Malignant tumors of the sphenoid sinus are clinically rare. According to Godtfiedson's (1947) analysis of 218 cases of paranasal sinus malignancies, the maxillary sinus was the most common site, accounting for 86.7%, followed by the ethmoid sinus at 43.6%, and the sphenoid sinus at 2.3%. Sphenoid sinus malignancies are divided into primary and secondary types. Secondary malignancies originating from distant organ metastases include prostate cancer, myeloma, stony goiter (thyroid carcinoma), stony goiter (thyroid carcinoma), lung cancer, liver cancer, breast cancer, kidney cancer, and others. Tumors invading from adjacent organs mainly include those from the nasal cavity, nasopharynx, and sellar region. Barrs (1974) suggested that metastatic tumors in the sphenoid sinus more frequently originate from distant metastases than from adjacent organ involvement.

bubble_chart Pathological Changes

According to Alexander (1963), primary malignant tumors of the sphenoid sinus include squamous cell carcinoma, lymphoepithelial carcinoma, undifferentiated carcinoma, cylindric cell carcinoma, adenocarcinoma, giant cell tumor, ameloblastoma, and malignant inverted papilloma. Due to the thin bony walls of the sphenoid sinus, which are easily destroyed by tumors, the earliest symptoms and signs are caused by invasion of adjacent organs. Metastatic carcinomas progress more rapidly than primary carcinomas in terms of destruction. Clinically, cervical lymph node metastases are rarely observed. Wyllie (1973) reported that among 6 cases of sphenoid sinus tumors, only 2 showed cervical lymph node metastasis.

bubble_chart Clinical Manifestations

Malignant tumors of the sphenoid sinus mostly occur in adulthood, with no gender difference. Primary malignant tumors of the sphenoid sinus may present with progressive headache as the tumor enlarges and compresses nerves. The headache is often located deep in the orbit or behind the eyeball, deep in the neck or the frontal-parietal region, sometimes in the occipital area and spreading to the back of the neck. In some cases, the headache is not prominent, which is most prone to misdiagnosis. If the tumor extends to the lateral wall, the first symptom is abducens nerve palsy, leading to inward deviation of the eyeball and diplopia. Subsequently, the trochlear and oculomotor nerves may also become paralyzed, clinically manifesting as fixed eyeball, drooping of the upper eyelid (blepharoptosis), and dilated pupils. Compression of the optic nerve may result in decreased vision or blindness. Ocular symptoms may gradually progress from unilateral to bilateral and are often accompanied by exophthalmos. If the sella turcica is invaded, symptoms of hypopituitarism may appear. It can also manifest as diabetes insipidus. In addition to the above symptoms and signs, metastatic carcinoma of the sphenoid sinus often reveals symptoms and signs of distant primary cancer during systemic physical examination. Therefore, clinicians should pay special attention to conducting a comprehensive systemic examination for space-occupying lesions of the sphenoid sinus to avoid misdiagnosis caused by focusing solely on local symptoms.

Due to their low incidence, concealed anatomical location, and inconspicuous early symptoms, malignant tumors of the sphenoid sinus are prone to misdiagnosis. Therefore, for patients presenting with deep headaches followed by cranial nerve palsies (VI, IV, III, V), sphenoid sinus diseases should be considered first. If these symptoms progress rapidly, malignant tumors of the sphenoid sinus should be suspected. In such cases, a comprehensive examination of the patient is necessary, including evaluations of systemic organs, the nasal cavity, nasopharynx, ophthalmology, and neurology. More importantly, imaging studies such as anteroposterior and lateral skull X-rays, skull base X-rays, optic nerve X-rays, carotid angiography, head CT, or MRI should be performed to determine the tumor size and extent of spread. Diagnosis of sphenoid sinus tumors requires pathological examination of biopsy specimens obtained via puncture or transseptal sphenoidotomy. This condition must be differentiated from nasopharyngeal carcinoma, sphenoid sinus mucocele, and intrasellar or parasellar tumors.

bubble_chart Treatment Measures

Malignant tumors of the sphenoid sinus have a poor prognosis despite comprehensive treatment, particularly in cases with distant organ metastasis or cervical lymph node involvement. For primary tumors, the sphenoid sinus can be opened and the tumor resected via the nasal septum. However, caution must be taken during surgery to avoid rupture of the carotid artery due to tumor erosion of the lateral bony wall and subsequent adhesion to the tumor. Blindly grasping the tumor can easily lead to fatal hemorrhage from carotid artery rupture. To prevent this, the tumor should be resected in stages under microscopic guidance. If significant pulsation and adhesion to the tumor are observed, forceful removal should be avoided. The residual tumor can then be treated with supplementary radiotherapy, which can still yield satisfactory results. Van Wart treated 7 cases with cobalt-60, including one undifferentiated carcinoma patient who survived for 5 years. The radiation dose was 45–55 Gy, repeated four times within one year. The remaining cases died within six months to two years.