Congenital midline upper lip sinuses with intracranial extension - A variant of nasal dermoid? An embryology-based concept.

OBJECTIVE

The study aimed to present the comparative analysis of midline congenital upper lip sinuses (MCULS) and nasal dermoids (NDs). The clinical similarity of congenital midline pathologies of the midface was interesting subject for further studies. Therefore, histopathological, and embryological background were also analyzed to verify a hypothesis that NDs and MCULSs are the different variants of the same entity.

MATERIAL AND METHODS

The study group included 27 surgically treated pediatric cases with the congenital midline sinus of the nose (n = 25) or upper lip (n = 2). Seven children presented intraoperatively confirmed intracranial extension of the abnormality, 6 in NDs group and 1 in MCULS group. Apart from clinical characteristics also histopathological results were compared in both groups. An analysis of the literature concerning the proposed theories of origin of NDs as well as the current classification systems of MCULSs and NDs were conducted.

RESULTS

The analysis revealed that MCULSs present the same clinical characteristics as NDs. No differences were noticed in the histopathological results. The embryological theories presented so far are insufficient to convincingly explain the precise process of origin of abnormalities such as ND and MCULS. Nevertheless, the developmental embryological processes of the midface shed a new light on the common origin of NDs and MCULSs. The proposal of an update of the existing classification of midline congenital midface sinuses was presented.

CONCLUSIONS

The comparative analysis of clinical, histopathological, and embryological characteristics confirms that NDs and MCULSs are different forms of the same entity. Embryological implications result in the possibility of intracranial extension in each case of MCULS. Therefore, CT and MR imaging which provide irreplaceable information are recommended for all patients with MCULS. The updated classification of midline congenital midface sinuses should be taken into consideration.