Influence of formalin fixation on tissue dimensions in palatal tonsils

Surgical Margin Determination in the Era of HPV-Positive Oropharyngeal Cancer

OBJECTIVES/HYPOTHESIS

The goal of head and neck cancer surgery is the complete resection of tumor with a cuff of healthy tissue. A 5-mm margin is optimal but not always achievable in the oropharynx. We aimed to identify a consensus of definition and management of close margins for human papilloma virus (HPV)-associated oropharyngeal cancer without other risk factors.

STUDY DESIGN

Descriptive survey.

METHODS

A survey of the American Head and Neck Society (AHNS) was conducted to evaluate the abovementioned objectives by presenting hypothetical scenarios and asking questions regarding management.

RESULTS

One-hundred fifty-five AHNS members completed the survey (18% response rate). Close margins were defined as <5 mm, <3 mm, and <1 mm by 27.7%, 32.3%, and 32.3% of respondents. There was no significant difference in margin determination with experience level (P = .186). In an HPV-positive tumor with close margins, 51% chose postoperative observation. The remainder chose adjuvant radiation (22.6%), chemoradiation (1.9%), or re-excision of the wound bed (19.4%). There was no association between postoperative close margin management and experience level (P = .80).

CONCLUSION

Heterogeneity exists in the definition and management of close margins in HPV-mediated oropharyngeal carcinoma (OPSCC). Establishing a standard regarding close margins in HPV-mediated OPSCC may allow for the optimization of outcomes and help define best practices.

LEVEL OF EVIDENCE

5 Laryngoscope, 131:E2650-E2654, 2021.

Endocervical Adenocarcinoma, Gross Examination, and Processing, Including Intraoperative Evaluation: Recommendations From the International Society of Gynecological Pathologists

The International Society of Gynecological Pathologists (ISGyP) Endocervical Adenocarcinoma Project aims to provide evidence-based guidance for the pathologic evaluation, classification, and reporting of endocervical adenocarcinoma. This review presents the recommendations pertaining to gross evaluation and intraoperative consultation of specimens obtained from patients in the setting of cervical cancer. The recommendations are the product of review of published peer-reviewed evidence, international guidelines and institutional grossing manuals, as well as deliberation within this working group. The discussion presented herein details the approach to the different specimen types encountered in practice: loop electrosurgical excision procedure, cone, trachelectomy, radical hysterectomy, pelvic exenteration, and lymphadenectomy specimens. Guidelines for intraoperative evaluation of trachelectomy and sentinel lymph node specimens are also addressed. Correlation with ISGyP recommendations on cancer staging, which appear as a separate review in this issue, is also included when appropriate. While conceived in the framework of endocervical adenocarcinoma, most of the discussion and recommendations can also be applied to other cervical malignancies.

Validation of noninvasive focal depth measurements to determine epithelial thickness of the vaginal wall

OBJECTIVE

This study investigates whether noninvasive focal depth (FD) measurements correlate with vaginal wall epithelial thickness (ET). If FD accurately reflects ET of the vaginal wall, this would allow noninvasive longitudinal assessment of (newly developed) treatment modalities aiming to increase ET, without the need for invasive biopsies.

METHODS

Fourteen women, median age 62 years (inter quartile ranges: 57-65), undergoing vaginal prolapse surgery because of anterior and/or posterior compartment pelvic organ prolapse were included. We used the CytoCam, a handheld video microscope based on incident dark field imaging, and performed FD measurements of the vaginal wall before surgery. Histology was performed on tissue that was removed during the surgical procedure, and ET was measured in stained sections. We compared ET with FD interindividually, and determined the expected linear correlation and agreement between the two measurements.

RESULTS

Seventeen ET measurements (mean 125 μm ± 38.7, range 48-181 μm) were compared with 17 FD measurements (mean 128 μm ± 34.3, range 68-182 μm). The lineair correlation between the two measurements was strong (r = 0.902, P < 0.01). Bland-Altman analysis demonstrated a mean difference of 13.5 μm when comparing ET to FD.

CONCLUSIONS

The results demonstrate good agreement between ET and FD measurements. We consider the mean difference demonstrated with Bland-Altman analysis acceptable for these measurements. This suggests that FD accurately reflects ET, which further supports the use of FD to measure ET of the vaginal wall. For a complete assessment of the vaginal wall, FD measurements are preferably combined with the assessment of vaginal angioarchitecture.

