Both magnetic resonance imaging (MRI) and computed tomography (CT) scan are useful in the diagnosis and management of these neoplasms when orbital invasion occurs. MRI is considered the imaging modality of choice for soft tissue definition and CT scan is best for revealing the location and extent of bone destruction, which is invariably present. The lesions are usually homogeneous, highly attenuated in character, and enhance to some degree (see Fig. 16.3). Physicians working in this field for long have been hopeful these imaging modes would be helpful in determining the presence and degree of perineural spread.
Nemzek et al. (1998) reported a sensitivity of 95% for MRI detection of perineural spread but only a 63% sensitivity for mapping the entire extent of the process. Contrarily, despite a clinical suspicion of perineural spread, de Keizer et al. (1997) did not find either imaging method helpful in determining nerve extension. Preoperative detection of insidious but not clinically visible perineural spread is almost always a component of secondary orbital squamous cell carcinoma. The image display of perineural spread is an enlarged or expanded cord-like structure extending outward from the periphery of the mass lesion (Veness and Biankin, 2000), as it may be a solitary structure appearing on an image plane beyond the carcinomatous mass.

In a small zone around the anterior nares, squamous epithelium is normally arranged in a pavement-like pattern similar to that of skin. Elsewhere in the upper respiratory passages, squamous epithelium has undergone functional modification into a pseudostratified, sometimes ciliated, epithelium. The histologic pattern of this epithelium is, however, alike everywhere, but it varies according to the functional purposes of the specific anatomic sites. In the mucous membranes of the sinuses and anterior nasal cavity, the epithelium is ciliated and less stratified than in skin but it still possesses some characteristics of keratinization of skin. In the more posterior recesses of the nasal cavity, the epithelium becomes more columnar with little or no keratinization. This histologic pattern is frequently referred to as a transitional type of epithelium. In the nasopharynx, the epithelium becomes but a loose and thin layer of squamous cells covering a predominantly lymphocytic-adenoid type of stroma. Such an arrangement is usually termed a lympho-epithelial type of respiratory epithelium. Lower down the respiratory passages, squamous cell surfaces show further changes that make possible their identification with a specific anatomic area when tissue specimens are examined microscopically. The carcinomas, in their growth, reflect these nuances in cellular morphology, but basically, all of them represent malignant squamous metaplasia.

Squamous cell carcinomas of the maxillary sinus and nasal passages vary significantly in the degree of cellular differentiation. In general, the poorly differentiated and anaplastic types are more common than the highly keratinizing types (see Fig. 16.4). As the neoplasm becomes more anaplastic, the prickle type cell may take on a spindle shape in some of the higher-grade malignancies. The latter cellular patterns resemble the histologic picture of some sarcomas. The cellular boundaries of these proliferating cells also become less distinct, and mitosis and hyperchromatism are observed, as with all malignancies. Foci of degeneration may appear in the highly undifferentiated tumors, giving them a pseudoglandular appearance.

It might be expected that the more malignant types of squamous cell carcinomas would be the ones that would finally reach the orbit. Among the cases in the Mayo Clinic Series, this was not always so with those tumors from the nasal cavity. Of the 52 carcinomas originating in the maxillary antrum, the malignancy was, in all the 52, either
grade 3 or 4. Of the squamous cell carcinomas arising in the nasal cavity, there was a nearly equal distribution among grade 2, grade 3, and grade 4 anaplastic types.

The histopathologic features of the secondary neoplasms arising in the skin of the face, eyelids, temple, and eyebrow were similar to those of squamous cell carcinomas elsewhere in the integument (see Fig. 16.5). They were more differentiated tumors and their course was more prolonged than other carcinomas, and only one case had malignancy of grade 4 degree.

The behavior of squamous cell carcinomas with secondary orbital extension is notable for their perversive spread, their refractory response to irradiation, and their high recurrence rate, even with what is considered a major surgical ablation of both soft tissue tumor and the bone involved. In general, prognosis has been related to the degree of malignancy; the more undifferentiated the tumor, the worse the prognosis. These carcinomas possess potentialities for local invasive growth as well as distant metastatic spread. In many tumors of grade 4 showing a malignant degree of undifferentiation, the prognosis is almost hopeless. Prognosis is also influenced to a lesser extent by other factors. With secondary carcinomas arising from the maxillary antrum, for example, the eventual outcome may be influenced by their size and extent at the time of discovery. Some of these carcinomas are not discovered until they have invaded the orbit and by this time they will be almost beyond the boundaries of a radical dissection. For those carcinomas that invade the orbit from adjacent integumentary structures, prognosis may be altered by the completeness of the initial surgical treatment; once the tumor has recurred owing to incomplete excision, the opportunity to eradicate the tumor by subsequent treatment is proportionately limited.

