Hemihypertrophy

• Hemihypertrophy is a rare condition causing one side of the body to grow larger than the other.
• It can affect external body parts and internal organs, leading to visible asymmetry.
• The condition is often linked to genetic syndromes like Beckwith-Wiedemann Syndrome.
• Diagnosis involves clinical examination, imaging, and genetic testing.
• Management focuses on regular screening for associated tumors and addressing physical discrepancies.

What is Hemihypertrophy?

Hemihypertrophy refers to a congenital condition where there is an abnormal overgrowth of one side of the body or a specific body part. This growth difference can be subtle or pronounced, leading to noticeable asymmetry. It is a rare disorder, often present at birth or becoming apparent in early childhood, and can affect any part of the body, including limbs, the face, trunk, and even internal organs. While sometimes isolated, it is frequently a feature of underlying genetic syndromes, which carry additional health implications.

The condition is not a disease in itself but rather a physical manifestation that signals a potential underlying genetic or epigenetic alteration. The exact prevalence is difficult to determine due to its varied presentation and association with multiple syndromes, but it is considered uncommon. Early recognition is crucial because individuals with hemihypertrophy have an elevated risk of developing certain childhood cancers, particularly Wilms tumor (a kidney cancer) and hepatoblastoma (a liver cancer).

Symptoms and Causes of Hemihypertrophy

The primary hemihypertrophy symptoms causes revolve around the noticeable difference in size between the two sides of the body. Symptoms can vary widely in severity and location. Common manifestations include:

• One limb (arm or leg) being longer or thicker than the other.
• Asymmetry of the face, with one side appearing larger.
• Overgrowth of one side of the trunk.
• Enlargement of internal organs, such as the kidney or liver, on one side.
• Differences in shoe or glove size between the left and right sides.

The causes of hemihypertrophy are often complex and multifactorial. In many cases, it is sporadic, meaning it occurs without a clear family history. However, it is frequently associated with specific genetic syndromes. The most common underlying cause is Beckwith-Wiedemann Syndrome (BWS), a genetic disorder characterized by overgrowth, abdominal wall defects, and an increased risk of childhood tumors. Other syndromes linked to hemihypertrophy include Sotos Syndrome, Proteus Syndrome, and isolated hemihypertrophy (which is not part of a recognized syndrome but still carries tumor risk). These conditions typically involve genetic mutations or epigenetic changes that affect growth-regulating genes, leading to uncontrolled cellular proliferation in specific tissues on one side of the body.

Diagnosis, Treatment, and Management of Hemihypertrophy

The hemihypertrophy diagnosis treatment pathway begins with a thorough clinical evaluation. Diagnosis is primarily based on physical examination, noting the characteristic asymmetry. Imaging studies, such as ultrasound, MRI, or CT scans, are often used to assess the extent of overgrowth, particularly in internal organs, and to screen for associated tumors. Genetic testing is crucial to identify underlying syndromes like Beckwith-Wiedemann Syndrome, which guides further management and risk assessment. For instance, children with BWS are recommended for regular screening for Wilms tumor and hepatoblastoma.

Treatment for hemihypertrophy is largely supportive and focuses on managing symptoms and mitigating associated risks. There is no cure for the overgrowth itself. A multidisciplinary approach involving pediatricians, geneticists, oncologists, orthopedic surgeons, and other specialists is often necessary. Key aspects of management include:

Regular tumor surveillance is paramount, especially in early childhood. For example, children with Beckwith-Wiedemann Syndrome typically undergo abdominal ultrasounds every three months until age eight to screen for Wilms tumor, and alpha-fetoprotein (AFP) blood tests every six weeks until age four for hepatoblastoma, as recommended by organizations like the American Academy of Pediatrics. Orthopedic interventions may be required for significant limb length discrepancies, ranging from shoe lifts to surgical procedures like epiphysiodesis (slowing growth in the longer limb) or limb lengthening in severe cases. Cosmetic surgery may be considered for facial or other visible asymmetries, though this is often deferred until growth is complete.

Living with hemihypertrophy involves ongoing medical monitoring and support. Individuals and families benefit from genetic counseling to understand the condition and its implications. Psychological support can also be valuable to help cope with body image concerns and the challenges of managing a chronic condition. Educational resources and patient advocacy groups play a significant role in providing information and fostering a sense of community for those affected by this rare disorder.