Direct Comparison of the Thickness of the Parietal Peritoneum Using Peritoneal Biopsy and Ultrasonography of the Abdominal Wall in Patients Treated with Peritoneal Dialysis

Background

Long-term treatment with peritoneal dialysis (PD) results in peritoneal fibrosis. Peritoneal biopsies have been used to determine the severity of fibrosis. Ultrasonography (US) of the abdominal wall has been used to measure peritoneal thickness non-invasively. However, direct comparison of both methods in the same patient has never been done. Furthermore, the validity of US to measure peritoneal thickness has not been investigated.

Methods

We performed 3 studies: 1) a human biopsy study to compare US measurement of peritoneal thickness with histological examination; 2) a human cadaver study to investigate the effect of removing the peritoneum on US results; and 3) a phantom study in which we used US to measure the thickness of membrane-like structures with a known thickness to investigate the influence of different US settings.

Results

The median thickness in biopsies of the peritoneum was 113 μm (interquartile range [IQR] 72 –129 μm), while this was 370 μm (IQR 324 – 458 μm) when measured by US ( p < 0.0001). The mean difference between the 2 measures was -257 μm (limits of agreement -4.6 and -511 μm). In the cadaver study, removal of the peritoneum did not have an effect on the presence or thickness of the hyperechoic line reported to represent the peritoneum. In the phantom study, results were highly dependent on frequency of the transducer, scan depth, and gain settings.

Conclusions

Ultrasonography results differ markedly from histological measurement using peritoneal biopsies. However, the hyperechoic line generated by US represents the interface between 2 neighboring tissues and not a separate morphological structure. Moreover, its thickness is greatly influenced by user-defined US settings.

Tissue expansion of lung bronchi due to tissue processing for histology - A comparative analysis of paraffin versus frozen sections in a pig model

AIM

Tissue shrinking due to fixation and processing is well known. However, the degree of shrinking varies significantly with the tissue type as well as the processing method and is not well studied in various tissues. In daily pathological routine workflow, histological specimens from frozen and paraffin sections are performed from the same tissue. In the present study we compared the thickness of bronchus walls obtained from paraffin and frozen sections.

METHODS

Pig lungs were frozen in ventilated condition in liquid nitrogen and 36 bronchi were isolated after dissection. Frozen sections of 5 μm thickness were performed and the remaining tissue was fixed and embedded in paraffin after fixation in 4% formalin. Frozen and paraffin sections from the same cutting edge were analysed after haematoxylin and eosin staining by measuring the wall thickness of the bronchi using high power fields of 400-fold magnification. In each bronchus 40 measurements were implemented at different wall positions distributed over the entire wall area. Summed up, in each group 1440 wall measurements were performed in total. Statistical analysis was conducted using the Wilcoxon test and t-test as well as Pearson's correlation coefficient with a significance level at P < 0.05.

RESULTS

The bronchial wall thickness was significantly (p < 0.001) smaller in frozen sections (median: 0.50 mm; min: 0.37 mm; max: 0.97 mm) compared to paraffin sections (median: 0.58 mm; min: 0.35 mm; max: 1.06 mm). The median difference between paraffin and frozen sections was 0.05 mm (min: -0.11 mm; max: 0.22 mm). The wall thickness ratio of both groups was as follows: frozen/paraffin section = 0.8609, thus yielding a difference between paraffin and frozen of 13.91%. High correlation was found between wall thickness measurements on paraffin and frozen sections (R = 0.87, p < 0.001).

CONCLUSIONS

The bronchus wall thickness in the frozen section was 14% reduced compared to the paraffin section. In routine pathology as well as in scientific studies these results are of relevance, as airway wall thickness represents a relevant marker for pathological interpretation, especially using CT image techniques.

The Role of Conventional Ultrasonography in the Evaluation of Antrum Wall Thickness in Obese Patients

BACKGROUND

The objective of this study is to evaluate the utility of conventional ultrasonography (USG) in the evaluation of the stomach antrum and distal corpus lesions.

METHODS

A prospective evaluation was made of 69 patients who underwent sleeve gastrectomy. Preoperative USG was applied to the patients and measurements were taken and recorded of the stomach antrum full layer wall thickness (USGFT) and of mucosal thickness (USGMT). Postoperatively, same parameters were again measured histopathologically and the pathological full thickness (PFT) and pathological mucosal thickness (PMT) values were compared.

