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2007-09-05-15 Proboscis lateralis © Bircher www.thefetus.net/
Proboscis lateralis

Ana Bircher, MD.

Inner Vision Women"s Ultrasound, Nashville, TN, USA.   


Synonyms

Lateral proboscis, heminasal proboscis [1], lateral nasal proboscis [11].

Definition

Lateral proboscis is a rare craniofacial malformation characterized by a rudimentary tubular, nose-like structure located off-center from the vertical midline of the face, most of the cases arising from the medial portion of the orbital roof [ 2-5].

It has been reported to occur sporadically as an isolated defect, or to occur in association with a wide spectrum of other anomalies, including heminasal aplasia spectrum, proboscis and heminasal aplasia/atypical clefting syndrome, and the “short stature, mental retardation, callosal agenesis, heminasal hypoplasia, microphthalmia, and atypical clefting” syndrome [6, 7].

History

The diagnosis was first described by Foster in his monograph entitled “Congenital Malformations of the Human body” in 1861. He described an 8-month-old girl with the lateral proboscis, heminasal aplasia, and cyclopean eye. [1,7]. Later in 1884, Selenkoff reported this anomaly in the autopsy findings of a 34-year old Finnish farmer [3,7].
Koo provided a review of 34 cases published in the literature between1884 and 1894 and classified the lateral proboscis in four groups depending on severity of clinical presentation (see below) [7].
In other review, Van Kempen et al. collected 18 cases reported between 1972 and 1996.
Since the earlier documentation of this condition, several reports and literature reviews of lateral proboscis occurring in combination with various craniofacial abnormalities have been published [1-7].

Classification

The classification of lateral proboscis suggested by Koo is the following:

    • Group I: lateral proboscis with normal nose (least common);

    • Group II: lateral proboscis with an ipsilateral deformity of the nose (second in frequency);

    • Group III: lateral proboscis with ipsilateral deformity of the nose, eye and or ocular adnexa (the most common type);

    • Group IV: lateral proboscis with ipsilateral deformity of the nose, eye and or ocular adnexa, plus cleft lip and/or palate.

Etiology

Lateral proboscis is a rare anomaly, with a reported incidence to be less than 0.1:10,000 [8]. Some authors described this condition in  consanguineous parents, which might suggest an autosomal recessive mode of inheritance. Incidence in male appears to be higher than in females, with a 3:1 male/female ratio. [2] The reason for this sex difference is unknown.

Pathogenesis

There is no consensus regarding the pathogenesis of the lateral proboscis; however it appears that it is a developmental defect involving the nasal placode, which is the primary organizer of the nasal area of the midface [2, 11]. And since nasal development occurs concomitantly with development of the face and palate, they are considered an embryological unit, and any congenital anomaly of the nose can be associated with anomalies of the face and palate, as well as other midline face anomalies [1,4,8,13].

It has been postulated that lateral proboscis is included in a spectrum of malformations described as developmental field defects. This terminology refers to those conditions which represent an embryological area where an error causes a major anomaly which, in turn, disturbs contiguous developing areas. It occurs more often in the midline [10].

Review of the embryologic concepts

By the end of the third week of gestation, the neural tube is formed, the cephalic end of which becomes the primary brain vesicle. In the cephalic region, condensations of mesoderm on either side of the midline become the paraxial mesoderm. Facial development occurs mainly between the fourth and eight weeks. By 4 1/2 weeks, a centrally located stomodeum appears, and it becomes surrounded by a pair of maxillary and mandibular prominences, as well as a single frontal prominence.

The formation of the nasal cavity starts with the nasal placodes, which appear by the end of the fourth week as bilateral oval thickenings of the surface ectoderm on the inferolateral region of the frontal prominence (frontonasal process). The process of conversion of the nasal placodes to the primitive nasal pits, occur at the 10-mm stage of embryonic development, early in the fifth week. It is at this stage where insult causing lateral proboscis probably occurs [2,3].
Initially these placodes are convex, but later they are stretched to produce a flat depression, which will form the nasal (olfactory) pits. These pits are originally widely spaced on the anterolateral sides of the developing head of the embryo. In later developmental stages, the nasal pits grow towards the midline. Three processes grow around both nasal pits: the maxillary, the medial and lateral nasal prominences [11].
The maxillary and lateral nasal processes fuse to form the nostrils. The medial nasal processes fuse together, thereby forming the ridge, tip, and columella of the nose as well as the philtrum and medial part of the upper lip. By fusion with the maxillary processes, the medial nasal processes separate the cavities of the nose and mouth. The nasal pits invaginate further and break through into the oral cavity. Absence of one of the nasal placodes leads to heminasal aplasia, which is a frequent finding associated to lateral proboscis [12]. The medial nasal folds grow caudally and fuse with the frontonasal process.
Some theories postulate that lateral proboscis might represent a developmental failure of the medial and lateral nasal prominences, but with normal development of the nasal placode. This would results in the fusion of the maxillary prominence of the affected side to the contralateral nasal prominence. The association of absence or hypoplasia of the nasal cavity and paranasal sinuses on the affected side, as well as the anomalies in the nasolacrimal system (frequently associated with lateral proboscis) might be explained due to the close relationship of these structures with the maxillary and lateral nasal prominences. Blindly ending nasolacrimal ducts may result in cyst formation.
Since the nasal placode is also responsible for the formation of olfactory nerves and induces the differentiation of the rhinencephalon and cribriform plate, these structures can also be abnormal in lateral proboscis spectrum [5].
By the same thought, the occurrence of encephaloceles with lateral proboscis is explained by the close relationship between the primary brain vesicle and the developing nasal placode. Two main types of encephaloceles occur in the nasomaxillary region: frontonasal or frontoethmoidal, depending on their relationship to the nasal bone. In cases of lateral proboscis in which the nasal and ethmoid cavities are absent, an orbit encephalocele may develop. The enlarging intraorbital encephalocele interferes with the normal development of the orbital contents, including the globe and optic nerve. In addition, glial tissue of the olfactory bulb can get sequestered within the orbit and result in an intraorbital glioma. [1]

