Cysts of the Oral Cavity PDF

# Cysts of the oral cavity ## II. Non-odontogenic cysts ### Nasopalatine canal (duct) cyst - It is a developmental cyst arising from epithelial remnants of the nasopalatine duct which located in the midline of anterior maxilla between and posterior to the central incisor teeth. - Cyst of the pala...

# Cysts of the oral cavity ## II. Non-odontogenic cysts ### Nasopalatine canal (duct) cyst - It is a developmental cyst arising from epithelial remnants of the nasopalatine duct which located in the midline of anterior maxilla between and posterior to the central incisor teeth. - Cyst of the palatine papillae is the soft tissue variant of nasopalatine duct cyst. ### Clinical features - It occurs in fifth or sixth decades. - Males are more affected than females. - Asymptomatic unless infected, slowly growing and discovered on routine examination. ### Radiographic features - Well-defined round, ovoid or heart shaped radiolucency with sclerotic rim that is located at the mid line or displaced to one side. - The anterior nasal spine is usually centrally superimposed on the radiolucent defect, resulting in a heart shape. ### Histological features - The lining is stratified squamous epithelium (when cyst arises toward the oral end of the canal), pseudostratified ciliated columnar epithelium (when cyst arises toward the nasal cavity), or combination of both types of epithelium. - The connective tissue wall contains neurovascular bundle (formed of small arterioles from greater and lesser palatine arteries. In addition to nerve tissues from sphenopalatine nerve). ### Differential diagnosis - Periapical granuloma. - Periapical cyst. ### Treatment - Enucleation if the size of the cyst is small. - Marsupialization if the cyst is of large size. ## Nasolabial cyst It is a rare lesion which arises in the soft tissue of upper lip just below the ala of the nose. ### Pathogenesis - It is suggested to be fissural cyst, arising from the remnants of the epithelium at site of fusion between medial and lateral nasal processes of the maxilla. ### Clinical features - It occurs mostly in the fourth decade. - Females are more affected. - It may be bilateral. - It grows slowly obliterating the nasolabial fold and distorting the nostrils. ### Histological features - The cysts are usually lined by pseudostratified columnar epithelium. However, stratified squamous epithelium and mucous cells may be present. ### Differential diagnosis - Radicular inflammatory cyst. ## Globulomaxillary cyst - It is a very rare cyst occurring between the roots of the maxillary permanent lateral incisor and the canine. ### Pathogenesis - It was thought to develop from epithelial remnants following the joining of the globular portion of medial nasal process with the maxillary process. ### Radiographic features - It presents as an inverted unilocular pear-shaped radiolucency. ### Histologic features - Usually lined by pseudo stratified columnar epithelium. ## Median cysts ### Median palatine cyst - It is very rare. - It was thought to be from epithelium entrapped along line of fusion of lateral palatal shelves of maxilla. - It is more accepted to represent posteriorly positioned nasopalatine duct cyst. ### Median mandibular cyst - It was thought to be fissural due to epithelial rests entrapped during the fusion of the halves of the mandible during embryonic life. ## III. Non epithelialized primary bone cysts (pseudo cysts) ### Solitary bone cyst Also may be termed (Simple bone cyst, traumatic bone cyst and hemorrhagic bone cyst) ### Pathogenesis - It is unknown. However, it is believed that it is related to either: - Trauma to the mandible leads to central hemorrhage inside the bone. Failure of organization of blood clot with degeneration of blood clot resulting in an empty cavity (hemorrhagic bone cyst). - Or may be related to hemodynamic disturbance in medullary bone. ### Clinical features - Usually seen in children and adolescents, mainly in the second decade. - Site: mandible is more affected than maxilla, in the area between canine and ascending ramus. - It is asymptomatic and usually found accidently in x-rays. - Only 25% of cases may show expansion of bone. ### Radiographic features - It is of highly suggestive radiographic picture that aids in the diagnosis. - It shows well-defined unilocular radiolucency of variable size and irregular outline. - It has scalloping or festooning outline around and between the roots of teeth. ### Histological features - Surgical exploration confirms diagnosis, as it reveals a rough empty bony-walled cavity with no soft tissue lining. - In other cases little clear or