The local spread of cancer of the facial skin appears to be markedly influenced by embryologic fusion planes as well as the surrounding facial structures. These fusion planes tend to set up individual areas in which cancer of the skin appears to spread rapidly, invading deeply before continuing its superficial spread that would cross a fusion plane. Soft tissue invasion of these neighboring regions may eventually lead to bone or nerve involvement, making tumor eradication much more difficult.

Five anatomical areas of the midface exist in which there is a rather constant reproducible type of spread of cancer. Cancers located over the supratip and columella tend to invade into the nose along the septum with the later site contributing to invasion of the superior aspect of the midlip and premaxilla. Lesions located along the lateral aspect of the nose tend to spread in a caudal-cephalic manner with through-and-through defects occurring along the nares. Cancers of the skin originating in the nasolabial fold tend to invade deeply toward the pyriform aperture and the nasal cavity before spreading on the cheek and lateral aspect of the upper lip. Cancers located in the glabella and root of the nose are prone to invade deeply and laterally toward the medial canthi. Cancers of the skin of the cheek tend to spread in a uniform nature from their central foci extending into the lower eyelid and upper lip while avoiding nasal involvement.

The columella appears to be a particularly high-risk site; cancers at this site have been described by many authors as a “potential time bomb.” Such tumors may extend directly along the septal cartilage, posteriorly into the nasal cavity, inferiorly into the maxilla, and superiorly into the anterior skull base, meaning that recurrence is often detected late and is extremely difficult to treat. In addition to that, it is the region of the nose most prone to develop lymph node metastases (Fig. 21.2A and B).

The nasal vestibule is studied separately from other sites of the nose, because it is considered part of the nasal cavity. Carcinomas restricted to the nasal cavity are uncommon accounting for only 20% of all cancers arising in the paranasal sinuses and nasal cavity. The nasal vestibule is also considered the subsite in the nasal cavity that is least often affected by cancer, with most cancers arising from the turbinates. Other subsites affected in descending order of frequency are the nasal septum and floor of the nose. Carcinomas of the vestibule are usually of low histologic grade and demonstrate a relatively low metastatic potential. Lymphatic spread, when occurs, does to the facial and parotid lymph nodes first, before they reach levels I and II. Only 40% of the patients with positive nodes ultimately survive.