Mastication Muscle Cysts

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.

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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):

  1. Elevation of the mandible (closing the jaw)

  2. Depression of the mandible (opening, via lateral pterygoid)

  3. Protrusion (moving jaw forward)

  4. Retraction (pulling jaw backward)

  5. Lateral excursion (side-to-side grinding)

  6. Stabilization of the temporomandibular joint during speech and swallowing Wikipedia.

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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.

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Causes

While the precise trigger depends on cyst type, common etiologies include:

1. Sequestration of epidermal rests during embryogenesis

2. Obstruction of pilosebaceous units

3. Traumatic implantation of epithelial elements

4. Surgical introduction of skin cells

5. Branchial arch fusion defects

6. Occlusion of salivary ducts

7. Chronic inflammation of adjacent tissue

8. Cystic degeneration within tumors

9. Parasitic infection (Taenia solium, Echinococcus)

10. Lymphatic channel malformation

11. Mucocele formation from minor salivary glands

12. Implantation during dental extraction

13. Iatrogenic injury (e.g., biopsy tract)

14. HPV infection (palmoplantar analogues)

15. UV-induced damage in dermoid variants

16. Repeated minor trauma (bruxism, chewing hard foods)

17. Idiopathic proliferation of dermal elements

18. Post-crush injury (car door, sports)

19. Embryonic ectodermal rest misplacement

20. Postoperative sequelae (e.g., cosmetic surgery) MedscapeJKSR.

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Symptoms

Patients with mastication muscle cysts may report:

1. Localized facial swelling

2. Gradual onset of a firm lump

3. Mild to moderate pain on chewing

4. Restricted mouth opening (trismus)

5. Facial asymmetry

6. Tenderness on palpation

7. Audible clicking near TMJ (if joint involved)

8. Numbness or tingling (if nerve compression)

9. Redness of overlying skin (if inflamed)

10. Fluctuant mass on examination

11. Dysphagia (if extending medially)

12. Altered bite alignment

13. Bruising (if recent trauma)

14. Visible central punctum (epidermoid)

15. Fistula formation (rare)

16. Drainage of keratinous material

17. Serous or purulent discharge

18. Fever (when secondarily infected)

19. Headache or earache

20. Progressive growth over weeks to months PMCPMC.

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Diagnostic Tests

Accurate diagnosis typically involves multimodal evaluation:

1. Clinical examination and history

2. Ultrasound imaging (cystic vs. solid)

3. Doppler ultrasound (vascular flow)

4. CT scan (bony involvement)

5. MRI (soft tissue delineation)

6. Fine-needle aspiration cytology (FNAC)

7. Core needle biopsy

8. Histopathological examination

9. Serologic tests for parasites (ELISA)

10. Stool ova and parasite exam (cysticercosis)

11. Hydatid serology (Echinococcus)

12. Contrast arthrography (TMJ cysts)

13. Sialography (salivary duct cysts)

14. PET scan (rule out neoplasm)

15. Blood tests (CBC, inflammatory markers)

16. Bacterial culture (if infected)

17. Fistulography (if sinus tract)

18. Ultrasound-guided aspiration

19. Electromyography (nerve involvement)

20. Intraoral endoscopy (deep lesions) SpringerOpenRSNA Publications.

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Non-Pharmacological Treatments

Conservative and minimally invasive approaches can relieve symptoms and reduce cyst size:

1. Clinical observation for small, asymptomatic cysts

2. Warm compresses to promote drainage

3. Cold packs for acute swelling

4. Ultrasound therapy to soften contents

5. Manual lymphatic drainage

6. Jaw stretching and physiotherapy

7. Transcutaneous electrical nerve stimulation (TENS)

8. Acupuncture for pain relief

9. Low-level laser therapy (LLLT)

10. Cryotherapy for superficial lesions

11. Fine-needle aspiration

12. Ultrasound-guided catheter drainage

13. Endoscopic-assisted drainage

14. Suture-guided marsupialization

15. Manual expression under local anesthesia

16. Myofascial release massage

17. Dietary modifications (soft diet)

18. Avoidance of hard or sticky foods

19. Behavior modification (avoid bruxism)

20. Dental splints to relieve stress

21. Orthotic appliances for TMJ

22. Hyperbaric oxygen therapy

23. Postural training and ergonomic advice

24. Speech therapy (if swallowing affected)

25. Behavioral therapy for parafunctional habits

26. Heat-packs combined with gentle massage

27. Ultrasound-guided ethanol instillation (for lymphatic)

28. Endoscopic marsupialization

29. Guided radiofrequency ablation

30. Image-guided cryoablation ScienceDirectRadiopaedia.

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Drugs

Pharmacotherapy targets pain, inflammation, infection, or parasitic causes:

