Cysts & Tumors

💡INFLAMMATORY ODONTOGENIC CYSTS

💡Radicular cyst (periapical cyst)

The radicular cyst is the most common odontogenic cyst and is associated with a non-vital tooth.

A. Etiology and pathogenesis

• Pulpal necrosis, commonly due to caries or trauma, leads to periapical inflammation.
• Inflammatory mediators stimulate the epithelial rests of Malassez in the periodontal ligament.
• Epithelial proliferation and cyst formation occur around the root apex.

B. Clinical features

• Often asymptomatic and slow-growing.
• May be discovered incidentally on a radiograph.
• Larger lesions can cause swelling or cortical expansion.
• Usually associated with a non-vital tooth.

C. Radiographic features

• Well-defined, round or oval radiolucency.
• Usually centered at the apex of the causative tooth.
• May have a corticated margin.
• Larger lesions may expand or displace nearby structures.

D. Histopathology

E. Treatment

• Root canal treatment if the tooth is restorable and can be retained.
• Extraction if the tooth is non-restorable or retention is not appropriate.
• Enucleation or apical surgery may be indicated for selected persistent or large lesions.

Exam pearl: Rushton bodies are classically associated with radicular cysts. Cholesterol clefts can contribute to a shimmering appearance of aspirated cyst contents.

💡Residual cyst

A residual cyst is a radicular cyst that remains in the jaw after extraction of the causative tooth.

MCQ tip: A periapical cystic lesion associated with a non-vital tooth suggests a radicular cyst; a similar lesion remaining after extraction suggests a residual cyst.

💡DEVELOPMENTAL ODONTOGENIC CYSTS

💡Dentigerous cyst (follicular cyst)

A dentigerous cyst surrounds the crown of an unerupted or impacted tooth and attaches near the cementoenamel junction (CEJ).

A. Clinical features

• Second most common odontogenic cyst in the source.
• Commonly associated with an impacted mandibular third molar.
• Other common sites include maxillary canines and maxillary third molars.
• May delay eruption, displace teeth or expand the jaw.
• Often asymptomatic until it becomes large or infected.

B. Radiographic features

• Well-defined, usually unilocular radiolucency.
• Encloses the crown of an unerupted tooth.
• Attaches around the CEJ.
• Large lesions may displace teeth or cause root resorption.

C. Histopathology

• Thin, non-keratinized stratified squamous epithelial lining.
• The lining may be only a few cell layers thick when non-inflamed.
• Inflammation can alter the appearance of the lining.

D. Complications

• Ameloblastoma may arise in association with a dentigerous cyst.
• Squamous cell carcinoma is a rare reported complication.

E. Treatment

• Enucleation with removal of the associated tooth when appropriate.
• Marsupialization or decompression may be considered for large lesions, particularly when preservation of developing teeth or adjacent structures is important.
• Submit the specimen for histopathological examination.

💡Eruption cyst

An eruption cyst is the soft-tissue counterpart of a dentigerous cyst. It develops over a tooth crown as the tooth erupts through the alveolar bone into the oral soft tissues.

💡Odontogenic keratocyst (OKC)

The odontogenic keratocyst is an odontogenic cyst known for its locally aggressive behavior and significant recurrence risk.

A. Origin and clinical features

• Derived from odontogenic epithelial remnants, commonly dental lamina remnants.
• Often occurs in the second to fourth decades of life.
• Posterior mandible, especially the ramus and angle, is a classic site.
• May grow extensively along the medullary cavity with relatively limited expansion.
• Can displace teeth and may recur after treatment.

B. Radiographic features

• Well-defined radiolucency.
• May be unilocular or multilocular.
• Often has a scalloped border.
• May extend along the mandible with less buccolingual expansion than expected for its size.
• Tooth displacement may occur; root resorption is not always prominent.

C. Histopathology

D. Why does OKC recur?

• Fragile lining can tear during surgical removal.
• Small satellite cysts may remain in the cyst wall.
• Residual odontogenic epithelial remnants may contribute to recurrence.

