Validity of clinic biopsy specimens in classifying histopathologic characteristics of recurrent nasopharyngeal carcinoma

Objective: To evaluate nasopharyngeal carcinoma resection specimens for heterogeneity of histologic patterns to determine if preoperative histologic characteristics of the clinic biopsy specimen are representative of the entire lesion. The null hypothesis is that clinic biopsy specimens are not necessarily representative. Design: Preoperative clinic biopsy specimens were measured to calculate their average size. Resection specimens were then sectioned and evaluated in increments corresponding to this size. Each of these increments was then histologically classified according to the World Health Organization (WHO) criteria. This classification of the preoperative biopsy specimens was compared with that of the resection specimen as a whole. Setting: University referral center. Patients: Twenty-six consecutive patients with recurrent nasopharyngeal carcinoma who underwent surgical resection. Radiation therapy failed in all patients. Main Outcome Measure: The presence or absence of WHO histologic heterogeneity in the nasopharyngectomy specimen was recorded. Disparity between preoperative clinic biopsy and resection specimens was recorded. Results: The mean clinic biopsy specimen size was 13.9 mm² or less than 1% of the available surface area of the nasopharynx. Of 26 resection specimens classified in 5 increments of this size, 15 (57.7%) were a single WHO type, and 11 (42.3%) were found to be mixtures of WHO types I, II, and III. Of 16 cases with preoperative biopsy specimens available, 4 (25%) were a different WHO classification than their corresponding resection specimen. Conclusions: Most clinic biopsy specimens were representative of their corresponding tumor resection specimens in their entirety; however, tumor heterogeneity is such that some biopsy specimens will not be representative. This finding may interfere with WHO classification data determined on the basis of clinic biopsy specimens and hence confound any meaningful data on treatment outcomes. It is recommended then that multiple nasopharyngeal biopsy specimens be obtained from disparate areas of the lesion and each subjected to independent histopathologic review.