VALIDITY OF CLINIC BIOPSY SPECIMENS IN CLASSIFYING HISTOPATHOLOGIC CHARACTERISTICS OF RECURRENT NASOPHARYNGEAL CARCINOMA

Objective: To evaluate nasopharyngeal carcinoma resection specimens fo r heterogeneity of histologic patterns to determine if preoperative hi stologic characteristics of the clinic biopsy specimen are representat ive of the entire lesion. The null hypothesis is that clinic biopsy sp ecimens are not necessarily representative. Design: Preoperative clini c biopsy specimens were measured to calculate their average size. Rese ction specimens were then sectioned and evaluated in increments corres ponding 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 r eferral center. Patients: Twenty-six consecutive patients with recurre nt nasopharyngeal carcinoma who underwent surgical resection. Radiatio n therapy failed in all patients. Main Outcome Measure: The presence o r absence. of WHO histologic heterogeneity in the nasopharyngectomy sp ecimen was recorded. Disparity between preoperative clinic biopsy and resection specimens was recorded. Results: The mean clinic biopsy spec imen size was 13.9 mm(2) or less than 1% of the available surface area of the mm nasopharynx. Of 26 resection specimens classified in 5 incr ements 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 wi th preoperative biopsy specimens available, 4 (25%) were a different W HO classification than their corresponding resection specimen. Conclus ions: Most clinic biopsy specimens were representative of their corres ponding tumor resection specimens in their entirety; however, tumor he terogeneity is such that some biopsy specimens will not be representat ive. This finding may interfere with WHO classification data determine d on the basis of clinic biopsy specimens and hence confound any meani ngful data on treatment outcomes. It is recommended then that multiple nasopharyngeal biopsy specimens be obtained from disparate areas of t he lesion and each subjected to independent histopathologic review.