E. Treatment

• Enucleation with an appropriate adjunctive strategy, such as peripheral ostectomy or chemical cauterization in selected cases.
• Carnoy solution may be used according to the clinical setting and local protocol.
• Decompression or marsupialization followed by enucleation may be appropriate for selected large lesions.
• Long-term clinical and radiographic follow-up is important.

💡Gorlin syndrome (nevoid basal cell carcinoma syndrome)

Gorlin syndrome is an inherited condition associated with multiple OKCs and basal cell carcinomas.

A. Genetics

• Usually autosomal dominant.
• Classically associated with a pathogenic variant in PTCH1, affecting Hedgehog signaling.
• PTCH1 is located on chromosome 9q.

B. Clinical features

C. Management

• Long-term surveillance for new or recurrent jaw cysts.
• Regular dermatological assessment.
• Specialist evaluation for associated skeletal and neurological manifestations.
• Conservative OKC management when appropriate, with recurrence surveillance.

MCQ tip: Multiple OKCs in a young patient + calcified falx cerebri + basal cell carcinomas = Gorlin syndrome.

💡Lateral periodontal cyst

A lateral periodontal cyst is a developmental odontogenic cyst arising beside the root of a tooth, classically in the mandibular canine–premolar region.

Clinical and radiographic features

• Usually asymptomatic.
• Located lateral to the root of a vital tooth.
• Well-defined, round or oval radiolucency.
• The botryoid variant is multilocular or grape-like and has a greater tendency to recur.

Histology

• Thin, non-keratinized epithelial lining.
• Focal epithelial thickenings may be present.
• Glycogen-rich clear cells may be seen in the lining.

Treatment

• Enucleation.
• Preserve the associated tooth if it remains healthy and vital.
• Follow-up is particularly important for the botryoid variant.

Exam tip: A small lateral radiolucency next to a vital mandibular premolar suggests a lateral periodontal cyst, not a radicular cyst.

💡Gingival cyst

Gingival cysts are developmental odontogenic cysts found in the soft tissues of the gingiva.

Important distinction: Epstein pearls occur on the midline or palatal mucosa; Bohn nodules are classically described on the lateral palate or alveolar regions. These newborn cysts are benign and typically resolve spontaneously.

💡Glandular odontogenic cyst (GOC)

GOC is a rare developmental odontogenic cyst that may behave aggressively and has a tendency to recur.

Clinical features

• Commonly involves the anterior mandible.
• May grow considerably and cause cortical expansion.
• Can be multilocular.

Histopathology

Treatment

• Enucleation may be considered for smaller lesions.
• Larger, recurrent or more aggressive lesions may require more extensive surgery.
• Long-term follow-up is important because recurrence can be substantial.

FCPS tip: Anterior mandibular cyst + mucous cells + intraepithelial microcysts = glandular odontogenic cyst.

💡Orthokeratinized odontogenic cyst (OOC)

OOC is a distinct developmental odontogenic cyst that must be differentiated from OKC.

MCQ tip: Orthokeratinized lining + granular cell layer + much lower recurrence = OOC.

💡NON-ODONTOGENIC CYSTS

💡Nasopalatine duct cyst (incisive canal cyst)

The nasopalatine duct cyst is the most common non-odontogenic cyst of the jaws in the source.

A. Origin and location

• Develops from epithelial remnants of the embryonic nasopalatine duct.
• Located in the anterior maxillary midline.
• Usually lies in the incisive canal, between the roots of the maxillary central incisors.

B. Clinical and radiographic features

The heart shape may result from superimposition of the anterior nasal spine or surrounding anatomical structures.

C. Treatment

• Enucleation when indicated.
• Adjacent teeth usually do not require extraction or endodontic treatment if they remain vital and healthy.

FCPS tip: Heart-shaped radiolucency between vital maxillary central incisors = nasopalatine duct cyst.

