Teaching Case

Hoarseness and cough in a 39 year old male patient (heavy smoker).

Hoarseness and cough in a 39 year old male patient, heavy smoker (20 cigarettes/day for 20 years). MR neck after ENT consultation.

The nasopharynx is in direct communication with the middle ear cavity via eustachian tubes. In adults, squamous cell carcinoma (SCCA) accounts for 70% of the malignacies arising in the nasopaharynx. Other tumors of this region include lymphoma (20% of cases), while the remaining 10% are due to a variety of lesions including adenocarcinoma, cystic adenoma, rhabdomyosarcoma, melanoma etc. SCCA has a high incidence in Asia, being the most common tumor in males and the third most common in cancer. Its incidence is higher in the sixth decade of life. Several factors have been associated with this tumor, including the presence of antibodies against EBV and environmental tumors. The most common used classification is the one devised by the World Health Organization and histopathology, which divides these tumors into three types: squamous cell carcinoma (type 1), nonkeratinizing carcinoma (type 2), and undifferentiated carcinoma (type 3). The clinical presentation depends on the localization, with small lesions being asymptomatic. The most common presenting complaint is jugular or spinal accessory lymphoadenopathy. The effective volume of the tumor and the entity of the local dissemination represent critical parameters in predicting the probability of control of the tumor with radiotherapy. Specific objectives of the MR examination consist in identifying the tumor extension beyond the pharyngo-basilar fascia, in the parapharyngeal and masticator spaces, the infiltration of the cranial base and the perineural/perivascular dissemination. In specifying the entity of the tumor volume the SE sequences are more accurate than CT because they discriminate better between the tumor and the muscular walls of the pharynx and prevertebral muscles. MRI demonstrates in optimal way the neoplasm extension of through the pharyngobasilar fascia, in the posterior direction, towards the prevertebral muscles and the clivus. Since MRI identifies more easily the tensor veli palatini muscle, it can stage with greater precision the extension to the retrostyloid compartment (tumor confined to the muscle) and the prestyloid compartment (tumor extended beyond the muscle). In the carcinoma of the rhinopharynx, the invasion of the pterigo-palatine fossa and the masticator space constitutes a relatively infrequent and late event. The invasion is demonstrated with the substitution of the adiposo tissue of the pterigo-palatine fossa with tumoral tissue. In approximately 60% of the cases with bony erosion (pterygoid plates, wall of the maxillary sinus) the lesion extends also to the infratemporal fossa and/or the inferior orbital fissure. The differential diagnosis of a tumor mass originating in the rinopharynx comprises benign tumors: juvenile angiofibroma and polyps, and malignant tumors: in the first place carcinoma of the rinopharynx, lymphoma, rhabdomyosarcoma, plasmocytoma, chordoma and metastasis. External beam supervoltage irradiation represents the standard treatment of nasopharyngeal carcinoma while brachytherapy may be beneficial in selected patients. Surgery has a limited role in the treatment of nasopharyngeal carcinoma because it is very often difficult to obtain adequate surgical margins of the tumor mass. Neck dissection is usually performed to control the disease if neck disease is still present or recurs after radiotherapy. However, the global prognosis depends on other factors that include size of primary lesion, extent of disease, duration and extent of symptoms, the presence of skull base erosion, and nodal involvement at multiple levels. Neoplastic disease of the nasopharynx and the parapharyngeal space requires thorough assessment of location and extent in order to plan appropriate treatment. CT allows the deep soft tissue planes to be evaluated and provides a complement to the physical examination. It is especially helpful in regions involving thin bony structures (paranasal sinuses, orbita). MRI possesses many advantages over other imaging modalities caused by its excellent tissue contrast. In evaluating regions involving predominantly soft tissue structures (nasopharynx and parapharyngeal space) MRI is superior to CT.