Nuclear morphometry in squamous cell carcinoma (SCC) of the tongue

Perspective of nuclear fractal dimension in diagnosis and prognosis of oral squamous cell carcinoma

Background:

Owing to the restricted predictive value of conventional prognostic factors and the inconsistent treatment strategies, several oral squamous cell carcinoma (OSCC) patients are still over-treated or under-treated. In recent years, computer-assisted nuclear fractal dimension (nFD) has emerged as an objective approach to predict the outcome of OSCC.

Objective:

This study is an attempt to find out the differences in nFD values of epithelial cells of normal tissue, fibroepithelial hyperplasia, verrucous carcinoma, and OSCC. Further effort to evaluate the predictive potential of nFD of tumor cells for cervical lymph node metastasis (cLNM) was also assessed.

Methodology:

Formalin-fixed paraffin-embedded blocks of OSCC tissues of patients treated with neck dissection were collected. Photomicrographs of H-&E-stained sections were subjected to the image analysis by ImageJ and Python programming to calculate nFD. The association of categorical variables with nFD was studied using cross-tabulation procedure and the Fisher exact test. Receiver operating curve analysis was performed to find out cutoff value of nFD. A logistic regression model was developed to test the individual and combined predictive potential of grading and nFD for cLNM.

Results:

A significant difference between the mean nFD of healthy cells and malignant epithelial cells was observed (P = 0.01). nFD was not found to be an independent predictor of cLNM, although nFD and grading together demonstrated significant predictive potential (P = 0.004).

Conclusion:

nFD combined with grading can predict lymph node metastasis in OSCC. To the best of our knowledge, this is the first study of its kind.

Nuclear Morphological Abnormalities in Cancer: A Search for Unifying Mechanisms

Irregularities in nuclear shape and/or alterations to nuclear size are a hallmark of malignancy in a broad range of cancer types. Though these abnormalities are commonly used for diagnostic purposes and are often used to assess cancer progression in the clinic, the mechanisms through which they occur are not well understood. Nuclear size alterations in cancer could potentially arise from aneuploidy, changes in osmotic coupling with the cytoplasm, and perturbations to nucleocytoplasmic transport. Nuclear shape changes may occur due to alterations to cell-generated mechanical stresses and/or alterations to nuclear structural components, which balance those stresses, such as the nuclear lamina and chromatin. A better understanding of the mechanisms underlying abnormal nuclear morphology and size may allow the development of new therapeutics to target nuclear aberrations in cancer.

Advances toward fully automated in vivo assessment of oral epithelial dysplasia by nuclear endomicroscopy-A pilot study

BACKGROUND

Uncertainties in detection of oral epithelial dysplasia (OED) frequently result from sampling error especially in inflammatory oral lesions. Endomicroscopy allows non-invasive, "en face" imaging of upper oral epithelium, but parameters of OED are unknown.

METHODS

Mucosal nuclei were imaged in 34 toluidine blue-stained oral lesions with a commercial endomicroscopy. Histopathological diagnosis showed four biopsies in "dys-/neoplastic," 23 in "inflammatory," and seven in "others" disease groups. Strength of different assessment strategies of nuclear scoring, nuclear count, and automated nuclear analysis were measured by area under ROC curve (AUC) to identify histopathological "dys-/neoplastic" group. Nuclear objects from automated image analysis were visually corrected.

RESULTS

Best-performing parameters of nuclear-to-image ratios were the count of large nuclei (AUC=0.986) and 6-nearest neighborhood relation (AUC=0.896), and best parameters of nuclear polymorphism were the count of atypical nuclei (AUC=0.996) and compactness of nuclei (AUC=0.922). Excluding low-grade OED, nuclear scoring and count reached 100% sensitivity and 98% specificity for detection of dys-/neoplastic lesions. In automated analysis, combination of parameters enhanced diagnostic strength. Sensitivity of 100% and specificity of 87% were seen for distances of 6-nearest neighbors and aspect ratios even in uncorrected objects. Correction improved measures of nuclear polymorphism only. The hue of background color was stronger than nuclear density (AUC=0.779 vs 0.687) to detect dys-/neoplastic group indicating that macroscopic aspect is biased.

CONCLUSIONS

Nuclear-to-image ratios are applicable for automated optical in vivo diagnostics for oral potentially malignant disorders. Nuclear endomicroscopy may promote non-invasive, early detection of dys-/neoplastic lesions by reducing sampling error.

Image analysis assisted study of mitotic figures in oral epithelial dysplasia and squamous cell carcinoma using differential stains

BACKGROUND

Mitosis is a process of cell division resulting in two genetically equivalent daughter cells. Excessive proliferation of cells due to mitosis is the hallmark in pre cancer and cancer.

AIMS

This study was conducted to count the number of mitotic figures in normal oral mucosa, oral epithelial dysplasia and squamous cell carcinoma in both Hematoxylin and Eosin (H&E) and Crystal Violet stained sections. Also the overall number of mitotic figures with both stains were compared along with the evaluation of staining efficacy of both the stains.

