatal complex, followed by the buccal mucosa, gingiva, and lips. This lesion is also seen with some frequency on the mandibular alveolar ridge, floor of the mouth, and retromolar pad regions.2

Oral verruca vulgaris, or oral warts, are exophytic papillomatous lesions indistinguishable clinically from oral squamous cell papillomas. Like their skin counterpart, the common wart (verruca vulgaris), they are a viral disorder associated with the human papillomavirus (HPV) and may be spread to the oral cavity in children through autoinoculation by finger or thumb sucking (Fig. 8-1). According to two reviews of HPV-associated diseases of oral mucosa, types 2 and 57 were most commonly found.3,4 DNA types 6, 11, and 16 have also been demonstrated in oral verrucae.5,6

Although the histopathologic differences between squamous papilloma and verruca vulgaris are subtle, these lesions are distinguishable from one another. Histologically, the papilloma is seen as a proliferation of the spinous cell layer in a papillary pattern, often with hyperkeratosis, acanthosis, and basilar hyperplasia. Mitotic figures may be prominent. The supporting fibrous connective tissue stroma often contains prominent numbers of small blood vessels as well as an inflammatory cell infiltrate. HPV may, however, be seen in squamous cell papillomas. In 1982 the presence of HPV genus-specific antigens was demonstrated in two of five multiple papillomas.7 In a subsequent review of the world literature analyzing 223 papillomas, the overall detection rate for HPV DNA was 49.8% with the most prevalent HPV types being HPV 6 and 11.4 HPV types 16 and 18 have also been detected in some squamous cell papillomas.8

The presence of papillomatosis often with convergence of rete ridges centrally, hyperkeratosis (either hyperparakeratosis or hyperorthokeratosis, or both) a coarse keratohyalin granular cell layer and vacuolated cells with pyknotic nuclei (koilocytes) may be used to differentiate verruca vulgaris from a squamous papilloma. Hence, from the above discussion both squamous papilloma and verrucous vulgaris should probably be considered benign, virus-induced epithelial hyperplasias and the identification of HPV does not appear to offer any diagnostic advantage because the histopathologic features alone allow for differentiation of one from the other.9

Treatment of either the oral squamous papilloma or verruca vulgaris is best accomplished by complete surgical excision of the lesion, including the base.

PYOGENIC GRANULOMA, PERIPHERAL OSSIFYING FIBROMA, PERIPHERAL ODONTOGENIC FIBROMA (WHO TYPE), AND PERIPHERAL GIANT CELL GRANULOMA

Pyogenic Granuloma

The pyogenic granuloma is a relatively common softtissue tumor that arises from the fibrous connective tissue of the skin or mucous membranes. Originally believed to be a botryomycotic infection, it is now known to be a reactive inflammatory process in which an exuberant fibrovascular proliferation of the connective tissue occurs secondary to some low-grade, chronic irritation.

Clinically the pyogenic granuloma is a raised lesion on either a sessile or a pedunculated base. Its surface may have a smooth, lobulated, or, occasionally, warty appearance that is erythematous and often ulcerated (Fig. 8-2). Depending on the age of the lesion, the texture varies from soft to firm and is suggestive of an ulcerated fibroma. Because of the pronounced vascularity of these lesions, they often bleed easily when probed. A review of pyogenic granulomas of the oral cavity revealed a 65% to 70% incidence of occurrence on the gingiva, most commonly the maxillary anterior labial gingiva, followed by the lips, tongue, buccal mucosa, palate, mucolabial or mucobuccal fold, and alveolar mucosa of edentulous areas.10 Twenty-seven percent of cases in this series of 46 patients were in individuals younger than 20 years of age. Another review of 38 cases reported an age range of 5 to 75 years (mean age, 33 years) with the most frequent site of occurrence also being on the gingiva (74%).10,11

Histologically the pyogenic granuloma presents as a remarkable proliferation of plump fibroblasts and endothelial cells with the formation of prominent numbers of thin-walled, endothelium-lined vascular channels. A polymorphous inflammatory cell infiltrate is present, and the overlying surface epithelium is often ulcerated. Treatment consists of surgical excision, with care being taken to completely remove any local irritant that may still be present that would predispose to recurrence of the lesion.

