Midline Cervical Cleft |
| Midline
cervical cleft is a rare congenital malformation of the ventral neck
that, despite being recognized for more than a century and a half,
remains unfamiliar enough to many clinicians that it is frequently
overlooked or misclassified at the moment of presentation. The lesion
was first documented in the mid-nineteenth century, described in
greater detail in the early twentieth century under the heading of
thyroglossal anomalies, and given its current name in the 1950s. Even
now the total experience recorded in the world literature is modest,
amounting to only a few hundred reported cases, and its true frequency
is uncertain because isolated instances are often considered too
trivial to publish. Available estimates place it at roughly one to two
percent of congenital anterior neck defects, with one population-based
approximation suggesting an occurrence on the order of one in seventy
thousand births. Historically a female predominance of up to two to one
was proposed, but larger pooled analyses have found the sexes affected
almost equally, and one extensive review even reported a slight male
excess, so that no convincing sex predilection can currently be
claimed. A tendency toward higher frequency in individuals of European
ancestry has been suggested but rests on limited data. The malformation is present from birth, although its subtlety in the neonate means the diagnosis may not be made until infancy, when impaired neck mobility becomes apparent. The classic presentation is a triad. Cranially there is a small nipple-like or hood-like skin tag; along the midline there is a linear atrophic groove of dysmorphic or absent skin, most often lined by a reddened, desquamating epithelium; and caudally there is a blind-ending sinus or pit that may intermittently discharge mucoid or serous fluid. Beneath the atrophic surface lies the anatomical feature of greatest clinical importance, a fibrous cord that runs longitudinally from the region of the mandibular symphysis to the sternum or manubrium. This cord, together with the paucity of overlying skin, tethers the anterior neck, producing a web, limiting extension, and effacing the normal cervico-mental angle. Over time the traction transmitted to the developing mandible can generate a bony spur, encourage mandibular hypoplasia and retrognathia, and contribute to an open-bite tendency and an appearance of micrognathia. Not all three components of the triad are invariably present; pooled data indicate that most patients display the full triad, while a minority present with only one or two elements, the linear atrophic groove being the most consistent finding and the caudal sinus and cephalic nodule somewhat less frequent. The embryological basis remains debated, but the most widely accepted hypothesis attributes the defect to failure of midline fusion of the first and second, and possibly the third, branchial arches during the third and fourth weeks of intrauterine development. In this model, a persistent midline furrow allows abnormal deposition and migration of mesodermal cells within the ectoderm, which then differentiate into the skeletal muscle, glandular tissue, and mucosal surface characteristic of the lesion. Competing theories have invoked a bronchogenic origin, persistence of thyroglossal remnants, vertical outgrowth of tongue musculature, pressure necrosis from the pericardial roof, and localized vascular ischemia, none of which fully accounts for the consistent anatomy or histology. The condition is regarded as a caudal variant of the number 30 facial cleft in the standard craniofacial classification, and although it is overwhelmingly sporadic, a small number of familial occurrences, including transmission between a grandparent and grandchild, have prompted genetic study. Exome analyses have suggested a polygenic contribution, with reported associations involving loss of a pregnancy-associated plasma protein and mutations affecting several candidate genes, but no single causal mutation has been established. Histopathology varies by region of the specimen. The cephalic tag typically shows normal skin, sometimes with cartilage or muscle. The linear cleft demonstrates keratinized stratified squamous epithelium with parakeratosis and a characteristic absence of epithelial adnexa in the dermis, with fibrosis replacing the superficial musculature. The caudal tract is lined by pseudostratified ciliated columnar epithelium, at times of respiratory type, and contains seromucinous glands that explain the mucoid discharge. A more recent and clinically consequential observation is that the subcutaneous cord is not merely fibrous but frequently contains a bundle of mature striated muscle lying superficial to the