METHODS AND MATERIAL

The present study was conducted on 20 specimens each of the three categories. These were further divided into two groups for staining with H&E and with 1% Crystal Violet respectively. Images were captured and analyzed using image analysis software Dewinter Biowizard 4.1.

RESULTS

Comparison of mitotic figure count in three categories in sections stained with both stains showed statistically significant difference (p < 0.001). The mean number of mitotic figures seen in Crystal Violet reagent were significantly higher as seen in H&E stain (p < 0.001). The overall diagnostic efficacy of Crystal Violet was 87.6%. Crystal Violet scored over H&E stain and also helped to better appreciate metaphases in Squamous cell carcinoma and telophases in dysplasia.

CONCLUSION

Number of mitotic figures progressively increase with the advancement of the pathology. Use of 1% Crystal Violet provides better appreciation of mitotic figures and can be employed as a selective stain in routine histopathology.

Applicability of preoperative nuclear morphometry to evaluating risk for cervical lymph node metastasis in oral squamous cell carcinoma

BACKGROUND

We previously reported the utility of preoperative nuclear morphometry for evaluating risk for cervical lymph node metastases in tongue squamous cell carcinoma. The risk for lymph node metastasis in oral squamous cell carcinoma, however, is known to differ depending on the anatomical site of the primary tumor, such as the tongue, gingiva, mouth floor, and buccal mucosa. In this study, we evaluated the applicability of this morphometric technique to evaluating the risk for cervical lymph node metastasis in oral squamous cell carcinoma.

METHODS

A digital image system was used to measure the mean nuclear area, mean nuclear perimeter, nuclear circular rate, ratio of nuclear length to width (aspect ratio), and nuclear area coefficient of variation (NACV). Relationships between these parameters and nodal status were evaluated by t-test and logistic regression analysis.

RESULTS

Eighty-eight cases of squamous cell carcinoma (52 of the tongue, 25 of the gingiva, 4 of the buccal mucosa, and 7 of the mouth floor) were included: 46 with positive node classification and 42 with negative node classification. Nuclear area and perimeter were significantly larger in node-positive cases than in node-negative cases; however, there were no significant differences in circular rate, aspect ratio, or NACV. We derived two risk models based on the results of multivariate analysis: Model 1, which identified age and mean nuclear area and Model 2, which identified age and mean nuclear perimeter. It should be noted that primary tumor site was not associated the pN-positive status. There were no significant differences in pathological nodal status by aspect ratio, NACV, or primary tumor site.

CONCLUSION

Our method of preoperative nuclear morphometry may contribute valuable information to evaluations of the risk for lymph node metastasis in oral squamous cell carcinoma.

Nuclear envelope invaginations and cancer

The nuclear envelope (NE) surrounds the nucleus and separates it from the cytoplasm. The NE is not a passive structural component, but rather contributes to various cellular processes such as genome organization, transcription, signaling, and stress responses. Although the NE is mostly a smooth surface, it also forms invaginations that can reach deep into the nucleoplasm and may even traverse the nucleus completely. Cancer cells are generally characterized by irregularities and invaginations of the NE that are of diagnostic and prognostic significance. In the current chapter, we describe the link between nuclear invaginations and irregularities with cancer and explore possible mechanistic roles they might have in tumorigenesis.

Benign versus malignant parakeratosis: a nuclear morphometry study

Parakeratosis is relatively common in both benign and malignant skin diseases. It is a useful feature for classifying certain types of dermatitis; however, its value in distinguishing benign from malignant neoplastic squamous lesions has not been investigated. Parakeratotic nuclei are pyknotic and often elongated, regardless of the underlying disease. However, we have noticed a quite consistent difference in nuclear morphology between benign and malignant parakeratosis, which has not been formally described in the literature. To test the hypothesis that morphological differences may aid in the discrimination between certain benign and malignant dermatopathological lesions, we used computer-aided nuclear morphometry to analyze parakeratosis from 28 cases of squamous cell carcinoma, 19 cases of verruca vulgaris, and 23 cases of psoriasiform dermatitis. Significant differences in nuclear area and area variability were observed between benign and malignant cases. These two parameters together could separate most squamous cell carcinomas from benign cases. Through this study, we hope to raise the awareness that even parakeratosis, the most superficial morphological datum available for histopathological evaluation, may harbor distinct changes of nuclear atypia in squamous cell carcinoma. In some overly superficial shave biopsies, parakeratosis may be the only material available for evaluation. For such cases, if squamous cell carcinoma is in the differential diagnosis, then the parakeratotic nuclei should be examined carefully to determine the likelihood of malignancy. Computer-aided nuclear morphometry may have potential diagnostic value for such cases.