In addition to an ulcerated fibroma, which in fact may itself be a nearly healed or sclerosed pyogenic granuloma, both the peripheral ossifying fibroma and peripheral giant cell granuloma must be considered in the differential diagnosis of pyogenic granuloma because these lesions are clinically indistinguishable.

PERIPHERAL OSSIFYING FIBROMA AND PERIPHERAL ODONTOGENIC FIBROMA (WHO TYPE)

NEUROFIBROMA AND NEUROFIBROMATOSIS (VON RECKLINGHAUSEN’S DISEASE)

Neurofibroma is a benign neural neoplasm of Schwann cell origin of which several clinical forms are recognized. The solitary neurofibroma may present in the skin or oral mucous membranes as a soft tumor with a sessile or pedunculated base. Some neurofibromas are diffuse, presenting as a soft, nonspecific tissue mass or swelling. Although patients with neurofibromatosis may have either solitary or diffuse neurofibromas, the presence of either lesion does not in itself herald the diagnosis of this syndrome. The presence of a third form, the plexiform neurofibroma, is, however, considered to be diagnostic of neurofibromatosis. The plexiform neurofibroma differs from either the solitary or diffuse form in that it remains confined to the perineurium, presenting as a tortuous, fusiform enlargement of a nerve.

Neurofibromatosis type 1 (NF1), known as von Recklinghausen disease, is a relatively common disorder showing autosomal dominant inheritance with complete penetrance, variable clinical expressivity and pleiotropy, and age-dependent expression of clinical manifestations. It occurs in approximately 1 in 3000 live births with an equal sex predilection. The NF1 gene is carried on chromosome 17 and has tumor suppressor function, with the tumor-suppressing properties of neurofibromin (the NF1 gene product) then being impaired or lost. It is said to be the most common single-gene disorder to affect the human nervous system. The criterion for diagnosis is the presence of two or more of the following features: six or more café-au-lait spots (1.5 cm or larger in postpubertal individuals, 0.5 cm or larger in prepubertal individuals), two or more neurofibromas of any type or one or more plexiform neurofibromas, freckling in the axillary or inguinal region, optic glioma, two or more pigmented iris hamartomas or Lisch nodules, dysplasia of the sphenoid bone or dysplasia or thinning of long bone cortex with or without pseudoarthrosis, and a first-degree relative with NF1.

As previously noted, the NF1 gene is a tumorsuppressor gene, and thus patients with neurofibromatosis are at increased risk of developing benign and malignant tumors. Neurofibromatosis is a progressive condition with different presentations occurring at specific times with some complications worsening over time. While cutaneous or dermal neurofibromas are considered one of the characteristic features of this disorder and may appear in childhood, they more commonly develop in teenagers or adults. Although malignant peripheral nerve sheath tumors may be noted in pediatric patients with NF1, they usually develop in adulthood and are heralded by the presence of pain or rapid growth arising in a plexiform or deep nodular neurofibroma.20

Intraorally, neurofibromas may present as nodular lesions on either a sessile or pedunculated base, often with a normal, pink mucosal color (Fig. 8-3); as a diffuse, ill-defined swelling with a firm to doughy consistency; or as a diffuse, noncompressible mass. They are most frequently found on the tongue and buccal mucosa but occasionally present as intraosseous lesions, which occur most commonly in the posterior mandible (Fig. 8-4).

The most common radiographic findings include an increase in bone density, enlarged mandibular foramen, lateral bowing of the mandibular ramus, increase in dimensions of the coronoid notch, and decrease in the mandibular angle.21 Computed tomographic scans may reveal findings such as enlargement of the mandibular foramen and concavity of the medial surface of the ramus.