Other theories trying to explain the cause of lateral proboscis postulate that the defect would be not just developmental failure of the nasal prominences but to imperfect fusion of the lateral nasal wall and maxillary process [1,13]. Paramedian facial clefts could be explained by this mechanism.

Clinical features

The clinical presentation of the proboscis is a typically obvious deformity of the facial structures, which can be diagnosed at birth or prenatally by ultrasound [22].  It consists of a 2-3 cm long and 1 cm in diameter, soft tissue trunk-like process that originates from the medial portion of the orbital roof [3,4,8,13,14]. It is club shaped distally and usually contains an internal canal that transverse the entire proboscis and ends proximally in a cul-de-sac. The canal is a small tract lined by stratified columnar epithelium running along its centre, which might be continuous with the paranasal sinuses proximally, and drains into a dimple at its distal end. The proboscis is regarded as containing the soft part of the nose.
Although the proboscis generally arises from the area of the medial canthus, exceptionally rare cases have been described in which it arises from the lateral canthus, nasal root, chin, or is present bilaterally [13]. In most cases there is heminasal hypoplasia or aplasia associated 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 opening may also be seen.

Other facial and cerebral anomalies which may accompany the lateral proboscis spectrum include:

Eyes:  ipsilateral anophthalmia, iris coloboma, upper and lower lid cleft, and choroidal cleft occur in about 44% of these patients [8]. Other ocular findings include microphthalmia, microcornea, hypoplastic optic globe, hypoplastic optic nerve, cystic degeneration of the optic nerve, orbital cysts, lenticular opacities, cyclopean eye, and colobomas of the choroid, retina and eyelids, and abnormal lacrimal canal with excessive lacrimation.

Facial bone anomalies, other than nasal bone anomalies, occur in 38% [8].

Nose: choanal atresia, abnormalities in the vomer and ethmoid bones, abnormal nasal pyramid, absent nasal bone.

Face: cleft lip and/or palate, lateral facial clefts, unilateral lipoma.

Brain: Brain and cranial vault anomalies are associated in 19% of patients [8]. These include meningoencephalocele, sphenoorbital basal cephalocele, arachnoid cyst, brain stem asymmetry [1,2,5,7-9,11,13,15-18].

Lateral  proboscis with or without heminasal aplasia appears to be the mild end of the spectrum of f heminasal aplasia/atypical clefting syndrome [6].

Lateral proboscis is a developmental field defect, involving only facial and cranial structures, however a rare case of bilateral proboscis associated with right oscheohydrocele (scrotal hydrocele) and undescended testis was described [9].

Pathological findings

All normal tissues found in the nose may be present in the proboscis [8].

Diagnosis

Prenatal diagnosis of lateral proboscis has been documented in few cases. It is important to highlight the impact of early diagnosis and adequate counseling, since its prognosis and management are different from other types of proboscides [20].

Management

The treatment for lateral proboscis is surgical repair after complete facial growth. However, due to the complex nature of this malformation, achieving an esthetic result is often a challenge. A prosthetic is suitable management until final repair and reconstruction are possible.
Due to the frequent associated anomalies, a multispecialty team, including staff from the otolaryngology, ophthalmology, neurosurgery, and plastic surgery departments should evaluate the patient prior to surgical repair.
Neuroimaging studies, looking for brain anomalies is also recommended [1]. The proper timing and sequencing of reconstruction using a multidisciplinary team approach are essential [8].
One report raises the question of unusual cystic re-growth of the remnants of a proboscis lateralis after inadequate excision [12].
There are several nasal reconstruction methods using the proboscis as a donor. These techniques are beyond the scope of this article, but I refer the lector to the following the references. [1,7,13,21-23].

