Pseudomalignant myositis ossificans involving multiple masticatory muscles: Imaging evaluation

Non-traumatic myositis ossificans circumscripta in the anterior abdominal wall of a seven-year-old Ugandan child: A case report

Myositis ossificans circumscripta (MOC) is a benign and self-limiting heterotopic ossification in the subcutaneous fat, tendons, muscles, and nerves. It is commonly due to trauma and is frequently encountered in the arm, shoulder, thigh, and hand which are prone to trauma. Non-traumatic MOC arising from the abdominal muscles is extremely rare. We report a case of 7-year-old male child with a three-year history of progressive painless abdominal swelling in the left hypochondria region with no history of associated trauma. CT scan of the abdomen showed a well-defined hyperdense mass in the left external oblique muscle. Histological diagnosis confirmed myositis ossificans of the external oblique muscle. The mass was removed surgically with no immediate or late complications.

Imaging review of normal anatomy and pathological conditions involving the popliteus

Popliteus is an integral component of the posterolateral corner of the knee. We review the anatomy and various pathologies affecting the popliteus.

Traumatic myositis ossificans: multifocal lesions suggesting malignancy on FDG-PET/CT-a case report

Myositis ossificans (MO) is a benign soft-tissue lesion characterized by the heterotopic formation of the bone in skeletal muscles, usually due to trauma. MO is occasionally difficult to diagnose because of its clinical and radiological similarities with malignancy. We report a case of traumatic MO (TMO) in the masseter and brachial muscles of a 37-year-old man who presented with painless swelling in the left cheek and severe trismus. Due to the absence of a traumatic history at the first consultation and identification of a tumorous lesion in the left masseter muscle by magnetic resonance imaging (MRI), the lesion was suspected to be a malignant tumor. Subsequently, 18F-fluorodeoxyglucose positron-emission tomography/computed tomography (FDG-PET/CT) showed multiple regions of high FDG uptake across the whole body, suggestive of multiple metastases or other systemic diseases. However, intramuscular calcifications were also observed in the left masseter and brachial muscles, overlapping the areas with high FDG uptake. Moreover, multiple fractures were seen in the rib and lumbar spine, also overlapping the areas with high FDG uptake. Based on these imaging findings, along with a history of jet-ski trauma, TMO was suspected. The left cheek mass was surgically excised and histologically diagnosed as TMO. In this case report, FDG-PET/CT could detect multiple TMOs across the whole body. To the best of our knowledge, cases of multiple TMOs located far apart in different muscles are rare, and this may be the first report.

Myositis Ossificans Traumatica of the Temporal Muscle: a Case Report and Literature Review Emphasizing Radiographic Features on Computed Tomography and Magnetic Resonance Imaging

Objectives

Heterotopic bone formation within a muscle is designated as ‘myositis ossificans’, and it is associated with multiple aetiologies, such as trauma, genetic predisposition, post-infection, or undetermined causes. When the disease develops as a result of a trauma, the myositis ossificans is classified as ‘myositis ossificans traumatica’. In this case report, a case of myositis ossificans traumatica is described, emphasizing its imaging features. Additionally, a literature review of the imaging features of myositis ossificans is discussed.

Material and Methods

A 60-year old male patient presented with restricted mouth opening and pain during mastication. Multislice computed tomography and magnetic resonance imaging examinations were conducted. Case reports in the literature of myositis ossificans were searched databases from August 1984 until April 2019 using the keyword ‘masticatory muscles’ combined with ‘myositis’; ‘inflammatory myositis’; infectious myositis’; ‘inflammatory muscle diseases’; ‘focal myositis’ and ‘proliferative myositis’. Data was summarised and evaluated according to a critical appraisal checklist for case reports.

Results

Multislice computed tomography demonstrated an ectopic hyperdense area arising from the coronoid bone and within the temporal muscle. Magnetic resonance imaging demonstrated the same area with a hypointense signal. In the literature review, 53 myositis ossificans cases were identified, and 12 cases affecting the temporal muscle were found.

Conclusions

The main imaging feature of myositis ossificans is the presence of a radiopaque, hyperdense or hypointense mass in the affected muscle, which is seen on multislice computed tomography and magnetic resonance imaging, respectively. The final diagnosis is through histopathological examination, although imaging can suggest the most likely diagnosis.

Peering beneath the surface: juxtacortical tumors of bone (part II)

Juxtacortical or surface tumors of bone are neoplasms arising from or just outside the cortex, and are composed of different histologic types. Although the imaging appearances of these lesions have similarities to their intramedullary counterparts, their location alters their radiographic and MR characteristics, creating difficulties in diagnosis. Meanwhile, several non-neoplastic lesions, such as stress reaction/stress fracture and indolent infectious processes, compound the differential diagnosis. Neoplastic juxtacortical lesions of bone have been classified into five categories: cartilaginous, fibrous, lipomatous, osseous, and metastatic tumors. Our goal in part two of this review is to illustrate the characteristic radiographic, CT and MR imaging features of various juxtacortical neoplasms, including pathognomonic imaging findings that can aid in diagnosis, and to develop an appropriate differential diagnosis for surface lesions based on imaging characteristics, lesion location and patient age.

Myositis Ossificans of the Hip Due to Pyogenic Arthritis Caused by Campylobacter fetus Subspecies fetus

A 61-year-old woman was admitted with severe hip pain causing immobility and high serum levels of inflammatory markers. The patient had a medical history of diabetes. She had been scheduled to undergo right hip replacement surgery for the treatment of osteoarthritis associated with gradually progressive pain. On admission, an enhanced abdominal computed tomography scan showed an abnormal increase in synovial fluid surrounding the right ilium, with piriformis muscle calcification. Subsequent blood and specimen cultures identified Campylobacter fetus subspecies fetus. This is a rare report of a case of myositis ossificans followed by C. fetus pyogenic arthritis of the hip.

A Rare Metastatic Myositis Ossificans of Obturator Muscle Secondary to Urothelial Carcinoma

The most frequent metastatic sites of the urothelial bladder cancers (UBCs) are bones, lungs, lymph nodes, liver, pleura, and brain. In the literature, skeletal muscle metastases from UBC have been rarely reported. We report a case of a 65-year-old male with metastatic myositis ossificans to obturator muscle 14 months after radical cystectomy performed for a muscle invasive transitional cell carcinoma. An abdomen computed tomography scan showed a lesion of about 8 cm in diameter in the left obturator muscle with myositis ossificans aspect. Ultrasound guided biopsy specimen of the left obturator muscle revealed poorly differentiated metastatic urothelial carcinoma with malignant myositis ossificans aspects. The patient refused additional surgery and received systemic chemotherapy and radiotherapy at the site of the lesion. The patient more than 6 months after treatment has a good performance status with a partial reduction of the mass and negative imaging for metastases in the follow-up.