RESULTS

When evaluation was made in respect of USG and pathological measurements, the USGFT was 8.51 ± 3.07 (range 4.5-15.8) and USGMT was 5.80 ± 2.15 (range 2.36-10.5). The PFT was determined as 8.13 ± 2.24 (range 4-14) and PMT as 5.53 ± 1.86 (range 2-10.5). In the histopathological examination, gastritis was seen in 53 (76.8 %) patients and Helicobacter pylori (HP) positivity was determined in 32 (46.4 %) patients. When the patients were grouped as obese (BMI ≤ 49.9 kg/m²) (group 1, n = 50) and super obese (BMI ≥ 50 kg/m²) (group 2, n = 19), no difference was determined between the groups ultrasonographically or histopathologically (p > 0.05). The antrum wall thickness was seen to be significantly greater in the patients with gastritis and HP positivity compared to the patients who were negative. In ROC analysis, cutoff values were calculated for USGFT (5.86 mm) and USGMT (4.49 mm). In gastritis diagnosis, the USGFT cutoff value was found to have 796 % sensitivity and 68.7 % specificity.

CONCLUSION

USG was seen to be an extremely effective method in visualising the antrum wall and gastritis diagnosis can be made comfortably from the wall thickness measurement.

Accuracy of Schneiderian membrane thickness: a cone-beam computed tomography analysis with histological validation

OBJECTIVES

Cone-beam computed tomography (CBCT) has been used in the literature to evaluate Schneiderian membrane thickness (SMT), but its accuracy has never been validated. The primary aim of this study was to compare the SMT measured by CBCT to the gold standard histological assessment. The correlations between SMT and anatomical structures of the maxillary sinus and alveolar bone were also tested.

MATERIALS AND METHODS

Fourteen fresh cadaver heads were used for the study, and 28 sinus lift augmentation procedures were performed to obtain the membrane samples. Samples were fixed in formalin and stained with hematoxylin-eosine and Masson trichrome. Specimens were measured by optic microscope at three points, and a mean was obtained. Anatomical landmarks were used to accurately position the CBCT slice, so the SMT could be measured in predetermined locations. Wilcoxon signed-rank test was used to compare values of histological and CBCT measurements, and Spearman's correlation coefficient was calculated to examine the relationship between thickness and anatomical parameters.

RESULTS

A total of 597 histological measurements were performed, and the mean SMT thickness was 0.30 ± 0.17 mm. The mean CBCT membrane thickness was 0.79 ± 0.52 mm. A statistically significant difference from histological and radiological readings was observed (P = 0.000). Interestingly, 87.77% histological measurements had membrane less than 0.5 mm in thickness compared to 26.66% in CBCT assessment.

CONCLUSIONS

Within the limitation of this study, the median histological Schneiderian membrane thickness was 0.30 mm. Cone-beam computed tomography assessment was 2.6 times higher than the histological examination.

Influence of different fixation protocols on the preservation and dimensions of cardiac tissue

Recent extensive progress in invasive cardiac procedures has triggered a wave of dozens of heart morphometric anatomical studies that are carried out largely using autopsied samples fixed in formaldehyde solution prior to observations and measurements. In reality, very little is known about changes in heart tissue dimensions during fixation. The aim of this study was therefore to investigate how fixation affects the dimensions of cardiac tissue, and if different types and concentrations of reagents affect this phenomenon. A total of 40 pig heart samples were investigated, and seven different measuring sites were permanently marked in every heart prior to fixation. Four study groups (n = 10 each) were assembled that differed only in concentration and the type of fixative: (i) 2% formaldehyde solution; (ii) 4% formaldehyde solution (formalin); (iii) 10% formaldehyde solution; (iv) alcoholic formalin. The samples were measured before and after fixation at the following time points: 24 h, 72 h and 168 h. It was found that different fixatives significantly affected different parameters. Almost all of the heart dimensions that were measured stabilized after 24 h; later changes were statistically insignificant in the point-to-point comparison. Change in the length of the interatrial septum surface was not altered significantly in any of the fixatives after 24 h of preservation. It was found that 10% formaldehyde increased the thickness of muscular tissue only after 24 h; this thickening was reduced after 72 h and was insignificant at 168 h. Other heart parameters in this group do not present significant changes over the entire fixation time duration. In conclusion, the 10% formaldehyde phosphate-buffered solution appeared to be the best fixative among the fixatives that were studied for cardiac morphometric purposes; this solution caused the smallest changes in tissue dimensions. Measurements should be obtained at least after 1 week of preservation when most parameters exhibit the smallest changes compared with the non-preserved samples.