Important differential diagnosis: A radicular cyst associated with a non-vital central incisor may mimic a nasopalatine duct cyst. Check pulp vitality and lesion location.

💡Nasolabial cyst

The nasolabial cyst is a soft-tissue cyst in the nasolabial fold. Unlike most jaw cysts, it does not primarily arise within bone.

Clinical features

• Swelling in the soft tissues lateral to the nasal midline.
• Located beneath the nasal ala in the nasolabial fold.
• May elevate the nasal ala or obliterate the nasolabial fold.
• Radiographs of the jaw may show no intraosseous lesion.

Origin

It is thought to arise from epithelial remnants associated with embryonic nasolacrimal duct development.

Treatment

• Surgical excision through an appropriate approach, commonly an intraoral approach.

MCQ tip: Nasolabial cyst = extraosseous soft-tissue swelling near the nasal ala, often with no bony radiographic abnormality.

💡PSEUDOCYSTS OF THE JAWS

Pseudocysts are lesions that resemble cysts clinically or radiographically but lack a true epithelial lining.

💡Simple bone cyst (traumatic bone cyst)

Also called a traumatic or hemorrhagic bone cyst, this is an intraosseous cavity without an epithelial lining.

Features

• Often occurs in young patients.
• Frequently involves the mandible.
• May be asymptomatic and discovered incidentally.
• Classically scallops between the roots of teeth.
• Associated teeth are often vital.

Diagnosis and management

• Surgical exploration is commonly used to confirm the diagnosis.
• The cavity may be empty or contain a small amount of fluid or blood.
• Curettage of the cavity can stimulate bleeding and healing.
• Follow-up radiographs assess bone regeneration.

MCQ tip: Empty or fluid-poor cavity + scalloping between roots + no epithelial lining = simple bone cyst.

💡Aneurysmal bone cyst

An aneurysmal bone cyst is an expansile, blood-filled bone lesion.

Exam tip: A rapidly expanding, blood-filled lesion is suggestive of an aneurysmal bone cyst. It is not necessarily a true cyst.

The Stafne bone defect is a developmental or anatomical concavity of the mandible, usually containing salivary gland tissue.

Features

A lingual mandibular depression may occur in other locations, but the classic Stafne defect is posterior and inferior to the mandibular canal.

FCPS tip: Incidental radiolucency below the inferior alveolar canal in the posterior mandible = Stafne bone defect.

💡COMPARISON TABLE: JAW CYSTS

This is the main table to revise before FCPS.

💡EPITHELIAL ODONTOGENIC TUMORS

CLASSIFICATION

High-yield distinction:

• Most common odontogenic tumor overall: Odontoma — a hamartoma, not a true neoplasm.
• Most common clinically significant odontogenic tumor: Ameloblastoma — a true, locally aggressive neoplasm.

💡Ameloblastoma

Ameloblastoma is a benign epithelial odontogenic neoplasm that is locally aggressive and can recur if inadequately treated.

Clinical features

• Most common clinically significant odontogenic tumor.
• Usually occurs in adults aged approximately 30–50 years.
• Around 80% of cases occur in the posterior mandible, particularly the molar–ramus region.
• Slow-growing, often painless jaw swelling.
• May cause facial asymmetry, cortical expansion and tooth displacement.

Radiographic features

• Typically multilocular radiolucency.
• Classic appearances include soap-bubble and honeycomb patterns.
• Root resorption and tooth displacement may occur.
• A unilocular appearance is also possible, particularly in some variants.

Histopathology

The source emphasizes the follicular pattern as the commonest histological pattern.

Variants

• Conventional ameloblastoma: Locally aggressive, with substantial recurrence risk if inadequately treated.
• Unicystic ameloblastoma: Often occurs in younger patients and may have a better prognosis in selected cases.
• Peripheral ameloblastoma: Occurs in soft tissue rather than primarily within bone.