blood-stained fluid is seen in the cystic cavity. ### Histologic examination of curetted masses shows: - Delicate layer of loose, vascular connective tissue. - Hemosiderin pigments. - No epithelial lining. ### Treatment It resolves after surgical opening and closure, or occasionally spontaneously. ## Aneurysmal bone cyst - It is a blood filled, pseudocyst occurring within the bone either as a primary lesion or a secondary complication to other bone lesions. ### Pathogenesis - It is of unknown cause but it may arise due to either: - Trauma. - Or, preceded by some other primary lesions of bone such as fibrous dysplasia, giant-cell granuloma or vascular malformation. ### Clinical features - Age: under 30 years of age. - Site: commonly posterior part of the mandible. - Pain is often reported although many cases are painless. - It shows rapidly developing swelling. - On palpation, it is non-pulsatile. ### Radiographic features - It presents as a unilocular or more commonly multilocular radiolucency with ballooned-out appearance due to gross cortical expansion. ### Histological features - It has no epithelial lining. - Sinusoidal blood spaces not lined by endothelial cells but lined by fibroblasts and macrophages (histiocytes). - The fibrous septa in-between contains multinucleated giant cells, extravasation of RBC's and new bone formation. ### Differential diagnosis - As it forms very expansile soap-bubble radiolucencies, it may be mistaken clinically and radiographically for ameloblastoma or odontogenic keratocysts ### Treatment - The treatment of Aneurysmal bone cyst is surgical, either conservative or radical. - Curettage is frequently recommended, but is a source of recurrence in 20 to 53% of cases. ## Stafne's idiopathic bone cavity (Static bone defect, Latent bone cyst) - It is uncommon developmental anomaly of the mandible. It is a saucer-shaped depression on the lingual aspect of the mandible. It contains ectopic salivary tissue in continuity with the submandibular salivary gland. ### Clinical features - It is symptomless and discovered accidentally on routine x-ray examination. ### Radiographic features - It appears as a round or oval well demarcated radiolucency between the premolar region and angle of the mandible. - Usually beneath the inferior dental canal. - Usually bilateral. ### Diagnosis: - By Sialography. ### Treatment: - No treatment. ## IV. Soft tissue cysts ### 1. Benign cervical lymphoepithelial cyst (old name: branchial cyst). Arises at the lateral aspects of the neck. ### Pathogenesis - It was thought to arise from cystic degeneration of the epithelial remnants, found between the branchial arches. - Recently, it has been proposed that it arises due to entrapment of epithelium within cervical lymph nodes, followed by cystic degeneration. ### Clinical features - It is seen in late childhood or adulthood. - Found at the lateral aspect of the neck, anterior to the sternomastoid muscle. - May be infected, with abscess formation and draining sinus. ### Histological features - Usually lined by stratified squamous epithelium or pseudostratified columnar epithelium. - The underlying connective tissue shows lymphoid aggregates usually demonstrating well-formed germinal centers. ### Treatment - It is treated by surgical excision. ### Dermoid cyst - It is a mid-line cyst which develops between the hyoid bone and the mandible. ### Pathogenesis - It originates from entrapment of epithelium in the mid line due to incomplete fusion of the mandibular and hyoid branchial arches. ### Clinical features - It develops at birth. - It arises in the midline, where it has 2 locations: - Typical cysts located above the geniohyoid muscle between it and the oral mucosa. It leads to bulge in floor of the mouth and elevate the tongue resulting in difficulties in mastication and speech. - Some cysts located deeply between geniohyoid muscle and mylohyoid muscle. It leads to submental swelling (double chin). - Its size ranges from 2 to 8 cm. Some reach huge size till 12 cm. - It appears as soft fluctuant swelling that is pale yellow in color. - When keratin debris and sebum (secretion of sebaceous glands) fill the cystic lumen, it becomes doughy in consistency. - If infection occurs it leads to development of a sinus tract which opens intraorally. ### Histological features - It is lined by orthokeratinized stratified squamous epithelium. - The supported fibrous connective tissue wall reveals skin appendages, as sebaceous gland, sweat glands and hair follicles. ### Cyst content - The lumen contains keratinous debris. - Sebum is also seen in the cyst cavity, when sebaceous glands are seen. - The cyst that