Mastication muscle cysts are abnormal, fluid-filled sacs that develop within or adjacent to the muscles responsible for chewing (the masseter, temporalis, medial pterygoid, and lateral pterygoid), collectively known as the masticatory muscles. These cysts arise when a pocket of fluid becomes encapsulated by tissue, which can lead to swelling, discomfort, and impaired jaw function. They are distinct from abscesses (infectious collections of pus) and tumors (solid growths), and may be congenital, developmental, parasitic, or acquired through trauma or inflammation PMCPMC.
Anatomy of the Masticatory Muscles
The masticatory muscles are housed in the paired masticator spaces—deep fascial compartments on each side of the face—extending from the angle of the mandible up to the parietal region SpringerOpenPMC.
Structure & Location:
The masticator space contains four paired muscles of mastication (masseter, temporalis, medial pterygoid, lateral pterygoid), the ramus and posterior body of the mandible, branches of the mandibular (V₃) nerve, and accompanying vessels Radiopaedia.Origin & Insertion:
Masseter: Originates from the zygomatic arch; inserts on the angle and lateral ramus of the mandible WikipediaRadiopaedia.
Temporalis: Arises from the temporal fossa and fascia; converges to insert on the coronoid process and anterior ramus of the mandible WikipediaKenhub.
Medial Pterygoid: Originates from the medial surface of the lateral pterygoid plate and palatine bone; inserts on the medial ramus of the mandible Wikipedia.
Lateral Pterygoid: Has two heads—superior head from the greater wing of the sphenoid, inferior head from the lateral pterygoid plate; both insert on the pterygoid fovea of the mandible Wikipedia.
Blood Supply:
Supplied primarily by branches of the maxillary artery: the deep temporal arteries (temporalis), masseteric artery (masseter), and pterygoid branches (pterygoids) Wikipedia.Nerve Supply:
All four muscles receive motor innervation from the mandibular branch (V₃) of the trigeminal nerve, with sensory fibers carried by the same division PMC.Functions (key actions):
Elevation of the mandible (closing the jaw)
Depression of the mandible (opening, via lateral pterygoid)
Protrusion (moving jaw forward)
Retraction (pulling jaw backward)
Lateral excursion (side-to-side grinding)
Stabilization of the temporomandibular joint during speech and swallowing Wikipedia.
Types of Mastication Muscle Cysts
Cysts in the masticatory muscles can be classified by origin and histology:
Epidermoid cysts (epidermal inclusion)
Dermoid cysts (contain skin adnexa)
Lymphatic malformations (cystic hygromas)
Parasitic cysts (cysticercosis, hydatid)
Mucoid inclusion cysts (following trauma or surgery)
Synovial cysts (near the temporomandibular joint)
Branchial cleft cysts (rarely extending into masticator space)
Retention cysts (from obstructed salivary duct)
Heterotopic cysts (developmental ectodermal rests)
Post-traumatic pseudocysts ScienceDirectMedscape.
Causes
While the precise trigger depends on cyst type, common etiologies include:
Sequestration of epidermal rests during embryogenesis
Obstruction of pilosebaceous units
Traumatic implantation of epithelial elements
Surgical introduction of skin cells
Branchial arch fusion defects
Occlusion of salivary ducts
Chronic inflammation of adjacent tissue
Cystic degeneration within tumors
Parasitic infection (Taenia solium, Echinococcus)
Lymphatic channel malformation
Mucocele formation from minor salivary glands
Implantation during dental extraction
Iatrogenic injury (e.g., biopsy tract)
HPV infection (palmoplantar analogues)
UV-induced damage in dermoid variants
Repeated minor trauma (bruxism, chewing hard foods)
Idiopathic proliferation of dermal elements
Post-crush injury (car door, sports)
Embryonic ectodermal rest misplacement
Postoperative sequelae (e.g., cosmetic surgery) MedscapeJKSR.
Symptoms
Patients with mastication muscle cysts may report:
Localized facial swelling
Gradual onset of a firm lump
Mild to moderate pain on chewing
Restricted mouth opening (trismus)
Facial asymmetry
Tenderness on palpation
Audible clicking near TMJ (if joint involved)
Numbness or tingling (if nerve compression)
Redness of overlying skin (if inflamed)
Fluctuant mass on examination
Dysphagia (if extending medially)
Altered bite alignment
Bruising (if recent trauma)
Visible central punctum (epidermoid)
Fistula formation (rare)
Drainage of keratinous material
Serous or purulent discharge
Fever (when secondarily infected)
Headache or earache
Diagnostic Tests
Accurate diagnosis typically involves multimodal evaluation:
Clinical examination and history
Ultrasound imaging (cystic vs. solid)
Doppler ultrasound (vascular flow)
CT scan (bony involvement)
MRI (soft tissue delineation)
Fine-needle aspiration cytology (FNAC)
Core needle biopsy
Histopathological examination
Serologic tests for parasites (ELISA)
Stool ova and parasite exam (cysticercosis)
Hydatid serology (Echinococcus)
Contrast arthrography (TMJ cysts)
Sialography (salivary duct cysts)
PET scan (rule out neoplasm)
Blood tests (CBC, inflammatory markers)
Bacterial culture (if infected)
Fistulography (if sinus tract)
Ultrasound-guided aspiration
Electromyography (nerve involvement)
Intraoral endoscopy (deep lesions) SpringerOpenRSNA Publications.
