A case of bilateral extensor digitorum brevis manus.

Area of Science:

• Anatomy
• Musculoskeletal System
• Surgical Pathology

Background:

• The Extensor Digitorum Brevis Manus (EDBM) is an aberrant muscle occasionally found in the dorsal wrist.
• Ganglion cysts are common dorsal wrist masses, often diagnosed via ultrasound.

Observation:

• A 72-year-old man presented with a symptomatic dorsal wrist mass causing pain during daily activities.
• A similar, asymptomatic mass was present on his dominant wrist.
• Ultrasound diagnosed the symptomatic mass as a synovial ganglion; surgical excision revealed an aberrant EDBM.

Findings:

• Histological evaluation confirmed the presence of viable aberrant muscular tissue, identified as Extensor Digitorum Brevis Manus.
• A contralateral, asymptomatic EDBM was detected via MRI three months later, consistent with literature reporting occasional bilaterality.

Implications:

• This case highlights the importance of considering aberrant musculature in the differential diagnosis of dorsal wrist masses.
• Awareness of potential bilaterality is crucial for comprehensive patient assessment, even in asymptomatic contralateral limbs.
• Further investigation may be warranted for asymptomatic dorsal wrist masses to rule out underlying aberrant musculature.