Developmental cyst arising from gastrointestinal epithelium.

Rather rare cyst.

May become manifest already during infancy or childhood. The most common location is the midline of the floor of the mouth (Fig. 2.3).

Histopathologic examination will show a cyst lined by stratified squamous epithelium (epidermoid cyst); in the presence of adnexal structures (e.g., sebaceous glands or hair follicles), one is dealing with a dermoid cyst (Fig. 2.4b, c).

Enucleation; recurrences are rare.

Developmental cyst characterized by presence of a gastrointestinal epithelial lining of the cyst wall.

Rare cyst with less than 100 cases published in the literature.

Usually already present at birth or shortly thereafter. Presents itself as a cystic swelling in the anterior part of the floor of the mouth (Fig. 2.5).

The cyst wall is lined by gastrointestinal epithelium (Fig. 2.6). Sometimes it is difficult to really demonstrate the gastrointestinal origin of the epithelial lining.

Enucleation; recurrences are rare.

Developmental cystic lesion, sometimes forming a crypt like in the tonsils, arising from epithelium that has been entrapped in lymphoid tissue; is also referred to as “oral tonsil.”

Rather rare cyst; may occur at all ages.

Yellowish, circumscribed swelling, asymptomatic otherwise (Fig. 2.7). Usually solitary or multiple presentation. The floor of the mouth and ventral aspect of the tongue are the most common locations. The differential diagnosis includes mainly ranula and lipoma.

The cyst is lined by stratified squamous epithelium and surrounded by lymphoid tissue (Fig. 2.8).

In general removal is recommended, mainly for histopathologic verification. Recurrences have not been reported.

Developmental cyst arising from epithelium enclosed in the lower part of the nasolacrimal duct.

Rare cyst; mainly diagnosed during adulthood.

Paramedian swelling in the upper mucobuccal fold and, extraorally, of the nasolabial fold (Fig. 2.9). Radiographically, some erosion of the underlying maxillary bone may be observed.

The cyst is lined by cylindrical epithelium (Fig. 2.10). Occasionally, the lining consists of squamous epithelium.

Enucleation through an intraoral approach; recurrences are rare.

Retention of mucous material in the excretory duct of minor salivary gland or the sublingual gland in case of involvement of the floor of the mouth; occasionally, extravasation in the surrounding connective tissue.

Most likely caused by traumatic obstruction of the orificium of the duct.

Rather common cyst; may occur at all ages.

Bluish, non-painful, recurrent cystic swelling. Occurs mainly in the lower lip (mucocele) and in the floor of the mouth (ranula) (Fig. 2.11a, b). Rarely occurs at the ventral aspect of the tip of the tongue (see also Chap. 4) or the palate.

A special variant of the ranula is the “plunging” ranula, in which the cyst herniates through the mylohyoid muscle, presenting itself as a submental or submandibular swelling. The differential diagnosis of a mucous cyst includes a cystic salivary gland neoplasm, (arterio)venous malformation, and phlebectasia, particularly when located on the lower lip.

Histopathologically, a lumen is seen filled with mucous and cell debris. The lumen may be lined by ductal epithelium (“retention type”); in case of absence of an epithelial lining, one is dealing with the “extravasation type.”

A mucocele of the lower lip can usually easily be removed in toto; recurrences are rare. In case of a mucocele at the ventral aspect of the tip of the tongue, the removal of the associated, surrounding minor salivary glands is indicated in order to prevent recurrences.

A ranula is usually primarily treated by marsupialization. In case of recurrence, the removal of the underlying sublingual gland may be required. In case of a “plunging ranula” intraoral removal of the associated sublingual gland usually suffices.

A fibroma of the oral mucosa represents a hyperplastic lesion rather than a neoplastic one; sometimes the term “fibroepithelial polyp” is used.

The rare “solitary fibrous tumor” of the oral mucosa will not be discussed here; this tumor does not have a characteristic clinical presentation, and the diagnosis is solely based on histologic criteria, resembling the somewhat questionable entity of hemangiopericytoma.

