Poland Syndrome: An Overview

What Is Poland Syndrome?

Poland Syndrome is a rare congenital condition characterised by the unilateral absence or underdevelopment of the pectoralis major muscle — typically the sternal head — in combination with ipsilateral hand and upper limb abnormalities ranging from brachydactyly (shortened fingers) to complete absence of fingers (ectrodactyly) or syndactyly (fused digits). Additional features may include absence of the pectoralis minor, serratus anterior, and latissimus dorsi; rib abnormalities; and breast aplasia or hypoplasia in female patients. The condition occurs in approximately 1 in 20,000–30,000 live births, with a higher prevalence in males and a predominance of right-sided involvement.

The aetiology is thought to involve interruption of the subclavian artery blood supply during fetal development at approximately 46 days of gestation, producing a spectrum of ischaemic tissue disruption. The condition is typically sporadic, though rare familial cases have been reported.

Clinical Implications

The absent or hypoplastic pectoralis major produces characteristic chest wall asymmetry — often first noticed in childhood or adolescence as asymmetrical chest development, nipple elevation on the affected side, or asymmetry in the anterior axillary fold. The absence of the anterior axillary fold — the web of tissue normally formed by the pectoralis major inserting into the humerus — is a clinical sign visible on inspection and confirmed by inability to produce the fold on resisted adduction.

Musculoskeletal implications include altered scapular mechanics due to the absent or reduced muscular contribution to scapular stability and humeral depression. Compensatory hypertrophy of the contralateral pectoralis and ipsilateral deltoid, supraspinatus, and upper trapezius is common. Manual therapy assessment should map these compensatory patterns and address myofascial restrictions and trigger point activity within the hypertrophied compensators, rather than attempting to "balance" a structurally absent muscle. Surgical reconstruction options include latissimus dorsi transfer or implant-based chest wall reconstruction for cosmetic and functional indications.