TITLE:
Nontraumatic Myositis Ossificans in a Muscle of Mastication
AUTHORS:
Tadahiko Utsunomiya, Masaaki Suemitsu, Miyuki Morikawa, Masanobu Matsuno, Hirotsugu Yamamoto, Hitomi Sakata, Kazuhiro Hasegawa, Masahiro Higuchi, Kayo Kuyama
KEYWORDS:
Myositis Ossificans, Muscle of Mastication, Heterotopic Ossification, Histopathology
JOURNAL NAME:
Open Journal of Stomatology,
Vol.6 No.5,
May
11,
2016
ABSTRACT: Myositis ossificans (MO) is an extraskeletal tumor-like lesion with bone formation, and is relatively rare in the head and neck region. We report herein a clinicopathological analysis of MO associated with a muscle of mastication. The patient was a 70-year-old Japanese woman who presented with a tumorous mass in the right parotid area and no history of trauma. The surgically excised tumorous lesion consisted of proliferating fibroblastic cells with no atypia in the central portion, and a formation of trabecular osteoid and/or bony tissue in the peripheral portion as the so-called “zonal phenomenon”. The final histological diagnosis was MO, and the lesion was located in the posterior belly of the digastric muscle on computer tomography. A review of the literature showed that many cases of MO predominantly affected the medial pterygoid and masseter muscle and showed a history of previous trauma. The present case represents a rare case of nontraumatic MO in the uncommon location of the posterior belly of the digastric muscle.