Perineural tumor spread from a palatal carcinoma. (Imaging Clinic).

Carcinomas of the hard or soft palate are known to spread perineurally along the palatine branches of the second division of the trigeminal nerve (V2). Perineural extension of malignant head and neck tumors is a well-known phenomenon. (1) Squamous cell carcinomas of cutaneous or mucosal origin, particularly adenoid cystic carcinomas of major or minor salivary origin, are the most common primary neoplastic processes to spread perineurally, as was seen in the case described here. The presence of perineural tumor spread has considerable implications for prognosis and treatment.

Our patient was a 62-year-old woman who complained of swelling on the roof of her mouth. She exhibited no evidence of trismus, nasal obstruction, loss of facial sensation, or difficulty with mastication. Examination of the oral cavity revealed the presence of a firm, nontender, 2 x 2-cm mass in the right hard palate. The mass extended toward the midline and the soft palate adjacent to the posterior maxillary teeth. All cranial nerves were intact.

Biopsy analysis of the lesion identified an adenoid cystic carcinoma. Computed tomography (CT) and magnetic resonance imaging (MRI) were performed prior to the excision of the lesion. There was a localized widening of the pterygopalatine fossa. MRI demonstrated a primary soft-tissue mass in the soft-tissue palate (figure 1) and a localized abnormal intensity on enhancement in the region of the pterygopalatine fossa (figures 2 and 3). These findings indicated a perineural spread from the palatal carcinoma.

Adenoid cystic carcinoma is an uncommon malignancy that originates in salivary gland tissue. This tumor is well known to have a high incidence of perineural spread. When perineural spread occurs, a significant decrease in survival has been demonstrated. (2)

Symptoms of perineural spread from the palate include facial pain, paresthesias, and other neuropathies related to branches of V2. Intraorbital tumor involvement can occur as a result of extension to the inferior orbital fissure. Antegrade spread along V2 or V3 can result in neuropathy of those nerves and involvement of the cavernous sinus and might lead to multiple cranial nerve involvement. MRI is proving to be the method of choice when perineural spread of the tumor is suspected. (3)

From the Department of Otorhinolaryngology (Dr. Mueller and Dr. Friedlander) and the Department of Radiology (Dr. Palacios), Louisiana State University Health Sciences Center, New Orleans.

References

(1.) Ginsberg LE, DeMonte F. Imaging of perineural tumor spread from palatal carcinoma. AJNR Am J Neuroradiol 1998;19:1417-22.

(2.) Fordice J, Kershaw C, El-Naggar A, Goepfert H. Adenoid cystic carcinoma of the head and neck: Predictors of morbidity and mortality. Arch Otolaryngol Head Neck Surg 1999;125:149-52.

(3.) Curtin HD, Williams R, Johnson J. CT of perineural tumor extension: Pterygopalatine fossa. AJR Am J Roentgenol 1985;144:163-9.