Chronic, mechanical irritation caused by habitual biting on the mucosa, by a broken-down dental restoration, or by an ill-fitting partial or full denture. The etiology of “symmetrical fibromas” of the palate or the lingual aspect of the mandible near the trigonum region is unknown.

Often pedunculated, usually solitary lesion, occurring particularly at sites of mechanical irritation such as the buccal mucosa, the tip of the tongue, and along the borders of a denture. In the latter event, the term “denture hyperplasia” or “epulis fissuratum” is used (Figs. 2.14 and 2.15a, b). The consistency of a fibroma may vary from soft to firm elastic. Fibromas are asymptomatic otherwise.

Symmetrical fibromas may occur on the hard palate and on the lingual aspect of the trigonum region of the mandible (Fig. 2.16).

The differential diagnosis includes lipoma, pyogenic granuloma, and other neoplasms either benign or malignant such as a non-Hodgkin lymphoma or a metastasis. A unilateral fibroma-like lesion on the palate may also be caused by a salivary gland neoplasm.

Multiple fibroma-like swellings may be part of the multiple hamartoma syndrome (Cowden syndrome; a rare hereditary syndrome in which the patient is prone to develop a variety of benign or malignant tumors; see also Chap. 4).

In tuberous sclerosis, a (sometimes hereditary) syndrome in which a variety of abnormalities may occur, oral involvement consists a.o. of fibrous hyperplasia of the oral mucosa and the gingiva (Figs. 2.17 and 2.18), enamel pitting, and radiolucencies in the jaws based on fibrous connective tissue that may cause eruption disturbancies.

In Crohn’s disease, fibroma-like swellings of the buccal mucosa may occur. These swellings may have a cobble stone appearance (Fig. 2.19a, b).

On histopathologic examination of a fibroma fibrous tissue is seen with or without the presence of an inflammatory infiltrate. Occasionally, stellate-like, large fibroblasts are observed, referred to as “giant cell fibroma”; this histopathologic subtype does not have any clinical relevance (Fig. 2.20a, b).

Elimination of the etiologic factor, if identified, is sometimes effective. If not, excision and histopathologic verification may be considered. Recurrences are rare.

Benign neoplasm of fat cells.

Fibroma-like appearance, sometimes showing a somewhat yellowish color, having a soft consistency (Fig. 2.21), being otherwise asymptomatic. Bilateral, symmetrical occurrence is extremely rare.

Histopathologically, mature, well-encapsulated fat cells are seen (Fig. 2.22). There are a few histologic subtypes such as fibrolipoma and angiolipoma; these subtypes are not of clinical significance. The malignant variant of a lipoma, referred to as liposarcoma, rarely occurs in the mouth.

Surgical removal. Lipomas rarely, if ever, recur.

Rare, somewhat questionable entity of unknown etiology, possibly representing the counterpart of cutaneous focal mucinosis; may be just a fibroma with myxoid changes of the connective tissue.

Pedunculated, fibroma-like swelling that may occur on the gingiva, palate, and buccal mucosa, being asymptomatic otherwise (Fig. 2.23).

Histopathologically, a somewhat circumscribed myxoid fibromatous lesion can be observed without the presence of an inflammatory infiltrate (Fig. 2.24).

Surgical removal.

Benign neoplasm derived from perineural fibroblasts and Schwann cells; can be part of hereditary neurofibromatosis type I.

Rather uncommon tumor of the oral soft tissues.

Solitary or multiple firm-elastic swelling of the oral mucosa, usually asymptomatic otherwise. The tongue and the buccal mucosa are the sites of predilection. Occasionally, the palate is involved (Fig. 2.25).

Histopathologically, the lesion is usually well circumscribed. Proliferation of spindle cells in a collagen-rich matrix can be observed (Fig. 2.26).

A solitary neurofibroma can be removed by surgical excision. In patients suffering from neurofibromatosis type I, malignant transformation may occur. Because of the often widespread occurrence throughout the body, prophylactic removal of these neurofibromas is not feasible. Instead, regular, lifelong follow-up is recommended.