A great deal of histomorphologic variability may be noted, from relatively circumscribed but nonencapsulated solitary neurofibromas to diffuse and plexiform neurofibromas. The diffuse neurofibroma is characterized by its infiltrative growth pattern along connective planes and its Wagner and Meissner tactile corpuscles. Plexiform neurofibromas are characterized by fascicles of neoplastic Schwann cells and collagen within a myxoid matrix that is confined to the perineurium. Mast cells are common findings within neurofibromas.

Solitary lesions are best treated by simple surgical excision and show little propensity for recurrence. Surgical excision of diffuse neurofibromas is difficult because of their diffuse, infiltrating nature. Plexiform neurofibromas are also difficult to treat in that they have a tendency to grow along the course of a nerve, which results in frequent recurrences. It has been noted that (1) children younger than 10 years of age, (2) children with plexiform neurofibromas in the head, face, and neck, and (3) those with tumors that cannot be almost completely removed are at particular risk for progression of their lesions.22

HEMANGIOMA

Vascular anomalies are commonly encountered lesions of childhood and may be divided into hemangiomas and vascular malformations.23 Hemangiomas are differentiated from vascular malformations as they demonstrate proliferative activity while vascular malformations grow commensurately with the child.24 The hemangioma is a common, benign, vasoformative tumor that frequently occurs in the head and neck in children. It is generally believed to be hamartomatous rather than neoplastic in nature. Most hemangiomas are either present at birth or develop within the first year of life. It is believed that even those lesions that do not appear until adult life may have been present but not clinically evident until they began to enlarge.

Hemangiomas arising in the oral soft tissues most commonly affect the tongue, lips, and buccal mucosa. Clinically, they may be flat or raised and may vary from deep red to blue in color. Their histologic classification is based on the size of the vascular spaces. A capillary hemangioma is the most common type and is composed of many tiny capillaries with a pronounced endothelial cell proliferation. The cellular or juvenile hemangioma consists principally of a proliferation of endothelial cells with only small numbers of discernible capillaries. A cavernous hemangioma is characterized by large, blood-filled sinusoidal spaces lined by endothelial cells and supported by a fibrous stroma. Hemangiomas may also occur centrally within either the mandible or maxilla.

Vascular malformations most frequently involve the skin but also may affect visceral organs or bone. They may be categorized as fast-flow lesions and slow-flow lesions.25 Fast flow lesions include arterial malformations, arteriovenous malformations, and arteriovenous fistulas. Slow-flow lesions include capillary malformations, lymphatic malformations, and venous malformations. Vascular malformations of the mandible (i.e., arteriovenous malformations or central hemangioma of the mandible as they were sometimes called) are potentially dangerous in that a biopsy or simple event such as a tooth extraction may lead to a catastrophic hemorrhage possibly leading to death.26 These lesions may be asymptomatic, picked up only as incidental radiographic findings, or they may cause pain and swelling. They are typically well-circumscribed radiolucent lesions with no characteristic radiographic pattern to denote their underlying nature. Occasionally, loose or displaced teeth may be seen. Arteriovenous malformations bear a radiographic similarity to any number of other relatively wellcircumscribed unilocular or multilocular radiolucent lesions in the jaws. Therefore it is advisable to aspirate such lesions with a needle before surgery or dental extraction to avoid the possibility of severe blood loss or exsanguination caused by the inability to control the resultant profuse bleeding.

The treatment for hemangiomas varies with the type, location, and size of the lesion involved. Many lesions spontaneously involute with age, especially those that are noted early and cease growing during the first year of life. Others require no treatment because of their small size and innocuous nature.