Treatment

• Conventional ameloblastoma commonly requires resection with appropriate margins.
• Margin of approximately 1–1.5 cm; the exact approach depends on tumor extent and specialist planning.
• Curettage alone has a higher recurrence risk in conventional lesions.
• Selected unicystic lesions may be managed more conservatively, depending on histology and extent.
• Long-term follow-up is essential.

FCPS exam pearl: Reverse nuclear polarity + stellate-reticulum-like centers + posterior mandibular soap-bubble radiolucency = ameloblastoma.

💡Adenomatoid odontogenic tumor (AOT)

AOT is a benign odontogenic epithelial lesion, generally regarded as a hamartomatous or tumor-like lesion with very limited recurrence after conservative removal.

Clinical features

• Classically occurs in young patients, especially females.
• Usually involves the anterior maxilla.
• Frequently associated with an unerupted canine.
• The source mnemonic is the “two-thirds tumor.”

Radiographic features

• Well-defined, usually unilocular radiolucency.
• May surround an unerupted tooth.
• Fine calcifications may create a snowflake appearance.
• The lesion may extend apically beyond the CEJ, unlike the typical attachment pattern of a dentigerous cyst.

Treatment

• Conservative enucleation.
• Recurrence is very uncommon.

FCPS tip: Young female + anterior maxilla + impacted canine + fine snowflake calcifications = AOT.

💡Calcifying epithelial odontogenic tumor (CEOT)

Also called the Pindborg tumor, CEOT is a rare epithelial odontogenic neoplasm that can show local aggression.

Clinical features

• Usually occurs in middle-aged adults.
• Commonly involves the posterior mandible.
• May be associated with an impacted tooth.
• Produces a slowly enlarging jaw swelling.

Radiographic features

• Mixed radiolucent–radiopaque lesion.
• Scattered calcifications may produce a driven-snow appearance.

Histopathology

Treatment

• Surgical removal or resection according to lesion extent.
• Local recurrence is possible, so follow-up is needed.

FCPS tip: Pindborg tumor = amyloid-like material + Liesegang ring calcifications + driven-snow radiograph.

💡Squamous odontogenic tumor

A rare, generally benign epithelial odontogenic tumor.

• Often occurs in the alveolar process.
• May present as a radiolucency between or near tooth roots.
• Can be multilocular.
• Treatment is usually conservative surgical excision.

💡EPITHELIAL–MESENCHYMAL ODONTOGENIC TUMORS

💡Ameloblastic fibroma

Ameloblastic fibroma is a true mixed odontogenic tumor containing both neoplastic odontogenic epithelium and ectomesenchymal tissue.

Clinical features

• More common in children and adolescents.
• Usually affects the posterior mandible.
• Frequently associated with an unerupted tooth.
• May present as painless swelling or delayed tooth eruption.

Radiographic features

• Well-defined radiolucency.
• Usually unilocular, although larger lesions may be multilocular.
• May be associated with an impacted tooth.

Histopathology

• Odontogenic epithelial cords and islands.
• Cellular, primitive ectomesenchymal tissue resembling dental papilla.
• Both components are present in the lesion.

Treatment

• Conservative surgical removal is commonly considered.
• Follow-up is important because recurrence can occur.
• Ameloblastic fibrosarcoma is a malignant counterpart in which the mesenchymal component becomes malignant.

FCPS tip: Child or adolescent + posterior mandibular radiolucency associated with an unerupted tooth + both epithelial and ectomesenchymal components = ameloblastic fibroma.

💡MESENCHYMAL / ECTOMESENCHYMAL ODONTOGENIC TUMORS

💡Odontogenic myxoma

Odontogenic myxoma is a benign mesenchymal odontogenic tumor that can be locally aggressive and has a significant recurrence risk after conservative treatment.

Clinical features

• Often occurs in young adults.
• Most commonly affects the posterior mandible.
• May produce painless expansion of the jaw.
• Can displace teeth and expand cortical plates.

Radiographic features

• Multilocular radiolucency.
• May show honeycomb, tennis-racket or soap-bubble patterns.
• Thin internal septa may create angular or straight-line patterns.

