A comparison of microscopic ink characteristics of 35 commercially available surgical margin inks

Application of dyes to cytology cell blocks and biopsy tissues before processing enhances specimen visualization during embedding and microtomy

Cytology specimens and biopsy tissues are frequently small and pale, making them difficult to visualize grossly in paraffin. Ten dyes were assayed on small tissues to determine if specimen discernibility could be increased during the embedding and microtomy steps in the histological process. The ideal dye should not remain visible in a tissue section microscopically after subsequent staining and must not interfere with immunohistochemistry (IHC) assays. This study found that Harris hematoxylin and 1% aq. toluidine blue solution were the best labelers for gross tissue visualization and did not adversely affect post-processing staining and IHC assays.

Targeting Peritumoral Lesions Identified by Computed Tomography and Magnetic Resonance Imaging in Feline Injection-Site Sarcomas for Microscopic Examination

Peritumoral lesions identified during in vivo imaging of feline injection-site sarcoma (FISS) are frequently interpreted as neoplastic. We recently showed that most peritumoral imaging-identified lesions (PTIILs) in FISS are non-neoplastic. In this article, we describe a protocol to target PTIIL for microscopic examination and report on the protocol's performance. Ten client-owned cats with FISS were prospectively enrolled. A fiducial marker sutured onto the skin, centered on the palpable mass, served as reference point throughout the study. Each FISS and surrounding tissue was imaged in vivo by dual phase computed tomography angiography and multiple magnetic resonance imaging pulse sequences and each PTIIL documented. Subgross measurements obtained during trimming aided localization and identification of PTIIL during microscopy. Histologic findings were categorized by descending clinical relevance: neoplastic, equivocal, non-neoplastic, within normal limits (WNL). Based on in vivo imaging resolution limits, histologic findings were ≥3 mm in at least one dimension and ≥3 mm apart. Surgical margins served as control tissue for PTIILs. Eighty-one of 87 PTIIL were examined histologically; 13 were neoplastic, 16 equivocal, and 28 non-neoplastic; 24 had no identified histologic correlate. Two neoplastic and 10 equivocal findings were located outside of PTIILs but none of them were located in sections of surgical margins. Computation of a simple confusion matrix yielded fair sensitivity (70.4%) and low specificity (59.7%) for prediction of PTIIL by histologic findings. After combining instances of normal microanatomy with non-neoplastic histologic findings, specificity increased (85.1%) and sensitivity decreased (35.8%). The protocol is a blueprint for targeting PTIIL for microscopic examination but may benefit from further refinement.

[Application of tissue-marking dyes for pathologic examination of surgical and autopsy specimens]

OBJECTIVE

To assess the applicability of imported tissue-marking dyes and the samples of experimental dyes and decorative acrylic paints to mark the resection margins of a surgical specimen.

MATERIAL AND METHODS

Three sets of tissue-marking dyes: 2 imported sets and 1 experimental set, each containing red, orange, yellow, green, blue, purple, and black dyes, and a set of decorative acrylic paints containing black, blue, light blue, green, yellow, ocher, orange, magenta, and purple dyes. The experimental dyes and imported ones were used to mark tonsillar fragments obtained at tonsillectomy. The set of experimental dyes and that of decorative acrylic paints were used to stain the fragments of autopsy specimens (the skeletal muscles, pancreas, and large bowel). The tissues obtained at autopsy were marked before and after fixation in 40% formalin for 30 min and 24 hours. The specimens were subjected to standard tissue processing. Paraffin blocks were cut into 5-μm sections that were stained with hematoxylin and eosin. To estimate resection margin marking, each specimen was examined by 7 researchers who independently assessed the covering ability of a dye and its color in the paraffin block and microslides.

RESULTS

All researchers correctly identified purple, black, and green colors from the three sets of dyes in the surgical tonsillar specimen. When examining the autopsy specimens, all the experts correctly recognized magenta and green decorative acrylic paints and black and blue experimental dyes. The time of fixation and the type of tissue did not affect the color of a dye in the paraffin block and tissue specimen.

CONCLUSION

Some of experimental dyes and decorative acrylic paints are highly competitive with imported tissue-marking dyes in their characteristics, are correctly recognized in the block and tissue specimen under a microscope, and can be proposed to mark the resection margins of the examined tissues.

Analysis and Comparison of Tissue-Marking Dye Detection via Light Microscopy, Telemicroscopy, and Virtual Microscopy

Objectives

To examine the fidelity of ink color identification using light microscopy (LM), telemicroscopy (TM), and virtual microscopy (VM).

