Low-Grade Myofibroblastic Sarcoma on Back with Repeated Localized Recurrence and Regional Metastasis

Area of Science:

• Oncology
• Surgical Pathology

Background:

• Low-grade myofibroblastic sarcoma (LGMS) is a rare spindle cell neoplasm characterized by an indolent clinical course.
• Accurate diagnosis of LGMS can be challenging due to its rarity and low-grade histologic features, often leading to misdiagnosis.

Observation:

• A 63-year-old female presented with a left back mass initially diagnosed as nodular fasciitis.
• The mass recurred 18 months later, exhibiting pain and growth, prompting re-evaluation.
• Histopathology revealed atypical spindle cells with whorling patterns, suggestive of low-grade sarcoma, later confirmed as LGMS.

Findings:

• Despite three wide excisions achieving clear margins and adjuvant radiotherapy, the LGMS case demonstrated repeated local recurrence.
• The tumor subsequently metastasized to the lungs, a rare occurrence for LGMS, particularly in this location.
• This case underscores the potential for aggressive behavior in LGMS, contrary to its typical indolent nature.

Implications:

• Accurate and timely diagnosis of LGMS is crucial, requiring high suspicion even with initial benign-appearing histology.
• The potential for aggressive local recurrence and distant metastasis necessitates careful long-term surveillance.
• This case expands the understanding of LGMS presentation and behavior, particularly in unusual locations like the back.