Histopathology

• Abundant loose myxoid extracellular matrix.
• Stellate and spindle-shaped cells.
• Sparse collagen in the myxoid stroma.

Treatment

• Surgical excision with adequate clearance according to lesion size and behavior.
• Recurrence may occur, especially following conservative curettage.
• Long-term follow-up is advisable.

FCPS tip: Multilocular posterior mandibular radiolucency + tennis-racket septa + myxoid stroma = odontogenic myxoma.

💡Cementoblastoma

Cementoblastoma is a benign cementum-forming tumor that is characteristically fused to the root of a tooth.

Clinical features

• Usually affects young patients, often under 25 years.
• Commonly involves mandibular premolars or first molars.
• The associated tooth is generally vital.
• May cause pain, swelling and cortical expansion.

Radiographic features

• Well-defined radiopaque mass fused to the tooth root.
• Surrounded by a radiolucent rim.
• Root outline may be obscured by fusion of the lesion with the root.

Treatment

• Removal of the tumor with the associated tooth is commonly performed.
• Tooth preservation may be considered in selected cases if complete removal and appropriate management are feasible.
• Recurrence can occur if the lesion is incompletely removed.

FCPS tip: Radiopaque mass fused to the root of a vital tooth + radiolucent rim = cementoblastoma.

💡Cemento-ossifying fibroma

Cemento-ossifying fibroma is a benign fibro-osseous neoplasm, typically well-demarcated and expansile.

Clinical features

• Commonly affects the posterior mandible.
• Often occurs in young to middle-aged adults.
• More frequent in women.
• Presents as slowly progressive, usually painless swelling.

Radiographic features

The appearance changes with mineralization:

Histology

• Fibrous connective tissue containing mineralized material.
• Bone and cementum-like deposits may be present.

Treatment

• Enucleation or surgical excision, depending on the lesion.
• Its well-defined boundary often facilitates removal.
• Follow-up is indicated to assess healing and detect recurrence.

FCPS tip: Well-circumscribed, expansile fibro-osseous lesion = cemento-ossifying fibroma; unlike fibrous dysplasia, it tends to separate from surrounding bone.

💡COMPARISON TABLE

All major odontogenic tumors

💡Mesenchymal Neoplasms

💡Benign Neural Tumours

A. Neurofibroma

Definition: A benign peripheral nerve sheath tumour composed of a mixture of Schwann cells, perineurial-like cells and fibroblastic elements.

Origin and pathology

• Arises from peripheral nerves and their associated supporting cells.
• Unlike schwannoma, the tumour is not composed exclusively of Schwann cells.
• Usually unencapsulated, allowing it to intermingle with the parent nerve.

Clinical features

• Soft, sessile or pedunculated swelling.
• Usually skin-coloured or similar in colour to the surrounding oral mucosa.
• Often presents as a small, painless nodule.
• Multiple lesions suggest an underlying neurofibromatosis syndrome.

Common oral sites

• Tongue.
• Buccal mucosa.
• Lips.
• Palate.

Solitary vs multiple neurofibromas

💡Neurofibromatosis type 1 (NF1 — von Recklinghausen disease)

Characteristic findings include:

• Café-au-lait macules.
• Axillary or inguinal freckling.
• Lisch nodules of the iris.
• Multiple neurofibromas.
• Plexiform neurofibromas.

Histopathology

• Wavy spindle-shaped nuclei.
• Loose myxoid stroma.
• Mast cells may be present.
• Typically unencapsulated.

Malignant transformation

• Approximately 5% lifetime risk of malignant peripheral nerve sheath tumour (MPNST).
• Rapid enlargement, new persistent pain or neurological deficit in a known neurofibroma raises concern for malignant transformation.

Treatment: Surgical excision for symptomatic or diagnostically uncertain lesions. Recurrence is generally uncommon after complete removal of a solitary lesion.

💡B. Schwannoma (Neurilemmoma)

Definition: A benign peripheral nerve sheath tumour derived almost exclusively from Schwann cells.