In the several disorders we have dealt with of this vicious neoplasm, the goal of successful treatment—and possible cure—has been the total surgical eradication of the tumor. With recurrence of the neoplasm, it was evident that incomplete excision was the rule. The culprit in this fallacy probably has been the insidious, unsuspected, extension of the carcinoma by perineural spread (see Fig. 16.6). Even present refinements in imaging methods cannot always detect this spread.

In the 1940s and 1950s, we advised exenteration of the orbit in people showing early stage, orbital invasion. This, sometimes, was considered too harsh. However, later, recurrent tumor would be surgically discovered in the former epicenter of the lesion along the side away from the orbit. A somewhat similar situation evolved when Mohs surgery, several decades ago, became popular for lesions around the face and periorbital adnexae. When a lesion was removed and the margins were negative for carcinoma cells, it was assumed that a complete excision had been performed. Alas! This technique was not infallible. Recurrences were later related to skip foci of cells along the nerve.

In our 50-year tumor survey (see Table 3.3), there are 52 secondary basal cell carcinomas (2.9% of the total 1,795 orbital tumors and 7% of the total 735 secondary orbital tumors). The primary sites of these neoplasms are listed in Table 16.3. Eighty-six percent (45/52) of our patients had recurrent tumor at the time of initial presentation. Often, the duration of symptoms was so long or multiple surgical procedures so numerous that the patients forgot such data. The mean age at the time of presentation was 64 years
(range 28 to 88 years). The male-to-female ratio was 34:18. The right orbit was affected in 31 patients, the left orbit in 19 patients, and 2 patients had bilateral orbital disease.

This type of neoplasm is a master of disguise. In the early stages of growth, the tumor may be a round, elevated, smooth nodule with a shiny surface. In the upper eyelid and eyebrow, it may be warty. Or it may be a sinuous, elongated, superficial, or a lumpy ulceration along the margin of the lower eyelid. Sometimes the tumor is elevated and nodular but with a scaly center surrounded by a rolled border. Lastly, the tumor may be nothing more than an innocent-looking indurated plaque.

However, by the time orbital invasion occurs, these singular aspects tend to merge into an ugly, dirty-looking ulcer with an elevated irregular edge that is covered by a smelly crusted exudate. The surrounding tissues become progressively indurated as the lesion penetrates deeper into the soft tissue. Very advanced lesions may bleed easily, undergo partial necrosis, or show a fistula between the orbital cavity and nose.

The clue to orbital invasion is a fixation of the ulcerated lesion to the underlying rim or surface of the bony orbit. At this stage, the surrounding soft tissues usually show a mild inflammatory response characterized by redness and swelling of tissues or chemosis of adjacent conjunctiva. Pain is not a common accompaniment of early orbital invasion. Only 2 of our 40 cases noted pain at the time of presentation.

Gradually, the tumor becomes rooted to the orbicularis oculi muscle of both the upper and the lower eyelids, the canthal tendons, and the extraocular muscle nearest to the advancing border of the lesion. This results in fixation and immobility of the eyelids and a tethering effect on ocular motility (see Fig. 16.7). Later, the eye becomes immobile and “frozen,” corneal desiccation and perforation occurs, and the vision is lost. Seven of our patients had a visual acuity of hand movements or less in the affected eye at the time of presentation.

Once the neoplasm gains access to the periorbita and soft tissues of the orbital cavity, it tends to expand in a circular fashion in preference to a deeper penetration. Eradication may be possible at this stage provided there is no bone involvement.

The most common areas of early orbital extension, by this neoplasm, are the medial and lateral canthi. A CT scan will show the posterior extent of the soft tissue mass along the inner face of the medial or lateral wall of the orbit, and there may be no bone destruction (see Figs. 16.8 and 16.9). Even so, upon palpation, the anterior orbital rim may have some irregularity indicating minimal bone involvement at this stage. Neuro-imaging is of critical importance in revealing the posterior extent of a recurrent neoplasm that has deeper involvement of orbital tissue. Bone destruction, if present, will also be evident by CT scan. T₁ contrast–enhanced, fat-suppressed MRI will show the makeup of the mass and enhancement of the dura if early intracranial expansion is present (Selva et al., 2003).