Surgical pathology of the skull base: A 7-year experience

A significant diversity of tissue types interface at the base of the skull and contribute to the diagnostic challenges of skull base surgical patholog y. Advances in surgical technique now permit biopsy and resection of lesion s previously termed "inoperable.": Retrospective review was made of all pat hology specimens from skull base surgeries performed at the University of C alifornia Davis Medical Center from 1990 to 1996. Surgical biopsies and res ections were performed on 186 patients who had 33 distinctive diagnoses. An y preoperative biopsy or tissue from referring institutions was reviewed pr ior to skull base surgery. One hundred eighteen patients had benign lesions , the most frequent of which were pituitary adenoma (55) and acoustic neuro ma (27). Other benign lesions included angiofibroma, meningioma, fibrous dy splasia, and paraganglioma. Sixty-eight patients had malignant tumors, 32 o f which were squamous cell carcinoma. Other malignancies included salivary carcinomas, basal cell carcinoma, neuroblastoma, melanoma, and several sarc omas. Unexpected findings were two metastatic carcinomas and five inflammat ory lesions. Nearly 1500 intraoperative consultations were pel formed to es tablish resection margins and less commonly to confirm the diagnosis. The d iscrepancy rate between the intraoperative and final diagnosis was 1.8%. Im munohistochemistry and/or electron microscopy was utilized in 44% of the sp ecimens to confirm the diagnosis. Surgical pathology is an essential ingred ient to a successful skull base surgery program. Pathologists are involved in both pre and intraoperative decisions. The diversity of lesions that ari se from the skull base often has overlapping histologies that require caref ul attention to morphology and the use of ancillary studies For accurate di agnosis. The need for frequent intraoperative interpretations contributes t o the significant challenge for the surgical pathologist.