Unilateral Pectoralis Agenesis on MRI: Poland Syndrome

Complete left pectoralis major and minor absence on MRI, with normal pectoral nerves on MR neurography, points to congenital agenesis—a classic Poland syndrome hallmark often accompanied by syndactyly and other anomalies.

• Unilateral absence of pectoralis major and minor with normal medial and lateral pectoral nerves favors congenital agenesis over chronic post-traumatic denervation.
• MR neurography can exclude a neurogenic cause when the brachial plexus branches appear normal.
• Poland syndrome classically includes unilateral pectoral agenesis, often with syndactyly and other anomalies.

Automated summary

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