Table 1.

Differential diagnosis of isolated unilateral temporalis muscle swelling

I. Reactive masticatory muscle hypertrophy (MMH) (progressive fiber type 1 predominance) [3]

II. Non-reactive MMH (modified after Harriman [3])

A. Genetic (or possibly genetic) MMH (fiber type 2 hypertrophy) [3]

B. Congenital MMH [3]

C. Masticatory muscle myopathy (hypertrophic branchial myopathy) [3, 7, 14, 15]

D. Vascular malformation—intramuscular cavernous hemangioma [3, 8]

E. Inflammatory processes

Focal myositis [1]

Eosinophilic fasciitis [9]

Ascending (necrotizing) fasciitis secondary to odontogenic infections [10]

Idiopathic inflammatory myopathy [3]

Infective causes—submasseteric abscess (severe pain and trismus) [3]

F. Neoplastic processes

Benign

Lipoma [4, 5]

Malignant

Intramuscular lymphoma [2]

Leukemic infiltration/granulocytic sarcoma [11]

Primary soft tissue sarcomas (liposarcoma and rhabdomyosarcoma) [4, 5]

Metastatic tumors (carcinoma [12], melanoma [13], and sarcoma)