Methods

Twenty H&E-stained frozen section slides, prepared after tissue inking with five stain combinations, were assessed by three pathologists using LM, TM, and VM. TM was performed using Mikroscan D2 slide scanner/LiveQ software with various objectives. VM was performed using Mikroscan D2 scanner/Qumulus software, specimens digitized at20×.

Results

Sensitivity/specificity by LM was 100%/100% for all colors. TM showed high overall specificity but poor sensitivity, particularly red (54%). VM showed high specificity for all colors except black (69%) and, consequently, poor sensitivity for all colors except black (96%).

Conclusions

TMD identification via telepathology showed loss of sensitivity/specificity vs LM and highlighted the need for caution when interpreting TMDs with digital technologies and the need for validation protocols.

Curative-intent radical en bloc resection using a minimum of a 3 cm margin in feline injection-site sarcomas: a retrospective analysis of 131 cases

Objectives Owing to its highly infiltrative growth, feline injection-site sarcoma (FISS) carries a significant risk of local tumour recurrence. Parameters of possible prognostic significance (eg, tumour size and location, resection of de novo vs recurrent tumours, and achievement of tumour-free surgical margins) were examined with regard to their influence on recurrence rate (RR), disease-free interval (DFI) and survival time (ST). Methods This was a retrospective analysis of cats with FISSs located on the chest or abdominal wall or the interscapular region treated in a single institution using a standardised radical resection technique with 3 cm lateral margins and full-thickness body wall resection (tumours over chest/abdominal wall) or a minimum of two fascial planes (interscapular tumours). Results Median postoperative DFI and ST of 131 cats with FISSs was 21 and 24 months, respectively. Patients operated on for recurrent tumours were significantly more likely to die from tumour-related reasons compared with patients with de novo tumours ( P <0.001). RR and DFI in the different tumour locations were comparable ( P = 0.544 and P = 0.17, respectively). Local tumour recurrence occurred in 38.1% of the cats. Cats operated on for tumour recurrences had a significantly higher chance of another recurrence (RR 55.5% vs 33.3%; P = 0.005). Completeness of excision was determined by taking tumour bed biopsies. Tumour bed biopsies that did not contain tumour cells were associated with a significantly lower RR compared with those with tumour cells (30.5% vs 76.2%). Conclusions and relevance Depending on prognostic factors such as surgery for primary vs recurrent tumour, tumour-free resection margins and tumour location, the RR in FISS ranges from 33-55%, despite curative intent radical surgery. This study may help in identifying patients at risk for recurrence.

Histologic processing artifacts and inter-pathologist variation in measurement of inked margins of canine mast cell tumors

Although quantitative assessment of margins is recommended for describing excision of cutaneous malignancies, there is poor understanding of limitations associated with this technique. We described and quantified histologic artifacts in inked margins and determined the association between artifacts and variance in histologic tumor-free margin (HTFM) measurements based on a novel grading scheme applied to 50 sections of normal canine skin and 56 radial margins taken from 15 different canine mast cell tumors (MCTs). Three broad categories of artifact were 1) tissue deformation at inked edges, 2) ink-associated artifacts, and 3) sectioning-associated artifacts. The most common artifacts in MCT margins were ink-associated artifacts, specifically ink absent from an edge (mean prevalence: 50%) and inappropriate ink coloring (mean: 45%). The prevalence of other artifacts in MCT skin was 4-50%. In MCT margins, frequency-adjusted kappa statistics found fair or better inter-rater reliability for 9 of 10 artifacts; intra-rater reliability was moderate or better in 9 of 10 artifacts. Digital HTFM measurements by 5 blinded pathologists had a median standard deviation (SD) of 1.9 mm (interquartile range: 0.8-3.6 mm; range: 0-6.2 mm). Intraclass correlation coefficients demonstrated good inter-pathologist reliability in HTFM measurement (κ = 0.81). Spearman rank correlation coefficients found negligible correlation between artifacts and HTFM SDs ( r ≤ 0.3). These data confirm that although histologic artifacts commonly occur in inked margin specimens, artifacts are not meaningfully associated with variation in HTFM measurements. Investigators can use the grading scheme presented herein to identify artifacts associated with tissue processing.

Surgical margins in the veterinary cancer patient

In veterinary oncologic specimens, histopathology is the gold standard for determining adequacy of excision. Despite limitations of this technique, the pathologist's interpretation of margin status significantly impacts patient management, including indications for adjuvant therapy. This article aims to summarize peer-reviewed literature as it relates to histologic margin evaluation in veterinary cancer patients. The value of histologic tumour-free margins and technical factors influencing histopathologic margin outcomes are also discussed. We review alternative strategies for determining excisional status, and discuss how an evolving understanding of tumour biology might inform clinical and research perspectives on surgical margins. In doing so, we aim to provide context and a stimulus for future investigations into this important yet incompletely understood topic.