Correcting the Shrinkage Effects of Formalin Fixation and Tissue Processing for Renal Tumors: toward Standardization of Pathological Reporting of Tumor Size

Given the importance of correctly staging renal cell carcinomas, specific guidelines should be in place for tumor size measurement. While a standard means of renal tumor measurement has not been established, intuitively, tumor size should be based on fresh measurements. We sought to assess the accuracy of postfixation and microscopic measurements of renal tumor size, as compared to fresh measurements and radiographic size. Thirty-four nephrectomy cases performed by a single surgeon were prospectively measured at different time points. The study cases included 23 clear cell renal cell carcinomas, 6 papillary renal cell carcinomas, and 5 other renal tumors. Radiologic tumors were 12.1% larger in diameter than fresh tumors (P<0.01). Furthermore, fresh specimens were 4.6% larger than formalin-fixed specimens (P<0.01), and postfixation measurements were 7.1% greater than microscopic measurements (P<0.01). The overall mean percentage of shrinkage between fresh and histological specimens was 11.4% (P<0.01). Histological processing would cause a tumor stage shift from pT1b to pT1a for two tumors in this study. The shrinkage effects of formalin fixation and histological processing may result in understaging of renal cell carcinomas. The shrinkage factor should be considered when reporting tumor size.

Tumor shrinkage associated with whole-mount histopathologic techniques in oral tongue carcinoma

Shrinkage artifact of tumor tissue from histologic processing has not been rigorously quantified, particularly where the entire tumor is represented in a whole-mount specimen. Fourteen patients underwent partial-glossectomy for oral tongue carcinoma (OTC). Specimens were embedded into agar, cut into 3 mm blocks and photographed (macroscopic image), prior to histopathologic processing. Histology slides were digitized. Contours were made of tumor on both image sets and area plotted against block position. Volume estimates were mathematically derived based on these plots. The tumors shrank in volume by 20.2% (p=0.0006) on average; shrinkage by area ranged for all image pairs 0-48%. Tumor volume>median was significant in absolute shrinkage (p=0.002) but not percent shrinkage (p=0.42). Age, gender, and T stage were independent of shrinkage. This data shows whole-mount techniques produce shrinkage artifact in OTC that varies between tumors and blocks in the same tumor. In order to account for shrinkage, measurement must be performed case-by-case.

Gingiva laser welding: preliminary study on an ex vivo porcine model

OBJECTIVE

The use of lasers to fuse different tissues has been studied for 50 years. As none of these experiments concerned the oral soft tissues, our objective was to assess the feasibility of laser gingiva welding.

MATERIALS AND METHODS

Porcine full-thickness gingival flaps served to prepare calibrated samples in the middle of which a 2 cm long incision was closed, either by conventional suture or by laser tissue welding (LTW). To determine the irradiation conditions yielding the best tensile strength, 13 output power values, from 0.5 to 5 W, delivered either at 10 Hz or in continuous wave mode, were tested on six indocyanine green (ICG) concentrations, from 8% to 13% (588 samples). Then, some samples served to compare the tensile strength between the laser welded and the sutured gingiva; the other samples were histologically processed in order to evaluate the thermal damage extent. The temperature rise during the LTW was measured by thermocouples. Another group of 12 samples was used to measure the temperature elevation by thermal camera.

RESULTS

In the laser welding groups, the best tensile strength (p<0.05) was yielded by the 9% ICG saline solution (117 mM) at 4.5 W, 10 Hz, and a fluence of 31.3 kJ/cm(2). The apposition strength revealed no statistically significant difference (p<0.05) between the sutured and the laser welded gingiva at 4.5 W, 10 Hz, and 9% ICG solution. The mean temperature was 74±5.4°C at the upper surface and 42±8.9°C at the lower surface. The damaged zone averaged 333 μm at the upper surface.

CONCLUSIONS

The 808 nm diode laser associated with ICG can achieve oral mucosa LTW, which is conceivable as a promising technique of gingival repair.