Clinical features

• Slow-growing, smooth, firm submucosal nodule.
• Usually painless.
• Well-circumscribed and encapsulated.
• Grows eccentrically from the nerve, displacing the nerve fibres rather than diffusely incorporating them.

Common oral sites

• Tongue — most common oral site.
• Floor of mouth.
• Palate.
• Lip.

Histopathology

Two characteristic patterns are seen.

Antoni A pattern

• Densely cellular areas.
• Compact spindle cells.
• Nuclear palisading.
• Verocay bodies formed by parallel rows of nuclei separated by anuclear zones.

Antoni B pattern

• Loosely arranged cells.
• Hypocellular, myxoid areas.
• Less organized architecture than Antoni A.

Immunohistochemistry: Strong S-100 protein positivity supports Schwann cell differentiation.

Treatment: Surgical excision. Recurrence is uncommon after complete removal, and the nerve can often be preserved.

Plexiform neurofibroma

• A diffuse, tortuous proliferation involving multiple nerve fascicles.
• May produce a characteristic “bag of worms” appearance.
• Strongly associated with NF1 and considered pathognomonic in the appropriate clinical setting.
• Carries a significant risk of malignant peripheral nerve sheath tumour transformation.

Clinical pearl: Rapid enlargement or new pain in a plexiform neurofibroma should prompt urgent assessment for MPNST.

💡Benign Mesenchymal Tumours

💡A. Lipoma

Definition: A benign neoplasm composed of mature adipocytes.

Clinical features

• Soft, yellowish, well-circumscribed swelling.
• Usually painless and slow-growing.
• May be sessile or pedunculated.

Common oral sites

• Buccal mucosa — most common.
• Tongue.
• Floor of mouth.
• Lips.

Histopathology

• Mature adipocytes arranged in lobules.
• Fibrous connective tissue capsule or septa.
• No significant cellular atypia in a conventional lipoma.

Variants

• Fibrolipoma.
• Spindle cell lipoma.
• Angiolipoma.
• Intramuscular lipoma.

Treatment: Simple surgical excision. Recurrence is uncommon after complete removal, although infiltrative variants may recur more frequently.

💡B. Granular Cell Tumour

Definition: A benign soft tissue neoplasm of Schwann cell origin, characterized by abundant granular cytoplasm.

Clinical features

• Usually a firm, sessile, painless nodule.
• Commonly measures approximately 1–2 cm.
• Normal mucosal colour or slightly yellowish appearance.
• The tongue is the most common oral site, accounting for approximately 65% of oral cases.
• May occur on the dorsal or lateral tongue.

Histopathology

• Large polygonal cells with abundant eosinophilic granular cytoplasm.
• Granules contain lysosomal material and are PAS-positive.
• S-100 positivity supports Schwann cell origin.
• Overlying epithelium may show marked pseudoepitheliomatous hyperplasia.

Important diagnostic trap: The epithelial hyperplasia may mimic squamous cell carcinoma on a superficial biopsy. The underlying lesion must be sampled adequately to distinguish a granular cell tumour from true SCC.

Treatment: Conservative surgical excision.

💡C. Congenital Granular Cell Epulis (Congenital Epulis)

Definition: A congenital soft tissue lesion occurring in newborns, typically on the alveolar ridge.

Clinical features

• Present at birth.
• Strong female predominance, approximately 8:1.
• More commonly affects the anterior maxillary alveolar ridge than the mandible.
• Appears as a pink, pedunculated mass projecting from the gingiva.
• Large lesions may interfere with feeding or, rarely, respiration.

Histopathology

• Large granular cells resembling those of a granular cell tumour.
• S-100 negative, unlike the conventional granular cell tumour.
• This immunohistochemical distinction is important for diagnosis.

Treatment

• Simple excision if feeding, respiration or other functions are affected.
• Spontaneous regression may occur.
• Recurrence is uncommon, unlike incompletely excised conventional granular cell tumours.