contains keratin only in the cystic cavity without skin appendages in the fibrous wall is termed epidermoid cyst. ### Treatment - The cyst is surgically removed. ### Epidermoid cyst - keratin-filled cyst often arise after localized inflammation of the hair follicle ### Thyroglossal duct cyst - The most common developmental cyst in the neck. - It is one of midline cysts. ### Pathogenesis - It arises from the residues of the embryonic thyroglassal duct that extends from foramen caecum in the tongue to the location of the thyroid gland. ### Clinical features - It has two different locations: - In the midline of the neck in the region of hyoid bone (most common). It presents as a movable swelling. The cyst moves with the movement of the tongue and upon swallowing. - In tongue substance (lingual thyroid), if the cyst arises in a position high in the duct. - If infection occurs, drainage through sinus occurs. ### Histological features - Microscopic findings vary depending upon the location of the cyst: - Above level of hyoid bone, it is lined by stratified squamous epithelium. - Below level of hyoid bone, it is lined by ciliated or columnar epithelium. - Thyroid tissue may be seen within the connective tissue wall. ### Treatment - It is treated by complete surgical excision. - Before excision of ectopic lingual thyroid it is important to make sure that the patient has functioning thyroid tissue in the neck. ### Salivary gland cysts (Mucocele) ### 1- Mucous extravasation cyst - It is the most common type of mucoceles in the minor salivary glands. It is not a true cyst as it has no epithelial lining. ### Pathogenesis - Mechanical trauma to the minor salivary gland excretory duct resulting in its transaction. - Spillage or extravasation of mucous in the surrounding connective tissue, inducing secondary inflammatory reaction. - Granulation tissue response, resulting in the formation of a wall around the mucin pool. ### Clinical features - Usually affects the lower lip, buccal mucosa and floor of the mouth. It may be seen in the ventral surface of the tongue. - It occurs at any age, but usually in the second decade. - It is usually superficial and rarely larger than 1 cm in diameter. - It appears as a bluish submucosal swelling. - There may be history of rupture, collapse and refilling. ### Histological features - Well circumscribed cavity containing mucin surrounded by a thin wall of compressed granulation tissue. - The wall is infiltrated by large number of neutrophils, macrophages, lymphocytes and plasma cells. ### Differential diagnosis - Salivary neoplasms. - Vascular malformations. - Lipoma. - Gingival and eruption cysts (if mucocele appears in alveolar mucosa). ### Treatment - It should be excised with underlying gland to prevent recurrence. ### 2- Mucous retention cyst - It is a true cyst that is derived from cystic dilatation of a duct and so it is lined by ductal epithelium. ### Pathogenesis - The duct usually becomes obstructed, and so mucin does not escape. ### Clinical features - Less common than the extravasation type. - Appears over 50 years of age. - It is seen in the floor of the mouth, palate, cheek and may be seen in the maxillary sinus. - Asymptomatic swelling with size of 3 to 10 mm. - It is mobile, non-tender and shows no inflammation. ### Histological features - Cystic cavity surrounded by ductal epithelium, which is usually a double layer of columnar or cuboidal cells. - Mucin is found inside the cavity. - Surrounding connective tissue lacks inflammation. ### Differential diagnosis - Salivary neoplasms. - Extravasation mucocele. - Connective tissue neoplasms. ### Treatment - Complete removal of the mucous retention cyst and associated lobules of minor salivary glands. ### Ranula - Latin word; "rana” means frog - Uncommon type of salivary cyst arising from sublingual or submandibular salivary glands. - Source of mucin spillage is usually sublingual gland to a lesser extent from submandibular gland duct or possibly from minor salivary glands in floor of mouth. ### Clinical features - It is usually unilateral, or may extend across the whole floor of the mouth. - They are soft, bluish and fluctuant of 2-3 cm in diameter. - Painless but may interfere with mastication and speech. ### Histologic features of ranula: - The histologic appearance is similar to mucoceles from other locations. ### Differential diagnosis - Dermoid cyst, which is different in being "doughy" in consistency and more towards the midline. - Salivary gland tumors. - Benign mesenchymal tumors. ### Treatment - Surgical removal is the preferred therapy. - Excision of the involved gland is usually performed as well.