Poland syndrome

Poland syndrome is a rare congenital malformation characterised by unilateral absence or hypoplasia of the sternocostal head of the pectoralis major muscle, often with ipsilateral breast, nipple, chest-wall and upper-limb anomalies波兰综合征是一种罕见的先天性畸形，表现为胸大肌胸肋头单侧缺如或发育不良，常伴同侧乳房、乳头、胸壁与上肢异常。

The defect is usually right-sided and sporadic, and it ranges from an isolated mild muscular asymmetry to a severe chest-wall and limb malformation该缺陷通常位于右侧且多为散发，范围从孤立的轻度肌肉不对称到严重的胸壁与肢体畸形不等。

Diagnosis is clinical and confirmed by imaging, while treatment is mainly reconstructive and is usually planned around puberty诊断以临床为主并经影像确认，治疗主要为重建手术，通常围绕青春期进行规划。

Terminology and classification

• Poland syndrome is also called Poland anomaly or Poland sequence because the pectoral, breast and limb defects are thought to arise from a single developmental disturbance波兰综合征又称波兰畸形或波兰序列，因为胸部、乳房与肢体缺陷被认为源自同一发育紊乱。^[1]
• The eponym honours Alfred Poland, who described the association of pectoral muscle absence and ipsilateral hand deformity in 1841该名称纪念阿尔弗雷德·波兰，他于1841年描述了胸肌缺如与同侧手部畸形的关联。^[1]
• ICD-10 codes the condition as Q79.8, other congenital malformations of the musculoskeletal system, and ICD-11 assigns the specific code LB73.10《国际疾病分类》第十版将其编码为 Q79.8，即肌肉骨骼系统其他先天性畸形，第十一版则赋予专门编码 LB73.10。^[2]
• Cross-references include OMIM 173800, Orphanet ORPHA:2911, MONDO:0008262, MeSH D011045 and Wikidata Q633859交叉参照包括 OMIM 173800、Orphanet ORPHA:2911、MONDO:0008262、MeSH D011045 与 Wikidata Q633859。^[2]
• The thorax-breast-nipple classification separates chest-wall, breast and nipple involvement and is used to plan reconstruction胸壁-乳房-乳头分类将胸壁、乳房与乳头受累分开评估，并用于规划重建手术。^[3]
• A three-tier clinical classification distinguishes type 1 isolated pectoral defect, type 2 pectoral defect with either upper-limb or rib anomaly, and type 3 combined upper-limb and rib anomalies三级临床分类区分1型孤立胸肌缺陷、2型胸肌缺陷合并上肢或肋骨异常，以及3型上肢与肋骨异常并存。^[3]

History

• Alfred Poland described the post-mortem findings of pectoral muscle absence with syndactyly in 1841 while working at Guy's Hospital in London阿尔弗雷德·波兰于1841年在伦敦盖伊医院工作时，描述了尸检发现的胸肌缺如合并并指畸形。^[1]
• The term Poland syndrome was popularised by Clarkson in 1962, and subsequent series established the variable involvement of the breast, ribs and upper limb波兰综合征这一术语由克拉克森于1962年推广，随后的病例系列确立了乳房、肋骨与上肢受累的变异性。^[1]
• In 2014 a de novo deletion of chromosome 11q12.3 was reported in monozygotic twins concordant for Poland syndrome, supporting a genetic contribution2014年一对同患波兰综合征的同卵双胞胎被发现携带染色体11q12.3新发缺失，支持遗传因素的作用。^[4]
• Consensus-based recommendations for diagnosis and medical management were published in 2020 by an international group of specialists2020年一个国际专家小组发表了基于共识的诊断与医疗管理推荐。^[2]
• In 2022 a de novo SFMBT1 variant was identified in a boy with Poland syndrome, and a PLXND1 mutation was reported in Poland-Möbius syndrome2022年一名波兰综合征男童被发现携带 SFMBT1 新发变异，另一项报告在波兰-莫比乌斯综合征中发现 PLXND1 突变。^[5]

Epidemiology

• Orphanet estimates a prevalence of 1–9 per 100,000 and an incidence of about 1 per 30,000 live births, although the incidence is probably underestimatedOrphanet 估计患病率为每十万分之1至9，发病率约为每3万活产1例，但实际发病率可能被低估。^[2]
• Males are affected about twice as often as females, and the right side is involved in the majority of casesbilateral involvement is rare and accounts for about 1 per cent 男性患病约为女性的两倍，多数病例累及右侧，双侧受累罕见，约占1%。^[2]
• Most cases are sporadic, but about 4 per cent are familial, and autosomal dominant, autosomal recessive and multifactorial patterns have all been described多数病例为散发，但约4%为家族性，常染色体显性、常染色体隐性及多因素模式均有描述。^[2]
• Upper-limb anomalies occur in about 56 per cent of patients, most often brachydactyly, syndactyly or hypoplasia of the middle phalanges约56%的患者存在上肢异常，最常见为短指、并指或中指骨发育不良。^[2]
• Dextrocardia occurs in about 10 per cent of cases and is associated with left-sided rib agenesis rather than with isolated pectoral defects约10%的病例出现右位心，且与左侧肋骨缺如相关，而非孤立性胸肌缺陷。^[6]
• Mild forms are more common than severe forms, and many adults with subtle asymmetry are never diagnosed, which biases clinic-based estimates轻型病例多于重型，许多仅有轻微不对称的成人从未被诊断，这使基于门诊的估计产生偏倚。^[7]
• The condition occurs worldwide without a clear ethnic predilection, and its reported incidence has ranged from 1 in 10,000 to 1 in 100,000 live births该病在全球范围内发生，无明显种族倾向，报告发病率从每1万活产1例到每10万活产1例不等。^[7]