LYMPHANGIOMA

Lymphangiomas are relatively rare benign congenital tumors of the lymphatic system. Even though the embryologic events leading to their development remain unclear, they are thought to arise as a benign hamartomatous proliferation of sequestered lymphatic rests. Forming along tissue planes or penetrating adjacent tissue, they become canalized and, in the congenital absence of venous drainage, accumulate fluid. The head and neck region is most commonly involved with up to two thirds of cases being present at birth and as many as 90% being present by the second year of life; a small number may not be manifest for a number of years.27

Lymphangiomas are classified on a histologic basis into three types: capillary lymphangiomas, cavernous lymphangiomas, and cystic hygroma. The capillary lymphangioma is typically composed of a proliferation of thin-walled, endothelium-lined channels primarily devoid of erythrocytes. The cavernous lymphangioma is characterized by the presence of dilated sinusoidal endothelium-lined vascular channels devoid of erythrocytes. The cystic hygroma is a macroscopic form of the cavernous lymphangioma, with large sinusoidal spaces lined with a single layer of endothelial cells that form multilocular cystic masses of varying sizes. Lymphangiomas of the oral soft tissues occur most commonly on the tongue, lips, and buccal mucosa. They are often elevated and nodular in appearance and may have the same color as the surrounding mucosa. Treatment is generally not indicated for small oral mucosal lymphangiomas; partial or complete spontaneous involution is occasionally noted.

Although cystic hygromas may be found in sites in the oral cavity, such as the tongue, they most frequently appear as a mass in the neck, occasionally extending into the mediastinum. Most commonly presenting as an asymptomatic soft tissue mass, they are usually slow growing; however, they may undergo sudden enlargement in the presence of trauma, inflammation, internal hemorrhage, or respiratory tract infection. Large cystic hygromas may encroach on the airway and esophagus, leading to difficulty in swallowing and even causing airway obstruction.

CONGENITAL EPULIS (GINGIVAL GRANULAR CELL LESION) OF THE NEWBORN

The congenital epulis of the newborn is a rare lesion of uncertain histogenesis that occurs exclusively in newborn infants, chiefly on the maxillary anterior alveolar ridge and less commonly on the mandibular anterior alveolar ridge. Although usually solitary lesions, they may be multiple, most often affecting both the maxilla and mandible although rare simultaneous occurrence of lesions on the maxillary anterior alveolar ridge and tongue have been reported. Clinically the lesion presents at birth as a pink, smooth to lobulated, pedunculated mass that may vary in size from a few millimeters to more than 7 cm in diameter. More than 90% of cases occur in girls (Fig. 8-5).

image

Figure 8-5 Congenital epulis of the newborn.

(Courtesy Dr. Robin Cotton.)

While typically considered a lesion of uncertain histogenesis, immunohistochemical studies have revealed strong and diffuse cytoplasmic staining for neuronspecific enolase and vimentin, which suggests that the congenital epulis may be derived from uncommitted nerve-related mesenchymal cells.28

Although histologic similarities to the granular cell tumor have long been noted, the epithelium over the congenital epulis is generally thin without rete ridge formation, whereas the granular cell tumor is characterized by pseudoepitheliomatous hyperplasia of the overlying epithelium; distinct differences are obvious on both ultrastructural and immunohistochemical evaluation. One differentiating factor between the congenital epulis and granular cell tumor tumors is the absence of S100 in the former and its presence in the latter lesion.29

Although the clinical presence of the congenital epulis may frighten parents, it ceases to grow following birth and is entirely benign, with some cases undergoing spontaneous involution. The usual treatment is simple surgical excision, with care taken not to interfere with the developing dentition. There is no propensity for recurrence, even in those cases in which the lesion is incompletely removed.

MUCOCELE

The mucocele, or mucus retention phenomenon, as it is often called, is a salivary gland lesion of traumatic origin that forms when the main duct of a minor salivary gland is torn with subsequent extravasation of mucus into the fibrous connective tissue so that a cystlike cavity is produced. The wall of this cavity is formed by compressed bundles of collagen fibrils, and its lumen contains inspissated mucin.

