Poland syndrome

What it is, symptoms and effects

From: MedlinePlus Genetics, National Library of Medicine

Poland syndrome is a disorder in which affected individuals are born with missing or underdeveloped muscles on one side of the body, resulting in abnormalities that can affect the chest, shoulder, arm, and hand. The extent and severity of the abnormalities vary among affected individuals.

People with Poland syndrome are typically missing part of one of the major chest muscles, called the pectoralis major. In most affected individuals, the missing part is the large section of the muscle that normally runs from the upper arm to the breastbone (sternum). The abnormal pectoralis major muscle may cause the chest to appear concave. In some cases, additional muscles on the affected side of the torso, including muscles in the chest wall, side, and shoulder, may be missing or underdeveloped. There may also be rib cage abnormalities, such as shortened ribs, and the ribs may be noticeable due to less fat under the skin (subcutaneous fat). Breast and nipple abnormalities may also occur, and underarm (axillary) hair is sometimes sparse or abnormally placed. In most cases, the abnormalities in the chest area do not cause health problems or affect movement.

Many people with Poland syndrome have hand abnormalities on the affected side, commonly including an underdeveloped hand with abnormally short fingers (brachydactyly); small, underdeveloped (vestigial) fingers; and some fingers that are fused together (syndactyly). This combination of hand abnormalities is called symbrachydactyly. Some affected individuals have only one or two of these features, or have a mild hand abnormality that is hardly noticeable; more severe abnormalities can cause problems with use of the hand. The bones of the forearm (radius and ulna) are shortened in some people with Poland syndrome, but this shortening may also be difficult to detect unless measured.

Mild cases of Poland syndrome without hand involvement may not be evident until puberty, when the differences (asymmetry) between the two sides of the chest become more apparent. By contrast, severely affected individuals have abnormalities of the chest, hand, or both that are apparent at birth. In rare cases, severely affected individuals have abnormalities of internal organs such as a lung or a kidney, or the heart is abnormally located in the right side of the chest (dextrocardia).

Rarely, chest and hand abnormalities resembling those of Poland syndrome occur on both sides of the body, but researchers disagree as to whether this condition is a variant of Poland syndrome or a different disorder.

Causes and biological mechanisms

From: MedlinePlus Genetics, National Library of Medicine

The cause of Poland syndrome is unknown. Researchers have suggested that it may result from a disruption of blood flow during development before birth. This disruption is thought to occur at about the sixth week of embryonic development and affect blood vessels that will become the subclavian and vertebral arteries on each side of the body. The arteries normally supply blood to embryonic tissues that give rise to the chest wall and hand on their respective sides. Variations in the site and extent of the disruption may explain the range of signs and symptoms that occur in Poland syndrome. Abnormality of an embryonic structure called the apical ectodermal ridge, which helps direct early limb development, may also be involved in this disorder.

Rare cases of Poland syndrome are thought to be caused by a genetic change that can be passed down in families, but no related genes have been identified.

Inheritance and family implications

From: MedlinePlus Genetics, National Library of Medicine

Most cases of Poland syndrome are sporadic, which means they are not inherited and occur in people with no history of the disorder in their families. Rarely, this condition is passed through generations in families. In these families the condition appears to be inherited in an autosomal dominant pattern, which means one copy of an altered gene in each cell is sufficient to cause the disorder, although no associated genes have been found.

How common is it?

From: MedlinePlus Genetics, National Library of Medicine

Poland syndrome has been estimated to occur in 1 in 20,000 newborns. For unknown reasons, this disorder occurs more than twice as often in males than in females. Poland syndrome may be underdiagnosed because mild cases without hand involvement may never come to medical attention.

Reported clinical features and what the terms mean

The following findings are associated with this condition in Orphanet. They are not a checklist for diagnosing yourself, and they do not all occur in every affected person. Some are examination, imaging or laboratory findings that cannot be recognised at home.

The frequency labels describe how often a finding was reported among people with the condition in the source. They do not give the chance that a person with that symptom has the condition. Definitions below reproduce HPO terminology; they explain the term, not the likely severity in an individual.