Granular cell tumour vs congenital epulis

💡Vascular Tumours

💡A. Hemangioma

Definition: A benign vascular tumour characterized by endothelial proliferation. Infantile hemangioma is a common vascular tumour of infancy.

Clinical features

• Usually appears shortly after birth.
• Initially undergoes rapid proliferative growth, followed by gradual involution.
• Classically red or blue, soft and compressible.
• Blanches on pressure — positive diascopy.
• Common oral sites include the lips, tongue, buccal mucosa and palate.
• Strawberry hemangioma is the classic superficial infantile form.

Histopathology and investigations

• Proliferating endothelial-lined vascular channels.
• GLUT-1 positive in typical infantile hemangioma.
• Diascopy helps demonstrate that the lesion contains compressible blood-filled vessels.

Natural history

1. Appears shortly after birth.
2. Enters a proliferative phase with rapid growth.
3. Gradually involutes, often substantially by age 5–7 years.

Management

Critical safety pearl: Do not biopsy or extract a tooth near a suspected vascular lesion without appropriate assessment. Unrecognized vascular lesions may cause life-threatening hemorrhage.

💡Lymphangioma

Definition: A developmental malformation of lymphatic vessels rather than a conventional vascular neoplasm.

Clinical features

• Usually present at birth or during early childhood.
• Does not characteristically involute spontaneously.
• Soft, diffuse and non-tender.
• Commonly affects the tongue, producing macroglossia.
• Surface may have numerous small, translucent or vesicle-like projections, sometimes described as frog-egg or pebble-like.

Histopathology

• Dilated lymphatic channels lined by flattened endothelial cells.
• Lumina contain lymph rather than blood.
• GLUT-1 negative, helping distinguish it from infantile hemangioma.

Cystic hygroma

• A macrocystic form of lymphatic malformation.
• Commonly affects the posterior triangle of the neck.
• May produce a large, soft, transilluminant swelling.
• Extensive lesions can compress the airway.

Treatment

• Surgical excision where feasible.
• Complete removal may be difficult because the lesion infiltrates surrounding tissues.
• Sclerotherapy, including OK-432 where available and appropriate, may be used.
• Recurrence is common after incomplete treatment.

💡Hemangioma vs lymphangioma

Exam pearl: Blanching suggests hemangioma; a diffuse tongue enlargement with a pebbly, vesicle-like surface suggests lymphangioma.

Sturge–Weber Syndrome (Encephalotrigeminal Angiomatosis)

Definition: A sporadic neurocutaneous disorder involving capillary-venous malformations of the face, leptomeninges and sometimes the eye.

Clinical triad and features

Genetics

• Associated with a somatic activating GNAQ mutation.
• It is generally sporadic rather than inherited.

Dental significance

• Ipsilateral gingival hemangiomatous enlargement may bleed significantly during dental procedures.
• Assess the extent of vascular involvement before surgery.
• Plan treatment carefully to minimize hemorrhage.

Exam pearl: Port-wine stain + seizures + intracranial tram-track calcifications strongly suggests Sturge–Weber syndrome.

💡Malignant Soft Tissue Tumours

💡A. Rhabdomyosarcoma

Definition: A malignant tumour showing skeletal muscle differentiation.

High-yield fact: Rhabdomyosarcoma is the most common soft tissue sarcoma of childhood, particularly in children younger than 10 years.

Origin and sites

• Arises from primitive mesenchymal cells showing skeletal muscle differentiation.
• Common head and neck sites include the orbit, paranasal sinuses, nasopharynx and oral cavity.
• May present in areas where mature skeletal muscle is not prominent.

Histological types

Clinical features

• Rapidly enlarging mass.
• May resemble a dental abscess, polyp or other benign soft tissue lesion.
• Symptoms depend on site and may include pain, obstruction or functional impairment.

Histopathology and immunohistochemistry

• Small round blue cells may be seen.
• Cross-striations may be present but are not always identifiable.
• Desmin and myogenin positivity support skeletal muscle differentiation.