Prognosis

Normal developmental outcome is the rule, unless brain abnormalities are also seen. Meanwhile a midline proboscis is often indicative of holoprosencephaly, lateral proboscis rarely presents with associated CNS abnormalities. Holoprosencephaly was only described accompanying an oblique facial cleft, an anterior encephalocele in which the lateral proboscis occurred in an unusual, very lateral location [24]. Esthetic and psychological problems are often concern of the patient and families.

References

1. Boahene DK, Bartley GB, Clay RP, Thompson DM. Heminasal proboscis with associated microphthalmos and encephalocele.J Craniofac Surg. 2005 Mar;16(2):300-6.
2. John Guerrero, MD; Martin Cogen, MD; David Kelly,MD; Brian Wiatrak, MD. Clinicopathologic Reports, case reports, and small case series. Ptoboscis lateralis. Archives Ophthalmology 2001;vol 119, July 2001: 1071- 1080.
3. Abou-Elhamd KE, Al-Hewaige MT. Proboscis lateralis: clinical and radiological features. J Laryngol Otol. 2005 Feb;119(2):158-60.
4. Yildirim SV, Unal M, Barutçu O. Proboscis lateralis: a case report Int J Pediatr Otorhinolaryngol. 2001 Nov 1;61(2):179-82.
5. Acarturk S, Kivanc K, Atilla E, Sekucoglu T. Proboscis lateralis: evaluation of the anomaly and a review of two cases. Plast Reconstr Surg. 2006 Jun;117(7):140e-146e OMIM. Online. Mendelian Inheritance in Man.-www.ncbi.nlm.nih.gov/sites/entrez.
6. Khoo BC. The proboscis lateralis--a 14-year follow-up. Plast Reconstr Surg. 1985 Apr;75(4):569-77
7. Belet N, Belet U, Tekat A, Küçüködük U. Proboscis lateralis: radiological evaluation. Pediatr Radiol. 2002 Feb;32(2):99-101. Epub 2001 Dec 8.
8. Harada T, Muraoka M. Proboscis lateralis: a rare bilateral case. Ann Plast Surg. 2001 Sep;47(3):350-1.
9. Hall, Bryan D.; Malformations and dysmorphology: terminology, principles, and examples. Online Medical Genetics Board review course. 2007. University of Pittsburg.
10. Moore, K; Persaud, T.V.N. The developing human. Clinically oriented embryology. 6th. Edition. W.B.Saunders Company,1998.
11. Mladina R, Manojlović S, Markov-Glavas D, Subarić M. An unusual case of heminasal aplasia: proboscis lateralis or cystic teratoma? J Craniofac Surg. 2003 Jan;14(1):41-5.
12. Van Kempen AA, Nabben FA, Hamel BC. Heminasal aplasia: a case report and review of the literature of the last 25 years. Clin Dysmorphol. 1997 Apr;6(2):147-52.
13. Wang SJ, Wang YW, Roy FH. Proboscis lateralis, microphthalmos, and cystic degeneration of the optic nerve. Ann Ophthalmol. 1983 Aug;15(8):756-8.
14. Mugaddu EG. Proboscis lateralis--a rare congenital anomaly. A case report. S Afr Med J. 1985 Jul 6;68(1):45.
15. Poed LB, Hochhauser L, Bryke C, Streeten BW, Sloan J. Proboscis lateralis with associated orbital cyst: detailed MR and CT imaging and correlative embryopathy. AJNR Am J Neuroradiol. 1992 Sep-Oct;13(5):1471-6.
16. Galante G, Dado DV. The Tessier number 5 cleft: a report of two cases and a review of the literature. Plast Reconstr Surg. 1991 Jul;88(1):131-5.
17. Garabedian EN, Ducroz V, Leperchey F, Roger G, Denoyelle F. Malformations of the nasal fossa and paramedian facial clefts. New perspectives. Ann Otolaryngol Chir Cervicofac.
18. Guion-Almeida ML, Richieri-Costa A. New syndrome of growth and mental retardation, structural anomalies of the central nervous system, and first branchial arch, anophthalmia, heminasal a/hypoplasia, and atypical clefting: report on four Brazilian patients. Am J Med Genet. 1999 Nov 26;87(3):237-44.
19. Mehta L, Petrikovsky B, Tydings L, Lundberg J. Lateral nasal proboscis: antenatal diagnosis and counseling. Obstet Gynecol. 1999 Nov;94(5 Pt 2):815-7.
20. J.K. Chong and L.M. Cramer, Proboscis lateralis: staged management with a four-year follow-up. Ann Plast Surg 1978 March;1(1):225–228.
21. Uğurlu K, Karşidag S, Ozçelik D, Sadikoğlu B, Baş L.Repair of proboscis lateralis. Scand J Plast Reconstr Surg Hand Surg. 2005;39(3):184-7.
22. Eroğlu L, Uysal OA. Proboscis lateralis: report of two cases. Br J Plast Surg. 2005 Jan;58(1):124-5.
23. Antoniades K, Baraister M. Proboscis lateralis: a case report. Teratology. 1989 Sep;40(3):193-7.

 

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