Multiple Bone Involvement in Low-grade Myofibroblastic Sarcoma Demonstrated on ¹⁸F-FDG PET/CT

Area of Science:

• Oncology
• Radiology
• Pathology

Background:

• Metastatic bone disease is a common complication of various cancers.
• Distinguishing primary bone tumors from metastases can be challenging.
• Low-grade myofibroblastic sarcoma (LGMS) is a rare soft tissue tumor with a low potential for metastasis.

Purpose of the Study:

• To report an extremely rare case of LGMS with extensive bone involvement.
• To emphasize the importance of considering LGMS in the differential diagnosis of multiple bone metastases.
• To illustrate the imaging characteristics of bone involvement in LGMS.

Main Methods:

• A 68-year-old woman presented with low back pain.
• Diagnostic imaging included T2-weighted fat-saturated MRI and 18F-FDG PET/CT.
• Pathological diagnosis was confirmed via biopsy and surgical resection.

Main Results:

• T2-weighted fat-saturated imaging showed hyperintense lumbar lesions suggestive of metastases.
• 18F-FDG PET/CT revealed multiple osteolytic and osteoblastic lesions with varying degrees of 18F-FDG uptake.
• The patient was diagnosed with low-grade myofibroblastic sarcoma (LGMS) with widespread bone involvement.

Conclusions:

• Multiple bone involvement is an exceptionally rare presentation of LGMS.
• LGMS should be included in the differential diagnosis for patients with multiple bone lesions, particularly when a primary source is not readily identified.
• Multimodality imaging plays a crucial role in characterizing these lesions.