Pathophysiology

• The leading hypothesis is a vascular disruption of the subclavian artery or its branches around the sixth week of gestation, which reduces perfusion to the developing pectoral muscle and limb bud主要假说认为妊娠第六周前后锁骨下动脉或其分支发生血管破坏，导致发育中的胸肌与肢芽灌注不足。^[1]
• The pectoralis major sternocostal head is consistently affected, the pectoralis minor is often absent, and the serratus anterior, latissimus dorsi or trapezius may be hypoplastic in severe forms胸大肌胸肋头恒定受累，胸小肌常缺如，严重型还可有前锯肌、背阔肌或斜方肌发育不良。^[2]
• Breast and nipple hypoplasia is thought to reflect the same regional vascular insult, and in females the nipple-areolar complex is often hypoplastic and displaced superolaterally乳房与乳头发育不良被认为反映同一区域血管损伤，女性乳头乳晕复合体常发育不良并向上外侧移位。^[2]
• Rib aplasia or hypoplasia can permit lung herniation, and left-sided rib agenesis reduces left hemithorax volume, which may explain the association with dextrocardia肋骨缺如或发育不良可导致肺疝，左侧肋骨缺如降低左半胸容积，这可能解释其与右位心的关联。^[6]
• Genetic heterogeneity is evident: an 11q12.3 deletion, SFMBT1 variants and PLXND1 variants in Poland-Möbius syndrome implicate developmental and angiogenic pathways遗传异质性明显：11q12.3 缺失、SFMBT1 变异以及波兰-莫比乌斯综合征中的 PLXND1 变异均涉及发育与血管生成通路。^[5]
• No single gene explains most cases, and the phenotype probably results from the interaction of vascular, genetic and environmental factors during a narrow developmental window没有单一基因能解释多数病例，表型可能源于血管、遗传与环境因素在狭窄发育窗口内的相互作用。^[8]

Clinical features

• The hallmark is unilateral chest asymmetry with absence of the anterior axillary fold, and asking the patient to press the palms together accentuates the pectoral defect标志性表现为单侧胸部不对称及腋前褶消失，让患者双掌相压可突出胸肌缺陷。^[2]
• In females, breast volume, nipple position and areolar size are usually reduced on the affected side, and pectoral and axillary hair may be sparse or absent女性患侧乳房体积、乳头位置与乳晕大小通常减小，胸毛与腋毛可稀疏或缺失。^[2]
• Chest-wall involvement may include rib hypoplasia or aplasia, pectus excavatum, contralateral pectus carinatum and lung herniation during coughing胸壁受累可包括肋骨发育不良或缺如、漏斗胸、对侧鸡胸以及咳嗽时肺疝。^[2]
• Upper-limb findings include brachydactyly, syndactyly, phalangeal hypoplasia and, rarely, hypoplasia of the hand or forearm上肢表现包括短指、并指、指骨发育不良，罕见手或前臂发育不良。^[3]
• Dextrocardia should be excluded in left-sided disease with rib agenesis, and cardiac assessment is warranted before thoracic reconstruction左侧病变合并肋骨缺如时应排除右位心，胸壁重建前需进行心脏评估。^[6]
• Most patients have no major muscle weakness, but extensive defects can reduce shoulder girdle strength, exercise tolerance and tolerance of chest-wall pressure多数患者无明显肌力下降，但广泛缺陷可降低肩带力量、运动耐量与对胸壁压迫的耐受。^[2]
• The visible asymmetry and breast differences can cause body-image distress, social avoidance and reduced quality of life, particularly during adolescence可见的不对称与乳房差异可引起体像困扰、社交回避与生活质量下降，尤其在青春期。^[7]