platysma, in the plane normally occupied by subcutaneous fat. This contractile band, demonstrable by its response to cautery and by imaging, appears to be the true agent of neck tethering, and its previous under recognition is thought to explain many of the recurrences reported after incomplete surgery. Because the diagnosis is essentially clinical, imaging is used chiefly to confirm the lesion and exclude concurrent pathology rather than to establish the diagnosis. Ultrasonography is the reasonable first-line modality, being noninvasive and well tolerated, and it typically shows an avascular blind-ending sinus tract with an associated fibrous band in the dermis while allowing assessment of the thyroid and adjacent structures. Cross-sectional imaging is reserved for atypical presentations, suspected associated anomalies, or surgical planning; magnetic resonance imaging characteristically reveals thinning of the epidermis and a linear tract that is hypointense on T1 and hyperintense on T2 without involvement of deep bony or cartilaginous structures. The principal entities in the differential diagnosis are thyroglossal duct cyst, which elevates with tongue protrusion and swallowing and relates to the hyoid, and branchial cleft anomalies, which are usually lateral, along with dermoid and epidermoid cysts. Associated malformations, when they occur, include clefting of the lip, mandible, tongue, or sternum, absence of portions of the hyoid or thyroid cartilage, and, more rarely, midline hemangioma and cardiac defects, so inspection of the oral cavity, tongue, and chest is prudent. Treatment is surgical, and the cardinal principle on which the literature is unanimous is that the entire lesion, and above all the fibrous or fibromuscular cord, must be excised completely; mere transection or partial resection reliably produces recurrence and persistent contracture. Early intervention, generally advocated before one year of age and by some authors within the first months of life, is favored because the lesion is smaller and less mature, the resection and resulting scar are minimized, and growth restriction of the mandible may be limited. The closure technique remains the chief area of debate. Simple linear closure can suffice for small, immature lesions when adjacent tissue is lax and no established contracture is present, but it carries a higher risk of recurrent contracture and vertical scar banding. Consequently most surgeons employ some geometric closure, with single, double, or opposing Z-plasty being the most common, since these lengthen the contracted midline, reorient the scar into natural skin creases, and help recreate the cervico-mental angle; W-plasty has also been used successfully. Hypertrophic scarring is the most frequently encountered complication, particularly along the limbs of a Z-plasty, while recurrence has been observed almost exclusively when excision was incomplete or a straight-line repair was chosen. Long-term morphometric follow-up suggests that after release the chin grows at a normal rate but shows no catch-up, remaining somewhat posteriorly displaced, leaving unresolved whether the retrognathia reflects an intrinsic developmental defect or the mechanical legacy of the cord. In sum, midline cervical cleft is a rare but clinically distinctive anomaly whose recognition depends on appreciating its characteristic triad and its tethering cord. Prompt clinical diagnosis, judicious use of ultrasonography, and early complete excision of the fibrous and muscular band, followed by a tension-free geometric closure, offer reliable restoration of neck contour and mobility and minimize the functional and esthetic sequelae that otherwise accrue with age. References: 1- D'Souza JN, Valika T, Maddalozzo J. Surgical management of midline cervical cleft. Int J Pediatr Otorhinolaryngol. 127:109657, 2019 2- Çelikoyar M, Aktan E, Dogusoy G. Congenital midline cervical cleft: a case report. J Med Case Rep. 13(1):176. 2019 3- Riba M, Bejarano M, Hernández C, Moraleda I, Massaguer C, Ribalta T, Gómez M, Krauel L, Parri FJ, Albert A. Midline Cervical Cleft: An Anatomical Finding and a Proposal for a New Approach. Cleft Palate Craniofac J. 57(12):1422–1427, 2020 4- Moreno SD, Christopher P, Kloostra P. Congenital Midline Cervical Cleft (CMCC): Z-Plasty Versus Linear Cutaneous Repair. J Craniofac Surg. 34(1):e38–e41, 2023 5- Magalhães R, Louro M, Forny D, Sá Á, Franco D. Congenital midline cervical cleft: Management of a case series and literature review. J Plast Reconstr Aesthet Surg. 93:117–126, 2024 6- Hwang JC, Perry R. Midline Cervical Cleft: Case Report and Current Understanding. Cleft Palate Craniofac J. 62(12):2180–2186, 2025 |
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