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Clinicopathologic Reports, Case Reports, and Small Case Series
July 2001

Proboscis Lateralis

Author Affiliations
 

W. RICHARDGREENMD

Arch Ophthalmol. 2001;119(7):1071-1074. doi:

Proboscis lateralis describes a rudimentary nasal structure or appendage that is located off-center from the vertical midline of the face. Proboscis lateralis is a rare craniofacial malformation frequently associated with abnormalities of the eyes and/or ocular adnexa. We report a case with ipsilateral colobomatous microphthalmia and choanal atresia.

Report of a Case

A 3.5-kg black male infant was born at 40 weeks' gestation by uncomplicated spontaneous vaginal delivery with Apgar scores of 8 and 9 at 1 and 5 minutes. At birth, the patient was noted to have a 2.5 × 1.1-cm trunk-like appendage (Figure 1) arising from his left medial canthus with a clear mucoid discharge draining from an orifice at its distal end. Also noted were left microphthalmos, left choanal atresia, and a mildly hypoplastic left nasal ala. Prenatal history was negative for consanguinity, exposure to alcohol, ionizing radiation, prescription medications, or recreational drugs. The patient's mother denied any family history of blindness, craniofacial abnormalities, mental retardation, or other congenital defects. Chromosomal analysis was reported as 46, XY. Findings from examination of the left eye were remarkable for microphthalmia with a horizontal corneal diameter of 5.0 mm. The anterior chamber was well formed and the lens was clear. Funduscopic examination results were remarkable for a posterior chorioretinal coloboma with a partial retinal detachment. Findings from examination of the right eye were normal.

Figure 1.
Proboscis with metal/ skin hook
inserted into the distal orifice. Note the slightly hypoplastic left nasal
ala and obvious microcornea of the small left eye.

Proboscis with metal/ skin hook inserted into the distal orifice. Note the slightly hypoplastic left nasal ala and obvious microcornea of the small left eye.

Computed tomographic images (Figure 2 and Figure 3) demonstrated normal cerebral parenchyma, ventricular architecture, and mid-line anatomy. Hypoplasia of the left nasal passage with left-sided choanal atresia was present. A defect in the medial wall of the left orbit was noted, and a tubular soft tissue structure extended from the medial aspect of the preseptal soft tissue and appeared continuous with the nasal cavity and ethmoid sinus. The left globe was small and dysplastic with a colobomatous cyst posteriorly.

Figure 2.
Axial 1.5-mm contrast-enhanced
computed tomographic scan, bone windows. A, Left-sided choanal atresia (arrow).
B, Portion of the proboscis on the left (open arrow) with a pneumatized central
canal. The soft tissue extends through a defect (arrow) in the medial wall
of the left orbit, continuous with the ethmoid sinus.

Axial 1.5-mm contrast-enhanced computed tomographic scan, bone windows. A, Left-sided choanal atresia (arrow). B, Portion of the proboscis on the left (open arrow) with a pneumatized central canal. The soft tissue extends through a defect (arrow) in the medial wall of the left orbit, continuous with the ethmoid sinus.

Figure 3.
Axial 1.5-mm contrast-enhanced
computed tomographic scan, soft tissue windows. A, Cross-sectional view of
mid portion of tubular proboscis (open arrow). B, Oblique view closer to the
base of the proboscis, which protrudes from soft tissue adjacent to the medial
canthus. Note air in the central canal (open arrow). The left globe is microphthalmic,
and a colobomatous defect (arrow) is present with a cystic mass extending
posteriorly.

Axial 1.5-mm contrast-enhanced computed tomographic scan, soft tissue windows. A, Cross-sectional view of mid portion of tubular proboscis (open arrow). B, Oblique view closer to the base of the proboscis, which protrudes from soft tissue adjacent to the medial canthus. Note air in the central canal (open arrow). The left globe is microphthalmic, and a colobomatous defect (arrow) is present with a cystic mass extending posteriorly.

Surgical excision of the proboscis was performed at age 4 months. Since the nasal alae were relatively well developed, reconstruction was unnecessary, and the soft tissue appendage was simply amputated from its origin at the superior aspect of the left medial canthus. The fistulous tract to the ethmoid sinus was excised, and the choanal atresia was then repaired.

Pathologic findings revealed an oblong, skin-covered, tubular mass (Figure 4) measuring 2.5 cm in length × 1.1 cm in greatest diameter. At the distal end of the appendage was a 3-mm orifice that was patent to probing. Microscopic examination of sections from the mass (Figure 5 and Figure 6) revealed a hamartomatous malformation covered by hair-bearing skin. The stromal soft tissues were noted to be composed of fibroadipose tissue with abundant bundles of skeletal/ muscle. A central canal was lined by squamous mucosa distally, changing to respiratory-type mucosa more proximally. Small plates of hyaline cartilage as well as several normal-appearing peripheral nerves were noted in the soft tissues adjacent to the central canal.

Figure 4.
A, Resected proboscis. B, Whole-mount
section showing fibroadipose stromal soft tissues containing skeletal/ muscle
and surrounding a meandering central canal (hematoxylin-eosin, original magnification).

A, Resected proboscis. B, Whole-mount section showing fibroadipose stromal soft tissues containing skeletal/ muscle and surrounding a meandering central canal (hematoxylin-eosin, original magnification).

Figure 5.
Transverse cross section of the
proboscis at its base revealing a mucosa-lined central canal with clusters
of submucosal glands and plates of hyaline cartilage (hematoxylin-eosin, original
magnification ×65).

Transverse cross section of the proboscis at its base revealing a mucosa-lined central canal with clusters of submucosal glands and plates of hyaline cartilage (hematoxylin-eosin, original magnification ×65).

