eRadiograph Volume 7: Imaging of Oral Cavity | Page 196

PSEUDOMASS
These are lesions which may simulate a mass lesions on physical examination or
imaging.
Three psuedomass may occur in the masticator space.
1. Asymetric accessory parotid gland, this may be present in 21% of the
population. It appears as tissue lying along the surface of the masseter muscle which
resembles parotid tissue in signal intensity.
2. Bruxism - masseteric hypertrophy usually occurring due to grinding of teeth. This
may be unilateral or bilateral. Appearing as homogenous enlargement of the muscle
with no alteration in signal intensity of muscle.

INFECTION
The most common pathologic process to affect the masseteric space is infection. The
most common site of origin of infection is the teeth especially the third molar. Infection
arising in this location usually tracks medially, as the lingual cortex of the mandible is
thinner than the buccal cortex. Infection which tracks medially involves the medial
pterygoid muscle. Infection tracking laterally involves the masseteric muscle.
Involvement of the muscles of the mastication causes trismus. Other routes of spread
of odotogenic infection are posteriorly to the retromolar trigone, across the
parapharyngeal space to the lateral wall of the oropharynx. Extension to the
oropharynx may result in airway compromise. Other infectious sites that may involve
the masticator space may be from outside the masticator space which extend to the
masticator space such as parotitis extending from parotid space to masticator space
and from lateral pharyngeal wall such as a peritonsillar abscess to the masticator space
via the parapharyngeal fat pad. Otitis externa may also extend anteriorly to involve
masticator space. Osteomyelitis of the mandible may occur. On imaging the CT
findings of osteomyelitis are of cortical erosion, periosteal reaction, sequestration and
associated abscess, soft tissue and cellulitis.
NEOPLASM
Neoplasms may arise in tissues normally present in the masticator space. These include
Nerve sheath tumors, Lymphoma, soft tissue sarcomas and tumors of the mandible.
Nerve sheath tumors are usually benign and maybe schwannoma or

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Masticator Space

3. V3 branch denervation - In the acute setting there is enlargement of the muscles
with enhancement, Which may mimic an inflammatory or infective process. The key
to the diagnosis is a mass lesion at the skull base involving the foramen of ovale or
enhancement of the V3 nerve at the foramen oval indicating neural origin for the
muscle denervation.