Mucoceles are noted to occur most commonly on the lower lip, with the floor of the mouth and buccal mucosa being the next most frequent sites of involvement. Mucoceles are only rarely seen on the upper lip, retromolar pad, or palate. Although they may occur at any age and have been reported to be present at birth, they tend to be noted most frequently in the second and third decades of life. No obvious sex predilection is noted.

A mucocele may be located either in the superficial mucosa, where it is typically seen as a fluid-filled vesicle or blister (Fig. 8-6), or deep within the connective tissue as a fluctuant nodule with the overlying mucosa normal in color. There may be spontaneous drainage of the inspissated mucin with temporary resolution, especially in superficial lesions, and subsequent recurrence as the mucous saliva continues to drain into the connective tissue at the site of the torn duct. Fibrosis may be observed over the surface of long-standing lesions where chronic periodic drainage has taken place.

Treatment is by surgical excision, with removal of the involved accessory salivary gland. Marsupialization will only result in recurrence.

BENIGN TUMORS OF BONE

FIBROUS DYSPLASIA

Fibrous dysplasia of the jaws is a distinct clinicopathologic entity that is generally considered to be a nonneoplastic developmental lesion of bone. One of a variety of disease entities included in the spectrum of benign fibro-osseous lesions of the jaws, it is distinguished from the others by its clinical and radiographic features. In the child and adolescent, it has most often been confused with the ossifying and cementifying fibroma, which is a benign neoplasm believed to be of periodontal ligament origin. Fibrous dysplasia is caused by a somatic activating mutation of the alpha subunit of the G protein (Gs-alpha) that ultimately results in abnormalities of osteoblast differentiation and therefore abnormal bone.

The two forms of fibrous dysplasia are (1) the relatively rare polyostotic form of the disease and (2) the considerably more common monostotic fibrous dysplasia. A severe form of polyostotic fibrous dysplasia called McCune-Albright syndrome is associated with café-au-lait macules on the skin and a variety of endocrine disorders, most commonly precocious puberty, but also including Cushing’s syndrome, hyperthyroidism, hyperparathyroidism, and diabetes mellitus.

Monostotic fibrous dysplasia tends to develop early in life with lesions being detected late in the first and early second decades.30 It is seen with approximately equal frequency in males and females, with the maxilla being involved more frequently than the mandible. Maxillary involvement can be an especially serious form of the disease, frequently involving contiguous bones across suture lines, including the maxillary sinus, floor of the orbit, sphenoid bone, base of the skull, and occiput. This form of the disease has been called craniofacial fibrous dysplasia and is not truly monostotic in its nature.

The most common clinical manifestation is a painless swelling of the jaws characterized by a smooth, uniform, fusiform expansion of the involved alveolar ridge. Obliteration of the mucobuccal or mucolabial fold is a common feature, with the overlying mucosa being normal in appearance. When the maxilla is involved, elevation of the eye may be noted.

Radiographically, maxillary lesions most often show a ground-glass appearance of the bone, whereas mandibular lesions usually show either a ground-glass or a mixed radiolucent-radiopaque appearance (Fig. 8-8). Their borders are typically poorly defined, except for the anterior portion of some maxillary lesions, which may appear to be well circumscribed. Divergence of roots may be noted, and in children in whom developing permanent teeth are present there may be displacement of teeth with noneruption (see Fig. 8-8). Other potential distinguishing radiographic findings include superior displacement of the mandibular canal and a fingerprint bone pattern as well as displacement of the maxillary sinus cortex, alteration of the lamina dura because of the abnormal bone pattern, and narrowing of the periodontal ligament space.31

Histologically there is a benign fibrous stroma with bony trabeculae varying from woven to lamellar in appearance, proportionate to the relative maturity of the lesion.

