Hemihypertrophy, now more commonly referred to as hemihyperplasia in the medical literature, is a condition in which one side of the body or a part of one side of the body is larger than the other to an extent considered greater than the normal variation. As it is difficult to establish a set clinical criteria for diagnosis of hemihyperplasia, the dictum is often used that the clinician should be able to see the asymmetry "from the end of the bed".
Hemihyperplasia is a congenital overgrowth disorder and the asymmetry can range from mild to severe. It is important to establish a diagnosis because hemihyperplasia is associated with an increased risk for embryonal tumors, mainly Wilms tumor and hepatoblastoma. Due to the heightened tumor risk, there is a tumor screening protocol that is recommended for all children with isolated hemihyperplasia and Beckwith-Wiedemann Syndrome. Some of the other syndromes associated with hemihyperplasia may also follow this tumor surveillance protocol. The recommended tumor surveillance protocol is:
- Any child with suspected isolated hemihyperplasia should be referred to a clinical geneticist for evaluation.
- Abdominal ultrasound every 3 months until 7 years
- Serum alpha fetoprotein measurement every 3 months until 4 years
- Daily caretaker abdominal examination at the discretion of the provider/parent
In some cases, children with hemihyperplasia may have different leg lengths. There are two main surgical options for the treatment of uneven leg lengths- shortening and lengthening. Epiphysiodesis, which involves removing part of the growth plate of the longer leg, allowing the shorter leg to "catch up", may be performed on patients still able to grow. Bone resection is performed on patients who have no growth left and involves removing part of the bone. Leg lengthening procedures are more painful, involving the insertion of pins to be turned, moving parts of the bone apart (Ilizarov's Method). This process is reserved mainly for patients with a discrepancy greater than 4 cm, although some leg lengthening procedures are now done cosmetically. Non-surgical options include attachment of a lift to the shoe, allowing the patient to walk normally.
Children with hemihypertrophy may also develop scoliosis, a curvature of the spine.
- ACMG Practice Guidelines, Diagnostic criteria and tumor screening for individuals with Isolated Hemihyperplasia, Carol L. Clericuzio, MD, and Rick A. Martin, MD, acmg.net
- Clericuzio CL (2009). "Diagnostic criteria and tumor screening for individuals with isolated hemihyperplasia". Genetics in Medicine. 11 (3): 220–2. doi:10.1097/GIM.0b013e31819436cf. PMID 19367194.
- Urban PP, Bruening R, Roland B (September 2009). "Congenital isolated hemifacial hyperplasia". J. Neurol. 256 (9): 1566–9. doi:10.1007/s00415-009-5148-9. PMID 19424770.
- Hemihypertrophy entry in the public domain NCI Dictionary of Cancer Terms
-  entry in the Children's Hospital of Boston website
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