Non-Pharmacological Treatments
Conservative and minimally invasive approaches can relieve symptoms and reduce cyst size:
Clinical observation for small, asymptomatic cysts
Warm compresses to promote drainage
Cold packs for acute swelling
Ultrasound therapy to soften contents
Manual lymphatic drainage
Jaw stretching and physiotherapy
Transcutaneous electrical nerve stimulation (TENS)
Acupuncture for pain relief
Low-level laser therapy (LLLT)
Cryotherapy for superficial lesions
Fine-needle aspiration
Ultrasound-guided catheter drainage
Endoscopic-assisted drainage
Suture-guided marsupialization
Manual expression under local anesthesia
Myofascial release massage
Dietary modifications (soft diet)
Avoidance of hard or sticky foods
Behavior modification (avoid bruxism)
Dental splints to relieve stress
Orthotic appliances for TMJ
Hyperbaric oxygen therapy
Postural training and ergonomic advice
Speech therapy (if swallowing affected)
Behavioral therapy for parafunctional habits
Heat-packs combined with gentle massage
Ultrasound-guided ethanol instillation (for lymphatic)
Endoscopic marsupialization
Guided radiofrequency ablation
Image-guided cryoablation ScienceDirectRadiopaedia.
Drugs
Pharmacotherapy targets pain, inflammation, infection, or parasitic causes:
Ibuprofen (NSAID for pain/inflammation)
Acetaminophen (analgesic)
Naproxen (NSAID)
Diclofenac (NSAID)
Prednisone (systemic corticosteroid)
Amoxicillin–clavulanate (broad-spectrum antibiotic)
Clindamycin (anaerobic coverage)
Cephalexin (first-generation cephalosporin)
Metronidazole (anaerobic bacteria)
Albendazole (anti-helminthic for cysticercosis)
Praziquantel (treatment for tapeworm cysts)
Ivermectin (parasiticides)
Sirolimus (mTOR inhibitor for lymphatic malformations)
OK-432 (Picibanil) (sclerosing agent)
Bleomycin (sclerotherapy adjunct)
Doxycycline (sclerosing and antibiotic)
Prednisolone mouthwash (topical inflammation)
Triptans (if headache associated)
Muscle relaxants (e.g., cyclobenzaprine)
Surgeries
Surgical management is reserved for persistent, large, or complicated cysts:
Enucleation (complete excision)
Marsupialization (creating a permanent opening)
Peripheral ostectomy (removing bone margins)
Endoscopic-assisted cyst removal
Laser excision (CO₂ laser)
Cryosurgical excision
Open surgical drainage with drain placement
CT-guided percutaneous drainage
Flap reconstruction (if significant tissue loss)
Bone grafting (post-cystectomy defect repair) RadiopaediaScienceDirect.
Prevention Strategies
Preventive measures can lower the risk of cyst formation:
Maintain excellent oral hygiene
Attend regular dental check-ups
Avoid facial trauma (use protective gear)
Cook pork thoroughly (prevent cysticercosis)
Practice deworming protocols in endemic areas
Seek early treatment of odontogenic infections
Use proper technique in oral surgery and injections
Manage bruxism with night guards
Limit UV exposure (dermoid prevention)
Educate patients on avoiding self-trauma to lesions MedlinePlusJKSR.
When to See a Doctor
Seek professional evaluation if you experience:
A firm or growing lump persisting beyond two weeks
Increasing pain during chewing or at rest
Progressive trismus (limited mouth opening)
Signs of infection (fever, redness, pus)
Nerve symptoms (numbness, tingling)
Rapid enlargement or hardening of the mass
Difficulty swallowing or breathing
Any facial asymmetry that worsens over time SpringerOpenPMC.
Frequently Asked Questions
What exactly is a mastication muscle cyst?
A mastication muscle cyst is a benign, fluid-filled sac that forms within one of the muscles used for chewing. It differs from an abscess by lacking active infection and from a tumor by being fluid-filled rather than solid PMC.How common are these cysts?
They are rare. Intramuscular epidermoid cysts in the masticator space are uncommon, with only isolated case reports in the literature ScienceDirect.Can mastication muscle cysts turn cancerous?
Almost never. These cysts are benign; malignant transformation is exceedingly rare and typically only reported in epidermoid cysts with long-standing inflammation ScienceDirect.What is the difference between an epidermoid and dermoid cyst?
Epidermoid cysts contain only skin cells, whereas dermoid cysts also include skin appendages (hair follicles, sebaceous glands) within their lining Radiopaedia.Are they painful?
Many are painless but can become tender if they enlarge or become secondarily inflamed or infected PMC.How are they diagnosed?
Diagnosis is based on clinical exam, imaging (ultrasound, CT, MRI), and often fine-needle aspiration or biopsy RSNA Publications.Can these cysts resolve on their own?
Small, asymptomatic cysts may remain stable and require only observation; larger or symptomatic lesions usually need intervention PMC.What are the risks of leaving a cyst untreated?
Potential for growth, discomfort, trismus, secondary infection, or damage to surrounding structures Medscape.Is surgery always necessary?
Not always—many cysts can be managed conservatively or with minimally invasive drainage if small and uninfected ScienceDirect.How long is recovery after surgery?
Recovery typically takes 1–2 weeks, with mild swelling and pain managed by NSAIDs; full return of jaw function may take up to a month NCBI.Can these cysts recur after excision?
Recurrence is uncommon if the cyst is completely removed; incomplete excision raises the risk of recurrence Synapse.Do they affect eating or speaking?
Large cysts or those causing trismus can interfere with chewing or speech, which usually resolves after treatment PMC.Are parasitic cysts in these muscles preventable?
Yes—proper cooking of meat, good hygiene, and deworming in endemic areas can reduce risk MedlinePlus.What specialists treat mastication muscle cysts?
Oral and maxillofacial surgeons, ENT specialists, or head and neck radiologists typically manage these lesions SpringerOpen.Can physical therapy help?
Yes—physiotherapy and jaw exercises can improve mouth opening and reduce discomfort both before and after any procedural intervention PMC.
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Last Updated: April 24, 2025.
