Hairline indicators of craniofacial clefts

Dysembryogenetic Pathogenesis of Basal Cell Carcinoma: The Evidence to Date

The Basal Cell Carcinoma (BCC) is a sort of unique tumour due to its combined peculiar histological features and clinical behaviour, such as the constant binary involvement of the epithelium and the stroma, the virtual absence of metastases and the predilection of specific anatomical sites for both onset and spread. A potential correlation between the onset of BCC and a dysembryogenetic process has long been hypothesised. A selective investigation of PubMed-indexed publications supporting this theory retrieved 64 selected articles published between 1901 and 2024. From our analysis of the literature review, five main research domains on the dysembryogenetic pathogenesis of BCC were identified: (1) The correlation between the topographic distribution of BCC and the macroscopic embryology, (2) the correlation between BCC and the microscopic embryology, (3) the genetic BCC, (4) the correlation between BCC and the hair follicle and (5) the correlation between BCC and the molecular embryology with a specific focus on the Hedgehog signalling pathway. A large amount of data from microscopic and molecular research consistently supports the hypothesis of a dysembryogenetic pathogenesis of BCC. Such evidence is promoting advances in the clinical management of this disease, with innovative targeted molecular therapies on an immune modulating basis being developed.

[Paramedian frontal clefts or superior orbital clefts]

Superior orbital frontal clefts are one of the rare craniofacial clefts described by Tessier in 1976, and occur most often sporadically. They are numbered 9, 10 and 11 in this classification, and are located respectively laterally, in the middle and medially to the upper part of the orbit. Their clinical expression is variable on soft tissue and bone, with possible dissociation of involvement. They range from a simple aesthetic defect to an eyes functional prognosis. CT scans are systematically required in this context. Their management must be adapted to the polymorphism of the damage, and is based on multidisciplinary approach. In case of ocular risk, the eyelid reconstruction is an emergency. In all other cases, treatment is deferred, but must be carried out at an early stage to ensure the child's healthy development.

Nonmelanoma Skin Cancers: Embryologically Relevant Sites and UV Exposure

Background:

Traditionally, nonmelanoma skin cancers (NMSCs) are considered mainly UV-related malignancies. Nevertheless, a strong correlation between the embryologically relevant sites (ERS) of the head and neck and the preferential sites of onset of basal cell carcinomas (BCCs) has long been supposed and demonstrated. The aim of this research was the investigation of the potential correlation between the ERS of the head and neck and the sites of tumor onset in all of the NMSCs.

Methods:

The distribution of 1165 NMSC was correlated with the ERS of the head and neck using the universally accepted anatomical diagrams featuring the congenital head and neck clefts and an original anatomical diagram showing the most credited sites of the embryonic fusion planes of the auricle.

Results:

In our sample, both BCC and SSC display an increased likelihood of onset in the ERS of the head and neck. A proportion of 93.10% BCCs was distributed within ERS, while 6.90% derived from non-embryologically relevant sites (P < 0.001). A proportion of 69.70% SCCs was distributed within ERS, while 30.30% derived from non-embryologically relevant sites (P < 0.001). The probability of tumors within ERS was significantly higher for BCC versus SCC (P < 0.001), with BCCs having a 5-fold increase in the probability of occurring in ERS compared to SCCs (P < 0.001).

Conclusions:

The ERS might host areas of cellular instability yielding to the development of an NMSC. The environmental UV exposure plays a relatively main role versus dysontogenic factors in the pathogenesis of SCC.

Sites of Basal cell carcinomas and head and neck congenital clefts: topographic correlation

Background:

The embryologic fusion planes might be related with the sites of onset of basal cell carcinoma (BCC), thus supporting an embryologic role for its pathogenesis.

Methods:

A study involving 495 patients with 627 BCCs of the head and neck was carried out over a period of 5 years by correlating the distribution of all BCCs with the sites of congenital clefts of the head and neck using (1) the original anatomic diagram of the Tessier classification of craniofacial clefts, (2) the anatomic diagram by Moore et al featuring the paths of the “hairline indicators” of craniofacial clefts that represent the cranial extensions of the Tessier classification, and (3) an anatomical diagram featuring the sites of congenital clefts of the neck.

Results:

The proportion of BCCs localized within a cleft site was significantly higher than those in the noncleft sites. The age of patients with BCCs localized within the Tessier cleft number 3 was the lowest among all cleft regions.

Conclusions:

A topographic correspondence between the sites of BCCs and the sites of congenital clefts was demonstrated in the head and neck. This evidence would support the hypothesis of an embryologic role for the pathogenesis of BCC. The existence of clusters of embryological stem cells in the sites of fusion and/or merging of embryonic processes might therefore be proposed. There may be special biology/physiology along these cleft lines that predispose BCC formation.

Pai syndrome: an adult patient with bifid nose and frontal hairline marker

OBJECTIVE

A 17-year-old previously unreported patient with Pai syndrome is described. The boy had median cleft of upper lip, a polypoid skin mass over the columella, a minimal cleft of the upper central incisors, frontal alopecia of the anterior hairline, and bifid nose. Magnetic resonance imaging showed pericallosal lipoma. No mental retardation was present, and a chromosomal study showed normal male 46, XY karyotype.

Asymmetry: molecular, biologic, embryopathic, and clinical perspectives

This overview of asymmetry addresses the following topics: chiral molecules; asymmetric signaling molecules, including N-cadherin, Shh, Fgf8, lefty1, lefty2, nodal, Pitx2, activin betaB, activin receptor IIA, and cSnR; situs abnormalities; asymmetric cell division; laterality in humans and animals; behavioral asymmetry in humans and animals; asymmetric embryopathies, including Tessier-type "clefts"; hemiasymmetries such as hemihyperplasia, hemihypoplasia, and hemiatrophy; asymmetric vascular syndromes, including Klippel-Trenaunay and Sturge-Weber syndromes; plagiocephaly of the synostotic and deformational types; somatic mosaicism, including a discussion of McCune-Albright syndrome, fibrous dysplasia, GNAS1 mutations, and Proteus syndrome.