Benign neoplasm derived from Schwann cells.

Rare intraoral neoplasm.

Circumscribed firm-elastic swelling, usually asymptomatic otherwise (Fig. 2.27).

Histopathologically characterized by two cell types, being “ Antoni-A cells” (with elongated nuclei and arranged in a palisade pattern around acellular collagen-like structures, so-called Verocay bodies) and Antoni-B cells (Fig. 2.28).

Surgical removal.

Proliferation of neural structures caused by trauma (“traumatic neuroma”). Multiple mucosal neuromas are indicative of the hereditary multiple endocrine neoplasia (MEN) type 2B syndrome, also referred to as Sipple syndrome (Fig. 2.29).

Circumscribed solitary or multiple swellings of the lower lip or the tongue, sometimes painful. In case of multiple neuromas, the lips, tongue buccal mucosa, gingiva, and palate may be involved.

The histopathology is characterized by a haphazard proliferation of nerve bundles. In MEN type 2B syndrome, distinct hyperplasia of nerve bundles can be seen.

A traumatic neuroma can be excised, together with a part of the associated nerve bundle.

In MEN type 2B, the emphasis is on early detection of the possible development of thyroid cancer.

Excessive tissue reaction to nonspecific local irritation. In the past believed to be caused by pus-producing microorganisms, hence the adjective “pyogenic.” Is by some regarded as a vascular lesion (“lobular capillary hemangioma”).

Soft, pedunculated, and usually partly ulcerative swelling, usually asymptomatic otherwise (Fig. 2.30). May occur at any site in the oral cavity, except for the floor of the mouth.

Vascular spaces surrounded by clusters of endothelial cells (“lobular capillary hemangioma”); there may be secondary signs of inflammation (Fig. 2.31).

Conservative surgical excision; recurrences are rare.

Generalized granulomatous disease.

Unknown.

Rather uncommon disease; may become manifest during adolescence.

In 90 % of patients suffering from sarcoidosis, the lungs are involved. Oral involvement is rare and consists of solitary or multiple nodules of the oral mucosa (Fig. 2.32).

Histopathologically, noncaseating granulomas are observed (“sarcoid granulomas”); these do not allow to make a firm diagnosis of sarcoidosis and require additional medical examination (Fig. 2.33).

Treatment is only indicated in active disease and usually consists of systemic administration of corticosteroids.

Inflammation of minor salivary glands. Subacute necrotizing sialadenitis (SANS) of the palate is a separate entity that will be discussed in Chap. 6.

Usually in adults and elderly patients.

Probably the result of an ascending infection from the oral flora through the excretory ducts of the minor salivary glands (“retrograde” infection).

Occurs mainly in the upper and lower lip (cheilitis glandularis; see also Chap. 3) and the buccal mucosa. Presents as recurrent, solitary, or multiple firm-elastic swellings of the mucosa (Fig. 2.34). Sometimes painful and occasionally resulting on abscess formation. On careful massage of the nodule(s), some mucopurulent discharge may be observed.

In case of a solitary swelling of the oral mucosa, the possibility of a salivary gland neoplasm should be considered as well as the rare event of a sialolith. The final diagnosis can only be established by histopathologic examination.

Nodular lesions of the lips and the cheek may also be the result of a foreign body reaction to fillers.

Histopathologic examination shows a nonspecific inflammatory reaction in the salivary gland tissue (Fig. 2.35).

In case of a solitary lesion, a biopsy is usually sufficient; in case of multiple lesions, the treatment policy is mainly guided by the presence of symptoms.

Tumor usually arising from the parenchymal epithelial salivary gland tissue and rarely from the stromal part of the salivary glands.

Unknown; in an occasional patient, there is a history of previous irradiation in the head and neck region that may have caused the tumor.

The incidence of salivary gland tumors, including the ones that occur in the major salivary glands, is approximately 3 per 100,000 population per year, for benign and malignant tumors together. May occur at all ages, although occurrence in children is rather rare.

