Prostate Biopsy Processing

An Innovative Model for Reducing Cost, Decreasing Test Time, and Improving Diagnostic Material

Paari Murugan, MD; Dip Shukla; Jennifer Morocho, HTL; Deanne Smith, PA; Drew Sciacca, PA; Meghan Pickard, PA; Michelle Wahlsten, HTL; Ashley Gunderson, HTL; Badrinath Konety, MD; Mahmoud A. Khalifa, MD; Christopher Warlick, MD

Disclosures

Am J Clin Pathol. 2019;152(6):757-765. 

In This Article

Materials and Methods

In this prospectively designed single-institution study, 48 consecutive prostate specimens were subject to the experimental protocol. Institutional review board approval was obtained as per institutional requirement. An 18-gauge prostate biopsy gun (Bard Medical Max Core; Bard Medical) employed in routine urologic practice at our institution was used to obtain two sets of sextant biopsy specimens ex vivo from 30 prostatectomies performed for prostate carcinoma, eight cystoprostatectomies performed for bladder carcinoma, and 10 prostate specimens obtained from autopsy cases in patients who died of unrelated causes. For each specimen, a pair of biopsy specimens was obtained at near-identical locations (<1 mm apart) from bilateral base, middle, and apex portions of the gland to duplicate physical and morphologic similarity. One set was processed in accordance with the standard protocol (SP) employed in our institution, and the other was processed using a multiplex chip (MC) protocol (MCP). In the SP, each tissue core was swiped onto a moist filter paper and fixed in separate site-designated formalin containers. These were routinely grossed by forceps extraction, examined, described, and placed between sponges into separate tissue cassettes. After the standard tissue-processing steps for dehydration, clearing, and paraffin infiltration, the cores were embedded in molten paraffin using forceps to create six tissue blocks. These were then microtome sectioned at three levels, placed on separate slides, H&E stained, and cover-slipped for microscopic examination. The second set of biopsy specimens was processed using the MCP. The multiplex BxChip (Lumea), costing $12, is a sectionable 22-mm-long proprietary biomimetic matrix with six 0.8-mm-wide grooves separated by three differently colored partition ridges. The MC is preplaced between formalin soaked sponges in a standard tissue cassette. The six biopsy cores were directly transferred from the needle into the site-designated (by color codes) MC grooves via capillary action and gentle in-axis rotation Figure 1. The cassette was placed in a formalin container after which gross examination and description were performed by examining the tissue in the MC in situ. The single cassette containing the six biopsy cores was then subject to routine tissue processing. Embedding was performed by placing the MC as a whole in molten paraffin without tissue handling. The MC, along with the tissue cores, was sectioned at three levels and placed on three separate slides, H&E stained, and cover-slipped for microscopic examination Figure 2.

Figure 1.

A, Multiplex chip (BxChip): a 22-mm × 14-mm sectionable biomimetic matrix with 0.8-mm-wide grooves separated by color-coded partition ridges that can be custom designated by biopsy location. The chip is placed in a standard tissue cassette, supported by sponges. LA, left apex; LB, left base; LM, left mid; RA, right apex; RB, right base; RM, right mid. B, Direct loading of the biopsy core from needle tip into the designated matrix groove by capillary action.

Figure 2.

Study methodology depicting major processing steps, quantity of material involved, and key analytical parameters.

Outcome measures included mean processing time (grossing, embedding, sectioning), sample quality (tissue fragmentation, total tissue length, total cancer length), reading time, and cost. Fragmentation was measured as linear vs nonlinear. Linear fragmentation was defined as a more than 2-mm in-line separation of the core fragments. Nonlinear fragmentation was defined as a more than 2-mm out-of-line/plane separation of the core fragments that typically causes considerable challenge in ascertaining which core the fragments belong to. The microscopic examination was performed on both the standard and MC material by an expert genitourinary pathologist (P.M.). The reading time involved routine examination of all levels of the biopsy tissue and, where applicable, cancer quantification by length, percentage core involvement, and Gleason scoring.

A comparative cost analysis of prostate biopsy specimens processed by the two protocols was conducted, and a per-case cost estimate was calculated. This included the cost of materials (MC, formalin containers, tissue cassettes, slides, etc), pathologist assistant/histology technician time, and pathologist time. A two-tailed paired t test was used for statistical analysis of the various process metrics, with significance marked by a P value of less than .05.

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