Figure 6.
The mucosal surface varied from
cuboidal/low columnar at the base (A) to hyperplastic variably ciliated pseudostratified
columnar epithelium more distally (B) and to stratified nonkeratinizing squamous
mucosa near the skin surface (hematoxylin-eosin, original magnification ×160).

The mucosal surface varied from cuboidal/low columnar at the base (A) to hyperplastic variably ciliated pseudostratified columnar epithelium more distally (B) and to stratified nonkeratinizing squamous mucosa near the skin surface (hematoxylin-eosin, original magnification ×160).

Comment

Proboscis lateralis is a rare congenital anomaly in which a tubular, nose-like structure is seen to arise from the medial canthal area. Proboscis lateralis was first mentioned in 1861 by Forster in his monograph Congenital Malformations of the Human Body1 in which he described an 8-month-old girl with a proboscis emanating from her left frontal area, heminasal aplasia, and a depression between her 2 normal eyes that was surrounded by eyelids complete with both eyelashes and a conjunctival lining. Selenkoff, however, is often credited with first describing proboscis lateralis in an 1884 autopsy.2

Although it was initially reported that no sex predilection existed,3 Boo-Chai2 noted a 2:1 male-female preponderance. Review of 9 cases subsequent to Boo-Chai's report supports the notion of a male preponderance with a 3:1 male-female ratio.39 There does not seem to be any racial predilection in proboscis lateralis.

The embryologic defect that results in proboscis lateralis appears to involve the nasal placode, which is a primary organizer of the nasal area of the midface. Duplication of the nasal placode, which is very rare, may generate a lateral proboscis in the absence of any other facial anomalies. Usually, however, the nasal placode develops abnormally, which may result in legion midfacial anomalies, but continues to act on mesenchymal tissue, allowing it to fuse into the tubular lateral proboscis.

Although the proboscis generally arises from the area of the medial canthus, exceptionally rare cases have been described in which the anomalous structure arises from the lateral canthus,4 nasal root,2 chin,10 or is present bilaterally.11 This trunk-like appendage is generally 2 to 3 cm in length and 1 cm in diameter and has a central tract lined with respiratory epithelium. The tract drains at a dimpled opening at the distal end of the proboscis and may be continuous with the paranasal sinuses proximally. Generally, there is heminasal hypoplasia or aplasia on the side of the proboscis although, in rare cases, the nose is normal. Anomalies often affect the nasal cavity as well as the nares, and complete closure of the nasal cavity at the piriform aperture may be seen in cases in which heminasal aplasia is present.2 Cleft lip and/or palate may also be present. To the best of our knowledge, this is the first reported case of proboscis lateralis associated with choanal atresia.

Of interest to the ophthalmologist is the frequent association of abnormalities of the eye and ocular adnexa with proboscis lateralis. Although Wang et al9 reported that ocular defects are rare in patients with proboscis lateralis, a subsequent review of the literature by Boo-Chai2 noted that 24 of 34 patients with proboscis lateralis had associated anomalies of the ipsilateral eye and/or ocular adnexa. These abnormalities included anophthalmia, microphthalmia, microcornea, lenticular opacities, cyclopean eye, and colobomas of the choroid, retina, iris, and eyelids. The presence or absence of ocular abnormalities was used by Boo-Chai2 to help categorize patients with proboscis lateralis into 4 groups: group I has a lateral proboscis with a normal nose (but may have ocular findings); group II, lateral proboscis with an ipsilateral deformity of the nose; group III, ipsilateral deformity of the nose and the eye and/or ocular adnexa; and group IV, cleft lip and/or palate in addition to the nasal and ocular abnormalities.

It is noteworthy that most patients with proboscis lateralis do not have serious central nervous system abnormalities, in stark contrast to a mid-line proboscis, which is often indicative of holoprosencephaly. Nonetheless, proboscis lateralis may coexist with central nervous system anomalies,4,12 and early neuroimaging is indicated to rule out intracranial abnormalities.

Because there is some variability in facial anomalies and the degree of nasal hypoplasia seen with proboscis lateralis, management must be individualized. When marked hypoplasia or aplasia of the nasal ala is present, reconstruction is indicated. The structure and texture of the proboscis make it an ideal substrate for nasal reconstruction, and for this reason, the proboscis should not be excised if future nasal reconstruction is anticipated. Depending on the size and location of the proboscis and the degree of nasal hypoplasia, a variety of techniques may be used to reconstruct an aesthetically acceptable nare, including use of the proboscis as a pedicle flap.2,3,57,13,14

In our patient, ipsilateral nasal hypoplasia was minimal, and simple amputation of the proboscis and excision of the fistula connecting it to the ethmoid sinus was appropriate. However, endoscopic repair of the choanal atresia was complicated by the narrow nasal opening and required conversion to a transpalatal approach. At one time, it was suggested that the affected eye be enucleated to prevent formation of a fistula to the meninges and subsequent meningitis. There is no evidence, however, that such communication occurs, and enucleation is not recommended unless tumor is suspected.

Because of the variety of maxillofacial and ocular disease seen with proboscis lateralis, optimal care of the patient warrants a multidisciplinary approach that may involve an otolaryngologist or oromaxillofacial surgeon, plastic surgeon, and ophthalmologist.

This study was supported in part by an unrestricted grant from The Foundation for Research to Prevent Blindness, New York, NY, and the Alabama Eye Institute, Birmingham.

The authors have no financial interest in the subjects of this article.

Corresponding author and reprints: Martin S. Cogen, MD, Suite 601, 700 18th St S, Birmingham, AL 35233.

References
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