1. Ibuprofen (NSAID for pain/inflammation)

2. Acetaminophen (analgesic)

3. Naproxen (NSAID)

4. Diclofenac (NSAID)

5. Prednisone (systemic corticosteroid)

6. Amoxicillin–clavulanate (broad-spectrum antibiotic)

7. Clindamycin (anaerobic coverage)

8. Cephalexin (first-generation cephalosporin)

9. Metronidazole (anaerobic bacteria)

10. Albendazole (anti-helminthic for cysticercosis)

11. Praziquantel (treatment for tapeworm cysts)

12. Ivermectin (parasiticides)

13. Sirolimus (mTOR inhibitor for lymphatic malformations)

14. OK-432 (Picibanil) (sclerosing agent)

15. Bleomycin (sclerotherapy adjunct)

16. Doxycycline (sclerosing and antibiotic)

17. Prednisolone mouthwash (topical inflammation)

18. Triptans (if headache associated)

19. Muscle relaxants (e.g., cyclobenzaprine)

20. Botulinum toxin (for masseter hypertrophy) MedscapeNCBI.

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Surgeries

Surgical management is reserved for persistent, large, or complicated cysts:

1. Enucleation (complete excision)

2. Marsupialization (creating a permanent opening)

3. Peripheral ostectomy (removing bone margins)

4. Endoscopic-assisted cyst removal

5. Laser excision (CO₂ laser)

6. Cryosurgical excision

7. Open surgical drainage with drain placement

8. CT-guided percutaneous drainage

9. Flap reconstruction (if significant tissue loss)

10. Bone grafting (post-cystectomy defect repair) RadiopaediaScienceDirect.

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Prevention Strategies

Preventive measures can lower the risk of cyst formation:

1. Maintain excellent oral hygiene

2. Attend regular dental check-ups

3. Avoid facial trauma (use protective gear)

4. Cook pork thoroughly (prevent cysticercosis)

5. Practice deworming protocols in endemic areas

6. Seek early treatment of odontogenic infections

7. Use proper technique in oral surgery and injections

8. Manage bruxism with night guards

9. Limit UV exposure (dermoid prevention)

10. Educate patients on avoiding self-trauma to lesions MedlinePlusJKSR.

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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.

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Frequently Asked Questions

1. 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.

2. 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.

3. 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.

4. 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.

5. Are they painful?
   Many are painless but can become tender if they enlarge or become secondarily inflamed or infected PMC.

6. How are they diagnosed?
   Diagnosis is based on clinical exam, imaging (ultrasound, CT, MRI), and often fine-needle aspiration or biopsy RSNA Publications.

7. 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.

8. What are the risks of leaving a cyst untreated?
   Potential for growth, discomfort, trismus, secondary infection, or damage to surrounding structures Medscape.

9. Is surgery always necessary?
   Not always—many cysts can be managed conservatively or with minimally invasive drainage if small and uninfected ScienceDirect.

10. 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.

11. Can these cysts recur after excision?
    Recurrence is uncommon if the cyst is completely removed; incomplete excision raises the risk of recurrence Synapse.

12. Do they affect eating or speaking?
    Large cysts or those causing trismus can interfere with chewing or speech, which usually resolves after treatment PMC.

13. Are parasitic cysts in these muscles preventable?
    Yes—proper cooking of meat, good hygiene, and deworming in endemic areas can reduce risk MedlinePlus.

14. What specialists treat mastication muscle cysts?
    Oral and maxillofacial surgeons, ENT specialists, or head and neck radiologists typically manage these lesions SpringerOpen.

15. 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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The article is written by Team Rxharun and reviewed by the Rx Editorial Board Members

Last Updated: April 24, 2025.

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