Absence of subcutaneous fat · Very frequent (99-80%)

Lack of subcutaneous adipose tissue.

Aplasia of the pectoralis major muscle · Very frequent (99-80%)

Absence of the pectoralis major muscle.

Aplasia/Hypoplasia of the breasts · Very frequent (99-80%)

Absence or underdevelopment of the breasts.

Asymmetry of the thorax · Very frequent (99-80%)

Lack of symmetry between the left and right halves of the thorax.

Aplasia/Hypoplasia of the nipples · Very frequent (99-80%)

Abnormality of the hand · Frequent (79-30%)

An abnormality affecting one or both hands.

Absence of pectoralis minor muscle · Frequent (79-30%)

Aplasia (congenital absence) of the pectoralis minor.

Finger symphalangism · Frequent (79-30%)

An abnormal union between bones or parts of bones of the fingers. The synonymous term "symphalangism of the hand" may be translated as fusions of bones of varying digree, that involve at least one phalangeal bone of the hand. If bony fusions are referred to as "Symphalangism" the fusion occurs in a proximo-distal axis. Fusions of bones of the fingers in a radio-ulnar axis are referred to as "bony" Syndactyly.

Other findings in the same source

From: Orphanet

Additional reported features include Renal hypoplasia (Frequent (79-30%)); Small hand (Frequent (79-30%)); Unilateral brachydactyly (Frequent (79-30%)); Abnormal dermatoglyphics (Occasional (29-5%)); Abnormal humerus morphology (Occasional (29-5%)); Abnormal morphology of ulna (Occasional (29-5%)); Abnormal rib morphology (Occasional (29-5%)); Abnormal sternum morphology (Occasional (29-5%)); Abnormality of the liver (Occasional (29-5%)); Abnormality of the lower limb (Occasional (29-5%)). This is a selected summary, not a complete description of the condition.

Which doctor should you see?

The suggested department for discussing Poland syndrome is Clinical Genetics, with a clinical geneticist as the relevant type of clinician. Paediatrician (children) or physician (adults), with clinical geneticist referral.

This is an editorial referral starting point. The appropriate clinic depends on the person’s age, symptoms, previous diagnosis and local services. The first clinician can decide whether another specialty or a team is needed; a department label does not confirm the diagnosis.

How to prepare for an assessment

Bring a short timeline of the main symptoms: when they first appeared, whether they are constant or episodic, what seems to change them, and how they affect daily activities. Include previous reports, discharge summaries, current medicines and supplements, allergies, and any relevant family history. A dated record is more useful than trying to match every feature in an online article.

Ask the clinician what is already established and what remains uncertain. If a test is suggested, ask what question it answers, what its limitations are and how the result would change the next step. The information here is not an instruction to arrange every possible test. In children, bring growth, developmental and school information if it is relevant to the concern.

• Does the exact genetic or chromosome finding explain the observed features?
• Would a genetic counsellor help the family understand the result?
• Which organ-specific assessments are appropriate for this particular diagnosis?

Treatment discussions and follow-up

The material gathered for this draft does not provide a complete condition-specific treatment pathway for Poland syndrome. That gap does not mean that treatment is unavailable. A clinician needs to establish the diagnosis and review current guidance before recommending medicines, procedures, rehabilitation or other support.

Before leaving the appointment, clarify the next review date, who will communicate results, and whom to contact if the situation changes. Discuss difficulties with sleep, work, school, mobility, eating or emotional wellbeing when these are relevant. Practical support may require coordination between the treating clinician and other services.

The collected references do not establish a complete prevention or long-term outlook section for this entry. Missing information should not be interpreted as proof that prevention is impossible or that a particular outcome is inevitable. Ask what is known for the exact subtype, stage and personal circumstances, and which uncertainties remain.

When to seek emergency help

Severe breathing difficulty, collapse, new stroke-like symptoms, a seizure that is prolonged or repeated without recovery, uncontrolled major bleeding, or an immediate risk of self-harm require emergency help. In India, call 112 or reach the nearest emergency department. This is a general, non-exhaustive warning list; it is not a condition-specific triage tool.