Myositis ossificans mimicking metaplastic breast cancer on core needle biopsy

Myositis ossificans mimicking bone surface osteosarcoma: case report with literature review

Myositis ossificans, a benign tumor composed of spindle cells and osteoblasts, can clinically and radiologically mimic osteosarcoma. While recognition and accurate diagnosis of myositis ossificans can be a challenge, this is critical as it may allow a conservative surgical approach to maximize functional outcomes. Herein, we present a patient with surface myositis ossificans confirmed genetically by the presence of COL1A1::USP6 gene fusion, along with a literature review. Due to the enhanced visualization of the bone matrix, computed tomography (CT) imaging may be a superior imaging modality to magnetic resonance (MR) imaging. Staged biopsies with samples obtained from the periphery and center of the lesions may allow pathologists to discern the zonal distribution histologically. Furthermore, immunohistochemistry fluorescence in situ hybridization and molecular testing can aid in the distinction of myositis ossificans from mimics. Because of their resemblance to other bone tumors, these cases of myositis ossificans highlight the importance of a multidisciplinary approach integrating clinical, radiologic, and pathologic analysis and involving serial imaging, sampling, and judicious use of ancillary immunohistochemical and molecular testing.

Osório CAB, Bitencourt AGV, Makdissi FBA, do Nascimento AG. Myositis Ossificans of the Breast Mimicking Breast Cancer: A Case Report

Myositis ossificans (MO) is an uncommon tumor characterized by a rapidly growing mass following a history of local trauma. Few cases of MO affecting the breast have been reported, and some were misdiagnosed as primary osteosarcoma of the breast or metaplastic breast carcinoma. The following case report presents a patient with a growing breast lump whose core biopsy result was suspicious for breast cancer. MO was diagnosed after analysis of the mastectomy specimen. This case highlights the importance of MO as a differential diagnosis of a growing soft-tissue mass after trauma to avoid unnecessary overtreatment. Keywords: Myositis Ossificans, Osteosarcoma, Breast Cancer, Mastectomy, Heterotopic Ossification © RSNA, 2023.

Myositis ossificans of the breast - A rare case report with radiologic-pathologic correlation

Myositis ossificans is a pathologic process of ossification in soft tissues. The breast is an exceptionally rare location for myositis ossificans with less than 5 cases documented in the English literature. We present a case of a 66-year-old woman with myositis ossificans of the left breast and no known initiating trauma. The significance of the progression of clinical and radiological findings are discussed in detail. This case shows the importance of radiology for identifying unique pathology as well as close radiological follow up.

Are open surgery and total resection good choices for traumatic myositis ossificans in children?

BACKGROUND

Traumatic myositis ossificans is a self-limited, non-neoplastic, ectopic bone formation in the soft tissues caused by trauma. Conservative treatment is the mainstay of management. However, open surgery and complete resection should be considered in patients with limited joint function and constant pain. Herein, we retrospectively analyzed the outcome of open surgical resection in children with myositis ossificans (MO).

METHODS

The data of patients diagnosed with MO between February 2010 and May 2019 were retrospectively analyzed. The clinical data included medical history, physical examination, and laboratory, imaging, and pathological findings. All patients underwent an open surgery and total resection. Radiography findings and joint function were evaluated. Patients with developing complications, such as recurrence and assessing joint function, were followed up. In total, 20 patients (sex, 15 male and 5 female patients; age, 8.1 ± 2.5 years) were included.

RESULTS

MO was located around the elbow, wrist, proximal humerus, and thigh in 13, one, one, and five patients, respectively. All patients were followed up for > 12 months. Two patients had partial recurrence after surgery. One patient with forearm MO had poor elbow function (Broberg-Morrey score of 70). Nineteen patients had good functional outcomes according to the Broberg-Morrey and Cooney methods.

CONCLUSION

Open surgical resection is an effective method for children with MO. The recurrence rate was low when the surgery was performed after the acute stage (1.5 months from disease presentation).

Solitary Bone Cyst Like Areas in Myositis Ossificans: A Breast Mass in a Child

Myositis ossificans is an extraosseous, benign tumor-like condition characterized by prominent heterotopic ossification. Cystic degeneration in myositis ossificans is an uncommon entity. Case report: A 13-year-old girl presented with a large and painful breast lump. Physical examination revealed a mobile, hard mass, clinically resembling a fibroadenoma. The mass was excised and diagnosed as myositis ossificans with central bone cyst like changes. Conclusion: Our case represents the first myositis ossificans case with central bone cyst like changes in a child.

The diagnostic value of ultrasound-guided percutaneous core needle biopsy of musculoskeletal soft tissue lesions

Introduction

Percutaneous ultrasound-guided core needle biopsy is a well-established method in the diagnosis of musculoskeletal tumors. It is unclear which factors contribute the most to a successful biopsy. The aim of the study was to determine the value of ultrasound-guided core needle biopsy of solid lesions in the musculoskeletal system using a 16-gauge needle.

Material and methods

A retrospective analysis performed at a regional sarcoma center over one year included patients referred for ultrasound-guided biopsy of musculoskeletal soft tissue lesions. At least 6 months’ clinical and radiological follow-up, results from repeat or excisional biopsy, or interventional treatment, served as outcome reference. The biopsy procedure and yield were analyzed. The biopsy was classified as ‘diagnostic’ when a definitive diagnosis could be made on the first biopsy, and ‘accurate’ when only the malignant or benign nature of the tumor could be determined.

Results

From 102 referrals for biopsy of soft tissue lesions in 2019, a total of 73 biopsies of solid lesions with a 16-gauge cutting needle were included (73 patients). There were 34 males and 39 females, with a mean age of 57.7 years. The overall proportion of diagnostic biopsies was 84%, for malignant lesions 88% and benign lesions 81%. The tumor could be classified as malignant or benign in 12 patients (16%) (accurate biopsy). It was possible to discriminate between malignant and benign lesions in each case. The majority of biopsied lesions were benign 64% (n = 47).

Conclusion

The diagnostic value of ultrasound-guided percutaneous core needle biopsy of musculoskeletal soft tissue lesions performed with 16-gauge needle is good, with a high rate of diagnostic biopsies, both for benign and malignant lesions.