Usually a slowly growing, firm-elastic fibroma-like swelling, sometimes of cystic consistency, of the oral mucosa, being asymptomatic otherwise. Sites of preference are the palate, particularly at the junction of the hard and soft palate (see also Chap. 6), the upper lip and, rarely, the buccal mucosa and the floor of the mouth (see also Chap. 3) (Fig. 2.36).

The percentage of occurrence in all salivary glands is as follows:

Based on the clinical signs and symptoms, no reliable distinction can be made between a benign or a malignant salivary gland tumor, and in all instances, a biopsy is required, preferably taken in the center of the swelling and deep enough to obtain representative tissue.

Histopathologically, there is a wide range of benign and malignant salivary gland tumors (Table 2.1). It may be difficult for the pathologist to provide a firm histopathologic subtype of a salivary gland tumor based on a biopsy.

The adenoid cystic carcinoma is a rare intraoral salivary gland tumor known for its perineural spread (Fig. 2.37) and rather poor prognosis.

Surgical removal; postoperative irradiation on indication. Malignant salivary gland tumors may metastasize to the cervical lymph nodes. The adenoid cystic carcinoma often produces distant metastases, skipping the regional lymph nodes in the neck.

A sialolith (calculus formation) in the duct of a minor or major salivary gland; occasionally in the gland itself, e.g., in the submandibular or the parotid gland.

Deposition of debris possibly caused by infection and followed by calcification. There is no association between calculus formation in the salivary glands and other organs, e.g., kidney and gall bladder.

Rather rare event; usually at middle age but may occur in children as well.

Sialoliths mainly occur in the submandibular glands or their excretory ducts and are usually associated with symptoms of a painful, recurrent submandibular swelling, particularly during meals. Occasionally presents as a swelling in the floor of the mouth (Fig. 2.38a). The diagnosis is confirmed by the findings on an occlusal radiograph (Fig. 2.38b) or a (cone beam) CT (Fig. 2.38c, d).

Occurrence of a sialolith in a minor salivary gland is quite rare; the usual presentation is a small nodule in the upper lip.

Treatment consists usually of surgical removal. In most cases of involvement of the submandibular ductal system, there is no need to also remove the associated submandibular gland. Some clinicians prefer to apply lithotripsy. Removal of a sialolith in the parotid gland is more cumbersome; sometimes sialoendoscopic removal is possible. An intraoral sialolith can be simply enucleated (Fig. 2.39).

Acute or chronic infection of the cervicofacial region caused by actinomycetes. Actinomycetes are actually no fungi but normal, saprophytic bacteria of the oral flora. There are several subclasses of actinomycetes such as A.israelii and A. viscosus.

Trauma, e.g., a tooth extraction, may be the “port d’entrée” of the infection, resulting in abscess formation that ultimately may cause a cutaneous fistula. In most cases, there is an interval of some months between the extraction and the clinical presentation of the disease.

Rather rare disease in the head and neck region.

Usually presenting as a firm infiltrate or abscess, showing a bluish-reddish discoloration of the overlying skin (Fig. 2.42).

Culturing of pus or infected tissue does not always demonstrate the presence of actinomycetes; in a number of such cases, histopathologic examination is helpful (Fig. 2.43).

Surgical drainage and debridement followed by a 6–12-week course of penicillin.

Fungal infection caused by one of the Candida species, most often being C. albicans.

Systemic predisposing factors consist of immunodeficiencies (e.g., HIV infection), diabetes mellitus, malnutrition, hematologic disorders such as leukemia, and prolonged use of antibiotics.

There are several clinical manifestations; these may occur simultaneously in an individual patient. There is almost always a bilateral, more or less symmetrical pattern.

The pseudomembranous type (“thrush”) is characterized by white plaques that can be easily wiped off from the mucosal surface (Fig. 2.44); this type mainly occurs on the buccal mucosa and the tongue. Symptoms may consist of a burning sensation and an abnormal taste.

