Definition: A very rare benign tumor that may arise in many places, of which the most common is the oral cavity. The tumor is also called "granular cell myoblastomaâ€.
Prevalence: Extremely rare. This tumor occurs in females exclusively.
Etiology: It has been postulated that the etiology could be due to excessive production of estrogens by the fetal ovaries under hCG stimulation.
Ultrasound features: A large solid mass protruding from the fetal mouth. Polyhydramnios is evident due to inability of the fetus to swallow. Vascular connections between the tumor and oral floor may be demonstrated using Doppler technique.
 Cussen, L.J., MacMahon, R.A. Congenital granular cell myoblastoma. J Pediatr Surg 1975; 10:249-53
 Schwartz, Z., Katz, A., Zosmer, A., Dreasen, E., Lancet, M., Sagiv, M. Polyhydramnion caused by giant alveolar granular cell myoblastoma. Acta Obstet Gynecol Scan 1986; 65:519-521.