Comparison between cytologic processing upper urinary tract microbiopsies and conventional processing of surgical biopsies in diagnosing upper tract urothelial carcinoma (UTUC)
Taylor Harris, B.S., Zhenwei Zhang, MD,PhD, MaryPat Scott, BA, Andrew Fischer, MD, Jennifer Yates, MD.
University of Massachusetts, Worcester, MA, USA.
Introduction We previously reported that cytologic processing of microbiopsies showed superior sensitivity for detecting high grade urothelial carcinoma (HGUC), compared with conventional processing. In this independent and larger cohort, we further evaluated the efficacy of cytologic processing of microbiopsies. Materials and methods We reviewed the pathology database at a single institution for upper tract microbiopsies in which both surgical pathology and cytology processing were conducted concurrently from the same site. We excluded microbiopsies taken for non-urothelial diagnoses. Thirty-four patients had 64 paired microbiopsies. All microbiopsy specimens were collected from upper urinary tract including the ureter, renal pelvis and calyx using the Piranha 3F flexible ureteroscopic biopsy forceps. The same number of microbiopsies were taken for cytology and surgical pathology. The biopsy forceps was swirled in the cytorich red or formalin, and cleaned by swirling in normal saline between each biopsy. Holmium laser was used for hemostasis after both biopsies were complete if necessary. Cytologic processing involves making a cellblock from the visible fragments in the vial by pipetting directly to a Cellient cell block cassette. The rest of the supernatant is prepared into a ThinPrep for cytologic diagnosis. Surgical processing involves filtering the specimen through histology lens paper, folding the paper, processing in a standard tissue processor, and embedding the fragments in paraffin manually. McNemar's test was performed with Python and its Scipy package to compare the processing methods. Results When combined with both methods, 45 cases (70%) were diagnosed with urothelial carcinoma, whereas 41 (64%) cytologic specimens and 32 (50%) on the paired surgical biopsies were found to have urothelial carcinoma respectively. There was a statistically significant difference in diagnosing UTUC (p = 0.039). Cytologically processed microbiopsies had a sensitivity of 91%, while conventional processing has a sensitivity of 71%. 20 cases in this cohort were definitively diagnosed as high grade urothelial carcinoma by either method. 19 of these were diagnosed by cytological processing (95% sensitivity), and 8 were diagnosed by surgical processing (40% sensitivity). There was a statistically significant difference in diagnosing HGUC (p = 0.002). Furthermore, surgical processing resulted in 4 (6.25%) non-diagnostic samples with no tissue present for pathologic evaluation; Cytological processing resulted in only 2 (3.13%). Surgically processed biopsies resulted in 10 (15.6%) additional samples which were identified as being too scant of tissue, lacking in cells, or too denuded for adequate analysis and diagnosis.
Conclusions Cytologic processing of upper urinary tract microbiopsies had a greatly improved efficacy in diagnosing Urothelial Carcinoma, particularly HGUC, as compared with the conventional surgical biopsy method. Improved sensitivity is likely related to the complete recovery of desquamated cells in the cytologic ThinPrep slide. Cytologically processed microbiopsies can add diagnostic information and guide clinical management. In light of these results, we strongly encourage the use of cytologically processed microbiopsies together with standard surgical biopsies.
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