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Multiple facial prominences of benign origin

      1. Case presentation

      An 18-year-old girl sought medical advice for an asymptomatic prominence of the right malar region evolving for two years because of cosmetic concern. Her medical history was relevant for Salmonella infection during a trip in Africa. The patient did not consume alcohol or use illicit drugs. She reported no history of trauma, fever, blurred vision or headache. On examination she was healthy. A prominence of the left lateral jaw was observed with normal overlying skin, limited mobility, and not painful to palpation. (Fig. 1A). Enlargement of the left jaw and right temporalis region with no signs of inflammation was also found. Clinical examination was otherwise unremarkable. Routine blood examination including blood cell count and creatine phosphokinase level was normal, search for antinuclear antibody and myositis-specific autoantibodies was negative. Head Magnetic Resonance Imaging (MRI) revealed a homogenous hypertrophy of left and right masseters and right temporalis with no signs of myositis, and no intracranial or bone lesions were detected (Figs. 1B and C).
      Fig 1
      Fig. 1A: Asymmetric enlargement of right temporalis region and left jaw. B: Right temporalis muscle hypertrophy on a coronal MRI T1 image T1. C: left master muscle hypertrophy on a coronal MRI T2 image.

      1.1 What is the diagnosis?

      Asymmetric reactive masticatory muscle hypertrophy due to bruxism.

      2. Discussion

      Reactive masticatory muscle hypertrophy is a rare condition involving isolated or combined hypertrophy of all groups of masticatory muscles [
      • Da Silva K.
      • Mandel L.
      Bilateral temporalis muscle hypertrophy: a case report.
      ]. The etiology of masticatory muscle hypertrophy remains unclear. However, a parafunctional jaw movement is commonly admitted [
      • Katsetos C.D.
      • et al.
      Painful unilateral temporalis muscle enlargement: reactive masticatory muscle hypertrophy.
      ]. Indeed potential causes include local factors such as dental malocclusion, prognathism, temporomandibular joint disease and bruxism, but psychogenic factors may also play a role [
      • Katsetos C.D.
      • et al.
      Painful unilateral temporalis muscle enlargement: reactive masticatory muscle hypertrophy.
      ]. Diagnosis usually relies on the medical history, clinical examination, and non-invasive tests. However muscle biopsy can be useful in order to rule out non-reactive conditions such as myositis, trauma, neoplasm, lipomatosis and auto-immune disease [
      • Katsetos C.D.
      • et al.
      Painful unilateral temporalis muscle enlargement: reactive masticatory muscle hypertrophy.
      ]. Treatment of reactive masticatory muscle hypertrophy consists mainly of botulinum toxin injection in case of bruxism or surgical intervention for local factors [
      • Ranasinghe J.C.
      • Wickramasinghe C.
      • Rodrigo G.
      Isolated unilateral temporalis muscle hypertrophy in a child: a case report with literature review.
      ]. Our patient reported bruxism but declined any treatment.

      Declaration of Competing Interest

      All authors declare that there is no conflict of interest.

      References

        • Da Silva K.
        • Mandel L.
        Bilateral temporalis muscle hypertrophy: a case report.
        Oral Surg Oral Med Oral Pathol Oral Radiol Endodontology. 2006; 102: e1-e3
        • Katsetos C.D.
        • et al.
        Painful unilateral temporalis muscle enlargement: reactive masticatory muscle hypertrophy.
        Head Neck Pathol. 2014; 8: 187-193
        • Ranasinghe J.C.
        • Wickramasinghe C.
        • Rodrigo G.
        Isolated unilateral temporalis muscle hypertrophy in a child: a case report with literature review.
        BMC Pediatr. 2018; 18: 71