Treatment

• Multimodal management, usually involving:
• Surgery when feasible.
• Chemotherapy.
• Radiotherapy according to tumour type, site and stage.

Prognosis

• Depends on histological subtype, tumour site, stage and response to therapy.
• 70% five-year survival for favourable sites.

Exam pearl: Childhood soft tissue sarcoma + desmin and myogenin positivity = rhabdomyosarcoma.

💡B. Fibrosarcoma

Definition: A malignant mesenchymal tumour composed of fibroblastic cells producing collagen.

Clinical features

• Usually affects adults, with ages 30–60 years.
• Common oral sites include the mandible, particularly periosteal regions, buccal mucosa and tongue.
• Presents as a firm, often painless, slowly enlarging mass.
• Can resemble a benign fibroma clinically.

Histopathology

• Interlacing bundles of spindle-shaped tumour cells.
• Classic herringbone pattern, with fascicles crossing in opposing directions.
• Cellular atypia and mitotic activity vary with tumour grade.

Treatment

• Wide surgical excision with adequate margins.
• Radiotherapy may be considered for unresectable disease or selected cases.

Prognosis

• Intermediate and dependent on grade, site, margins and extent of disease.
• High-grade lesions behave more aggressively.

Exam pearl: A herringbone arrangement of malignant spindle cells is characteristic of fibrosarcoma.

💡C. Kaposi Sarcoma

Definition: A vascular spindle-cell neoplasm associated with human herpesvirus 8 (HHV-8).

Etiology and types

HHV-8 is essential to the development of Kaposi sarcoma.

Oral manifestations

• May be the first manifestation of HIV-associated disease.
• The palate is a particularly common oral site.
• Gingiva may also be affected.
• Lesions can be multiple and may ulcerate in advanced disease.

Clinical features

• Flat or nodular red-purple, blue or brown lesions.
• May be painless initially.
• Colour results from vascular proliferation and extravasated erythrocytes.

Histopathology

• Spindle-shaped tumour cells.
• Slit-like vascular spaces.
• Extravasated red blood cells.
• Hyaline globules may be present.
• HHV-8 immunohistochemistry supports diagnosis.

Treatment

Prognosis

• HIV-associated Kaposi sarcoma may regress with immune restoration after effective antiretroviral therapy.
• Prognosis depends on immune status, extent and visceral involvement.

Exam pearls

• Causative virus: HHV-8.
• Common oral site: hard palate.
• AIDS-associated Kaposi sarcoma is strongly associated with immunosuppression.
• ART is a central component of management in HIV-associated disease.

💡Other Soft Tissue Lesions

💡A. Myxoma

Definition: A rare benign soft tissue lesion characterized by abundant myxoid (mucopolysaccharide-rich) extracellular matrix.

Important distinction: Soft tissue myxoma is different from odontogenic myxoma, which occurs within the jawbones.

Clinical features

• Rare in the oral cavity.
• Usually poorly circumscribed.
• May present as a soft tissue mass.

Histopathology

• Sparse spindle-shaped or stellate cells.
• Abundant loose myxoid (mucoid) stroma.
• Poorly defined margins may make complete excision difficult.

Treatment: Surgical excision. Follow-up is appropriate if removal is incomplete.

💡B. Leiomyoma

Definition: A benign neoplasm of smooth muscle origin.

Origin and sites

• Derived from smooth muscle cells.
• Rare in the oral cavity because normal oral mucosa contains little smooth muscle.
• When present, it commonly arises from the smooth muscle of blood vessel walls; these vascular lesions include angioleiomyoma.

Clinical features

• Usually a slow-growing, firm nodule.
• May be painless.
• Clinical appearance is nonspecific.

Treatment: Surgical excision; prognosis is generally excellent.

💡Comparison Tables

💡Neurofibroma vs Schwannoma

💡Vascular lesions: Hemangioma vs Lymphangioma

💡Granular lesions: Granular Cell Tumour vs Congenital Epulis

💡Malignant soft tissue tumours