Monostotic fibrous dysplasia of the jaws is typically a slow-growing, painless, progressive enlargement of bone whose growth pattern often stabilizes with time as maturation in skeletal growth is reached. Conservative therapy is indicated because of the benign nature of this lesion and because surgically the margins are ill defined and blend into the surrounding normal bone. Surgery, chiefly in the form of osseous recontouring, should be considered only when there is functional or significant cosmetic deformity and then usually only after stabilization of the disease process. Because this is a benign lesion of bone, radiation therapy is contraindicated because of the possibility of development of a postradiation sarcoma in the area. In symptomatic cases in which pain control and disease stabilization are needed, bisphosphonates have been used, resulting in pain relief and, in a number of patients, disease stabilization as well.32 Little, however, is known about the long-term skeletal effects of childhood bisphosphonate use and it has been recommended that its use be limited to experienced pediatric units.32

OSSIFYING AND CEMENTIFYING FIBROMA

The ossifying fibroma is a benign neoplasm of bone grouped with fibrous dysplasia and other benign nonodontogenic tumors under the broad category of benign fibro-osseous lesions of the jaws. As with other benign fibro-osseous lesions, it is characterized histologically by a benign fibrous stroma, with formation of variable amounts of woven-appearing bone, lamellar bone, and spherical to annular to amorphous cementum-like calcifications. Although it was traditionally considered to be an odontogenic neoplasm of periodontal ligament origin affecting the tooth-bearing areas of the jaws, the occurrence of histologically identical neoplasms in the temporal, frontal, ethmoid, and sphenoid bones leaves this concept in doubt. When the cementum or cementum-like calcifications predominate, the term is cementifying fibroma. When both bone and cementum-like tissues are present, the lesions are termed cemento-ossifying fibromas. Although there is a predilection for occurrence in the third and fourth decades of life, the ossifying fibroma is found with some frequency in patients younger than 20 years of age. The mandible is involved more often than the maxilla, with the molar and premolar region of the mandible being the most common site of occurrence.

The ossifying fibroma may be entirely asymptomatic, being discovered on routine radiographic examination, or may present as a painless expansion of bone. Radiographically the ossifying fibroma is a well-circumscribed lesion, often with a well-demarcated sclerotic border (Fig. 8-9). Beyond this, the radiographic features are quite variable.33 It most frequently presents as a unilocular radiolucency with or without radiopaque foci, which may be superimposed over teeth, may be interposed between contiguous teeth, or may reside in edentulous regions. Aggressively expansile lesions with or without radiopaque foci as well as multilocular expansile lesions may also be noted. Tooth displacement or divergence of roots of teeth and/or root resorption may be seen with varying degrees of frequency with tooth displacement or root divergence being reported in from 17% to 33% of cases and root resorption being seen between 11% and 44% of the time.33,34 Cortical thinning and bony expansion with clinical deformity have been reported in as many as 91% of cases.

Initial treatment is by enucleation or curettage where possible, with the frequency of recurrence varying from 0% to 28%.33,35

JUVENILE OSSIFYING FIBROMA

The term juvenile ossifying fibroma (JOF), also known as juvenile active ossifying fibroma and juvenile aggressive ossifying fibroma, encompasses two distinct clinicopathologic variants of ossifying fibroma involving the craniofacial bones: the trabecular juvenile ossifying fibroma (TrJOF) and the psammomatoid juvenile ossifying fibroma (PsJOF). The TrJOF affects both the maxilla and the mandible with the maxilla being involved slightly more frequently.36 Occurrence in extragnathic locations is extremely rare.30 The reported mean age ranges from 8{½} to 12 years (range, 2 to 12 years). The PsJOF was noted to occur predominantly in the sinonasal and orbital bones in patients with a mean age range of 16 to 33 years (range, 3 months to 72 years). Aggressive growth was noted to occur in some cases of both types with a high recurrence rate after excision (30% to 56% of cases). It has been proposed that despite some similarities in biologic behavior, differences in histologic, demographic, and clinical presentation between PsJOF and TrJOF warrants their se/>

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Jan 14, 2015 | Posted by in Pedodontics | Comments Off on 8: Tumors of the Oral Soft Tissues and Cysts and Tumors of the Bone
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