Carcinoid tumors occur most commonly in the colon, rectum, and cecum, and are derived from the enterochromaffin cells of gastrointestinal and bronchopulmonary systems (
3). Carcinoid tumors rarely develop in the head and neck, especially in the sinonasal area, as primary tumors. Furthermore, typical carcinoid tumors arising in the sphenoid sinus are extremely rare, and the present case is unique in that it presented as an aggressive typical carcinoid tumor involving the right nasal cavity, sphenoid bone, clivus, and occipital condyle.
The clinical features of this tumor were nonspecific and similar to those of other sinonasal tumors. Common presentations include epistaxis, nasal obstruction, exophthalmos, nasal pain, and headache (
4). Although a typical carcinoid tumor is usually non-functional, it may cause the carcinoid syndrome ( 4). Flushing, diarrhea, and cardiac involvement are typical symptoms of the classic carcinoid triad ( 5). However, carcinoid syndrome occurs only in about 10% of patients with carcinoid tumors ( 5). In this case, the patient did not have any other symptoms of carcinoid syndrome.
Diagnosis is based on the characteristics of the carcinoid tumor on histopathological and immunohistochemical analyses for chromogranin A, synaptophysin, neuron specific enolase, CD56, and cytokeratins (
4). Typical carcinoid tumors are well-differentiated lesions and are distinguished from moderately differentiated atypical carcinoid tumors by the absence of mitoses, pleomorphism, and necrosis ( 6). Typical carcinoids are less aggressive and are managed differently, making an accurate diagnosis is critical.
An optimal treatment method for typical carcinoid tumors of the paranasal sinuses has not been established because these lesions are very rare. Treatment is based on the location of the primary tumor and guided by whether metastasis has occurred. Although complete surgical resection has been the most successful treatment, radiotherapy and chemotherapy should be performed as postoperative adjuvant therapy when complete resection is difficult and surgery is ineffective (
2). In the present case, total surgical resection of the typical carcinoid tumor of the sphenoid sinus was difficult because the tumor had invaded the sphenoid bone, clivus, and cavernous sinus. However, this tumor was a well-differentiated and low grade malignancy without involvement of neck nodes and distant sites, which was successfully treated by endoscopic transseptal transsphenoidal surgery and IMRT.
Although aggressive and destructive behavior of a typical carcinoid tumor is very rare, it is important to consider this disease entity in the differential diagnosis of sinonasal tumor. When it appears impossible to completely resect a locally aggressive typical carcinoid tumor in the sphenoid sinus, radiotherapy could be considered as postoperative adjuvant therapy.