CT and MRI diagnosis of tumor originating in the pterygopalatine fossa

Objective: To investigate the CT and MRI findings of tumors originating in the pterygopalatine fossa so as to promote the diagnostic accuracy. Methods: All 11 patients with tumors arising from the pterygopalatine fossa were confirmed by pathology and surgery. CT and MRI appearances were analyzed retrospectively. Results: The tumors included 3 neurilemmomas, 2 neurofibromas, 3 angiofibromas, 2 adenoid cystic carcinomas, and 1 melanoma, and they all extended through communicating pathways of the pterygopalatine fossa. On HRCT, neurogenic tumors caused enlargement of the pterygopalatine fossa with thinning of their bony walls, while MRI demonstrated isointense signal to brain on T1WI and hyperintense signal on T2WI. Two neurofibromas showed homogeneous enhancement after administration of contrast medium while 3 neurilemmomas showed heterogeneous enhancement. On HRCT scans, angiofibroma caused enlargement of the pterygopalatine fossa, eroding their bony walls. On MR imaging, the lesions were isointense compared to muscle on T1WI, hyperintense on T2WI with marked postcontrast enhancement. One case of angiofibroma showed scattered stippling or stria-shaped signal voids and inhomogeneous postcontrast enhancement. On CT scans, adenoid cystic carcinoma revealed moth-eaten bony wall of the pterygopalatine fossa with poorly defined margins and irregular shapes. Adenoid cystic carcinoma showed hypointense signal compared to muscle on T1WI, inhomogeneous hyperintense signal on T2WI and heterogeneous postcontrast enhancement. One case of melanoma showed enlargement of pterygopalatine fossa and destruction of the bony walls except for the anterior wall by invading adjacent structures with well-defined border and irregular shape. On MR imaging, the lesion showed isointense signal compared to muscle on T1WI and hyperintense signal on T2WI with discrete mottled or linear signal voids and inhomogeneous postcontrast enhancement. Conclusion: HRCT can depict bony changes clearly and MRI can demonstrate optimally the extent of the lesion in pterygopalatine fossa. Both imaging modalities can contribute to the diagnosis of neurogenic tumor and angiofibroma and can provide information for therapeutic procedure and surgical planning