Diagnosis

• Diagnosis is primarily clinical, based on inspection, palpation, measurement of nipple position and the palm-pressing manoeuvre诊断主要依靠临床，包括视诊、触诊、乳头位置测量与双掌相压试验。^[2]
• Ultrasound confirms absence or hypoplasia of the pectoral muscles and breast tissue and can detect rib cartilage anomalies in experienced hands超声可确认胸肌与乳腺组织缺如或发育不良，在熟练操作者中还能发现肋软骨异常。^[2]
• Chest radiography documents rib agenesis, lung herniation and cardiac position, while computed tomography or magnetic resonance imaging defines the extent of muscle and chest-wall defects before surgery胸部X线可记录肋骨缺如、肺疝与心脏位置，计算机断层或磁共振成像则在术前明确肌肉与胸壁缺陷范围。^[2]
• The thorax-breast-nipple classification and the three-tier scheme published in 2018 standardise description, support surgical planning and allow outcome comparison between series2018年发表的胸壁-乳房-乳头分类与三级分类方案可标准化描述、支持手术规划，并使不同病例系列的结局可以比较。^[3]
• Genetic testing, such as chromosomal microarray or a targeted gene panel, is reserved for familial cases, syndromic features or associated developmental delay染色体微阵列或靶向基因组合等遗传检测，保留用于家族性病例、综合征表现或合并发育迟缓者。^[5]
• The differential diagnosis includes Moebius syndrome, Klippel-Feil syndrome, Pierre Robin sequence, Sprengel deformity, Carey-Fineman-Ziter syndrome, isolated chest-wall anomalies and thoracic lipoatrophy鉴别诊断包括莫比乌斯综合征、克利佩尔-费尔综合征、皮埃尔-罗宾序列、斯普伦格尔畸形、凯里-菲尼曼-齐特综合征、孤立性胸壁异常与胸部脂肪萎缩。^[2]
• Antenatal diagnosis is rare, but a fetal hand anomaly or chest asymmetry may prompt targeted ultrasound and postnatal evaluation产前诊断罕见，但胎儿手部异常或胸部不对称可提示针对性超声与出生后评估。^[2]

Management

• Management is multidisciplinary, involving plastic and reconstructive surgery, thoracic surgery, paediatrics, orthopaedics, physiotherapy and psychological support管理需要多学科协作，涉及整形重建外科、胸外科、儿科、骨科、物理治疗与心理支持。^[2]
• Surgery is mainly cosmetic, but rib-cage reconstruction may be needed when a severe defect causes lung herniation, respiratory compromise or cardiac compression手术主要出于美容目的，但当严重缺陷导致肺疝、呼吸受限或心脏受压时，可能需要重建胸廓。^[2]
• Patients should be evaluated at the beginning of puberty and before complete growth, and a combined paediatric-thoracic and plastic-surgery plan is preferred患者应在青春期开始、生长完成前接受评估，并优先采用儿科胸外科与整形外科联合方案。^[2]
• Custom-made pectoral or breast implants, tissue expanders and autologous fat grafting can restore chest contour, and fat grafting may be used before or after implantation定制胸肌或乳房假体、组织扩张器与自体脂肪移植可恢复胸部轮廓，脂肪移植可在假体植入前或后使用。^[2]
• Extensive rib agenesis may require non-absorbable mesh, metallic plates or custom prostheses, and lung hernia repair is performed when the defect is symptomatic广泛肋骨缺如可能需要不可吸收补片、金属板或定制假体，症状性肺疝则需修补。^[2]
• Muscle transposition, such as latissimus dorsi transfer, is reserved for selected cases and should not be performed in children背阔肌转移等肌肉移位术仅用于特定病例，且不应在儿童中实施。^[2]
• Syndactyly release is generally performed between 12 and 24 months of age, and absent phalanges may be treated with non-microvascular or microvascular toe-to-hand transfer并指松解通常在12至24月龄之间进行，指骨缺如可采用非显微血管或显微血管足趾移植。^[2]
• Contralateral breast surgery may improve symmetry, and physiotherapy plus psychological support should accompany surgical reconstruction throughout adolescence对侧乳房手术可改善对称性，物理治疗与心理支持应贯穿青春期的手术重建过程。^[2]

Research and controversies

• The genetic architecture remains unresolved, because SFMBT1, 11q12.3 and PLXND1 explain only a small minority of cases and most patients have no identified variant遗传结构仍未明确，因为 SFMBT1、11q12.3 与 PLXND1 仅能解释少数病例，多数患者未发现致病变异。^[5]
• The vascular-disruption hypothesis, summarised in a 2009 review, is widely accepted but difficult to test directly, and no animal model fully reproduces the pectoral, breast and limb phenotype2009年的一篇综述总结了血管破坏假说，该假说虽被广泛接受，却难以直接验证，也没有动物模型能完整复制胸肌、乳房与肢体表型。^[1]
• Long-term comparative studies are needed to define the durability of custom implants, fat grafting and rib reconstruction and to compare patient-reported outcomes across techniques需要长期比较研究来确定定制假体、脂肪移植与肋骨重建的持久性，并比较不同技术的患者报告结局。^[3]
• International registries and standardised outcome sets would improve evidence for timing of surgery, psychological support and management of mild forms that are currently left untreated国际登记库与标准化结局指标集将改善手术时机、心理支持以及目前未治疗的轻型病例管理方面的证据。^[2]

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