What is the role of hemihyperplasia in the etiology of pheochromocytomas?

Updated: Aug 10, 2018
  • Author: Michael A Blake, MBBCh, MRCPI, FRCR; Chief Editor: George T Griffing, MD  more...
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Although its genetics remain incompletely understood, hemihyperplasia (also called hemihypertrophy) is known to increase tumor risk. The condition may be an isolated finding or a part of a larger syndrome such as Beckwith-Wiedemann syndrome, Proteus syndrome, or neurofibromatosis. The tumors most commonly associated with hemihyperplasia are Wilms tumor and hepatoblastoma, but at least one patient has been described with isolated hemihyperplasia and an adrenal pheochromocytoma on the hyperplastic side. [20]

Hemihyperplasia can be caused by paternal uniparental disomy for the 11p15 chromosomal region, as can be seen in isolated hemihyperplasia and Beckwith-Wiedemann syndrome. Methylation of the LIT1 and H19 genes is important to the pathogenesis of hemihyperplasia and underscores the importance of epigenetics in normal growth and in the development of neoplasia.

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