NASAL PROBOSCIS

Trunk-like appendage with one or two openings usually associated with an absent nose.

EMBRYOLOGY

• Thought to be due to a primary disorder of prechordal mesenchyme, resulting in abnormal induction of midfacial structures.
• Abnormal development of the nasal prominences may lead to fusion of the olfactory placodes and formation of a proboscis.
• Derangement in the development of medial facial structures may lead to different positions of the proboscis with respect to the eye(s).

ULTRASOUND

1. Cyclopia.
• Single or partly divided eye + single orbit.
• Arhinia with a proboscis.

2. Ethmocephaly.
• Marked hypotelorism.
• Arhinia with a proboscis.

3. Cebocephaly.
• Orbital hypotelorism.
• Proboscis-like nose but no median cleft lip / palate.

4. Single central opening to proboscis.

5. Inserted either above the orbit(s)
• Cyclopia or ethmocephaly (1)
6. Inserted normally between the orbits
• Cebocephaly (2).
7. Opening of proboscis has no connection with the choanae.
8. Ethmoid air cells, nasal conchae, nasal and lacrimal bones are usually absent.
9. Usually no cleft lip or palate (3).
10. Alobar holoprosencephaly (usually present). A proboscis has rarely been reported in the absence of alobar holoprosencephaly. In these cases there is usually unilateral nasal aplasia with a proboscis present in the position normally occupied by the absent nasal structures (4).
11. Usually single but bilateral proboscis has been reported.
12. Microcephaly.

REFERENCES

1. Filly RA, Chinn DH, Callen PW. Alobar holoprosencephaly: Ultrasonographic prenatal diagnosis. Radiology 1984;151:455.
2. Pilu G, Reece EA, Romero RA et.al. Prenatal diagnosis of craniofacial malformations with ultrasonography. Am J Obstet Gynecol 1986;155:45.
3. DeMyer W, Zeman W. Alobar holoprosencephaly (arhinencephaly) with median cleft lip and palate. Confin Neurol 1963;23:1.
4. Warkany J. Malformations in the respiratory tract. In: Congenital Malformations. Chicago, Year Book 1971:587-615.