Leiomyosarcoma With Dedifferentiation Mimicking a Benign Neoplasm

Area of Science:

• Oncology
• Dermatopathology
• Soft Tissue Sarcomas

Background:

• Superficial leiomyosarcoma is a rare soft tissue sarcoma, typically affecting adults over 50 with firm, painful nodules.
• Cutaneous dedifferentiated leiomyosarcoma is exceptionally rare, with only two prior reported cases, both presenting differently.

Purpose of the Study:

• To report a unique case of superficial leiomyosarcoma with dedifferentiation in an unusual demographic and location.
• To highlight the diagnostic challenges posed by atypical presentations of soft tissue sarcomas.

Main Methods:

• Histopathologic evaluation of an excisional biopsy specimen.
• Immunohistochemical staining for smooth muscle actin and desmin.
• Clinical correlation and review of existing literature.

Main Results:

• An intermediate-grade leiomyosarcoma with focal dedifferentiation was identified, showing abrupt transition to a high-grade undifferentiated sarcoma.
• Immunohistochemistry revealed loss of smooth muscle actin and desmin in the dedifferentiated area.
• The patient achieved clear margins after wide local excision with no evidence of metastasis.

Conclusions:

• This case underscores the importance of considering malignancy in persistent subcutaneous nodules, even with atypical presentations.
• Early recognition and surgical intervention are vital due to the aggressive nature and metastatic potential of dedifferentiated leiomyosarcoma.
• This report contributes to the limited understanding of cutaneous dedifferentiated leiomyosarcoma, particularly its varied clinical manifestations.