Molecular aspects of diagnostic nucleolar and nuclear envelope changes in prostate cancer

Prostate cancer is still diagnosed by pathologists based on subjective assessment of altered cell and tissue structure. The cellular-level structural changes diagnostic of some forms of cancer are known to be induced by cancer genes, but the relation between specific cellular-level structural features and cancer genes has not been explored in the prostate. Two important cell structural changes in prostate cancer-nucleolar enlargement and nuclear envelope (NE) irregularity-are discussed from the perspective that they should also relate to the function of the genes active in prostate cancer. Enlargement of the nucleolus is the key diagnostic feature of high-grade prostatic intraepithelial neoplasia (PIN), an early stage that appears to be the precursor to the majority of invasive prostate cancers. Nucleolar enlargement classically is associated with increased ribosome production, and production of new ribosomes appears essential for cell-cycle progression. Several cancer genes implicated in PIN are known (in other cell types) to augment ribosome production, including c-Myc, p27, retinoblastoma, p53, and growth factors that impact on ERK signaling. However, critical review of the available information suggests that increased ribosome production per se may be insufficient to explain nucleolar enlargement in PIN, and other newer functions of nucleoli may therefore need to be invoked. NE irregularity develops later in the clonal evolution of some prostate cancers, and it has adverse prognostic significance. Nuclear irregularity has recently been shown to develop dynamically during interphase following oncogene expression, without a requirement for post-mitotic NE reassembly. NE irregularity characteristic of some aggressive prostate cancers could reflect cytoskeletal forces exerted on the NE during active cell locomotion. NE irregularity could also promote chromosomal instability because it leads to chromosomal asymmetry in metaphase. Finally, NE irregularity could impact replication competence, transcriptional programming and nuclear pore function.

Nuclear envelope irregularity is induced by RET/PTC during interphase

Nuclear envelope (NE) irregularity is an important diagnostic feature of cancer, and its molecular basis is not understood. One possible cause is abnormal postmitotic NE re-assembly, such that a rounded contour is never achieved before the next mitosis. Alternatively, dynamic forces could deform the NE during interphase following an otherwise normal postmitotic NE re-assembly. To distinguish these possibilities, normal human thyroid epithelial cells were microinjected with the papillary thyroid carcinoma oncogene (RET/PTC1 short isoform, known to induce NE irregularity), an attenuated version of RET/PTC1 lacking the leucine zipper dimerization domain (RET/PTC1 Deltazip), H (V-12) RAS, and labeled dextran. Cells were fixed at 6 or 18 to 24 hours, stained for lamins and the products of microinjected plasmids, and scored blindly using previously defined criteria for NE irregularity. 6.5% of non-injected thyrocytes showed NE irregularity. Neither dextran nor RAS microinjections increased NE irregularity. In contrast, RET/PTC1 microinjection induced NE irregularity in 27% of cells at 6 hours and 37% of cells at 18 to 24 hours. RET/PTC1 Deltazip induced significantly less irregularity. Since irregularity develops quickly, and since no mitoses and only rare possible postmitotic cells were scored, postmitotic NE re-assembly does not appear necessary for RET/PTC signaling to induce an irregular NE contour.

Improved prediction of metastasis in tongue carcinomas, combining vascular and nuclear tumor parameters

BACKGROUND

Predicting the presence of metastasis, based on tumor or tumor-related characteristics is of utmost importance. The authors studied the significance of tumor DNA features and tumor-related angiogenesis to predict the occurrence of metastasis in squamous cell carcinomas (SCCs) of the tongue.

METHODS

Paraplast blocks from resection specimens of 20 metastasized and 20 nonmetastasized SCCs of the tongue with a minimum follow-up of 24 months were used. Tissue sections were stained with anti-CD34 monoclonal antibodies for vessel visualization, and according to Feulgen to stain DNA. Using image analysis, data from both stainings were computed for each of the 40 carcinomas. A logistic regression model to predict the presence of metastasis, based on vascular and nuclear morphology features, was developed.

RESULTS

The intratumor variation of chromatin condensation and the percentage vessels smaller than 5 microm in diameter were selected for the model. The model correctly predicted metastasis in 90% of patients and excluded metastasis correctly in 75% of nonmetastasized tumors. Taking into account the prevalence of metastasis in SCC of the tongue of between 30% and 60%, this means a predictive value for a negative outcome of between 95% and 83%.

CONCLUSIONS

The proposed model shows an improvement of predictive values compared with previous models with single parameters. Therefore, a multiparameter model appears to predict the multiparameter process of metastasis better.

Flow cytometric DNA ploidy analysis of oral cancer comparison with histologic grading

It has been reported that DNA content analysis provides prognostic information eliminating the subjective component involved in routine microscopic decision making. In an attempt to establish a relationship between pathological findings and flow cytometric analysis, 36 formalin-fixed, paraffin-embedded tumour tissue samples were prepared according to Hedley's method and analysed by means of an Epics Profile II flow cytometer. DNA aneuploidy was observed in 15 tumours (41%). A statistically significant correlation was identified between DNA index and mitoses, cellular response and degree of differentiation, but not the ploidy status. It was not possible to identify a significant association of sex, age, and site of the tumour to DNA index. We found a strong correlation between histologic malignancy and DNA index; an increase in DNA index as malignancy score increases was noted. It was concluded that DNA index shows a good correlation with the histologic features of oral cancer, being a complement of differentiation and histologic grading analysis. The use of DNA analysis as a complement to pathological studies would help to diminish the subjective component of assessment of head and neck cancers. Ploidy status was not statistically associated with the differentiation of tumours.