The erythematous type is characterized by sometimes painful, fiery red changes of the mucosa, particularly occurring on the palate and the dorsum of the tongue (Fig. 2.45). Median rhomboid glossitis is regarded as a variant of erythematous candidiasis (see Chap. 4), being sometimes associated with erythematous candidiasis of the palate (“kissing lesion”); C. albicans may also play a role in angular cheilitis (“perlèches”); furthermore, denture stomatitis may be a variant of erythematous candidiasis, although the etiologic role of C. albicans in this condition is less convincing than has been thought in the past. In the absence of a bilateral distribution, the clinician should consider a diagnosis of erythroplakia, being a rare but serious premalignant disorder.

The mucocutaneous type is caused by an underlying immune disorder and affects the oral mucosa, the skin, and nails. This rare entity will not be discussed here any further.

In most instances, the diagnosis “candidiasis” is a clinical one, either based on the clinical presentation or on a positive response to antifungal treatment.

In the hyperplastic type, one may consider to perform a biopsy. In such event hyperplastic, parakeratotic epithelium can be observed with hyphae penetrating the epithelium (Fig. 2.46); in the superficial epithelium, microabscesses may be encountered. There may be varying degrees of chronic inflammation in the subepithelial connective tissue and sometimes also presence of neutrophils in the epithelium.

Treatment is mainly indicated in symptomatic cases and should primarily be directed at elimination of predisposing factors, if any. In many cases, topical antifungal treatment for a few weeks is sufficient; only in persistent cases, systemic antifungal treatment is indicated.

Angina hemorrhagica bullosa is the Latin term for a painful blood blister.

Unknown; some patients report that the lesion arose after eating hard food substances.

Rather rare event; mainly in adults and probably more often in women.

The blister suddenly appears and is often associated with pain. The palate, buccal mucosa, and the borders of the tongue are the sites of preference (Fig. 2.47). The blister ruptures soon after its development, leaving a superficial erosion of the mucosa behind (Fig. 2.48a, b).

Treatment is rarely required since the blister ruptures soon after its development. Further healing takes place without scar formation.

Some patients will experience repeated recurrences. Unfortunately, no preventive measures can be taken.

Local dilatation of a small vein.

Is most likely an aging phenomenon and is the result of local weakness of the vascular wall. Is not a sign of cardiopulmonal disease.

Common phenomenon in middle-aged and elderly people.

Solitary or multiple bluish swellings ranging from a few millimeters up to a centimeter (Fig. 2.49). The borders and the ventral aspect of the tongue and also the lips are the sites of preference. Phlebectasias are asymptomatic otherwise. There is rarely a need for histopathologic confirmation.

Vascular spaces filled with erythrocytes (Fig. 2.50a). Thrombus formation may occur, sometimes accompanied by intravascular papillary endothelial hyperplasia. In such instance, the term “Masson tumor” has been used in the past; this benign lesion can be misdiagnosed as an angiosarcoma (Fig. 2.50b).

Not required, although patients occasionally ask for removal because of esthetic reasons.

The majority of the so-called hemangiomas of the oral mucosa and soft tissues are present already at birth or shortly thereafter and represent a malformation of blood vessels or lymphatic vessels (lymphangioma) rather than a neoplasm. There is, however, a rare “true” hemangioma that arises shortly after birth, showing rapid proliferation followed by spontaneous involution during childhood (Fig. 2.51). The present text focusses on the arteriovenous malformations.

Red or bluish swelling of the oral mucosa, with or without pulsations, being usually asymptomatic otherwise. Only in arterial malformations repeated and severe spontaneous bleeding may occur. The lips, the tongue, and the buccal mucosa are the sites of preference (Fig. 2.52). Occasionally, calcified structures may be observed on a plain radiograph due to calcifications of thrombosed tissue; these are referred to as phleboliths (Fig. 2.53).

The differential diagnosis includes cystic salivary gland tumor, ecchymosis, petechiae due to thrombocytic disease (Fig. 2.54