When presented with a possible case of masticatory myositis, it is important to remember there are two potential presentation types: acute and chronic forms.

Clinical signs associated with the acute form include:

• Fever
• Regional lymphadenopathy
• Muscles of mastication swelling which are painful on palpation
• Exophthalmos
• Resists or unable to open the mouth

Clinical signs associated with the chronic form include:

• Atrophy of the masticatory muscles
• Muscle swelling/atrophy can be asymmetric
• Enophthalmos
• Inability to open mouth fully