Histomorphological Study of Skin Epithelial Tumours with Immunohistochemical Evaluation of p53 Expression in Malignant Tumours

Abstract

Introduction: Skin is the largest organ in the body. A variety of hyperplastic growths, benign and malignant tumours are encountered in clinical practice. Although skin tumours constitute <1% in India, the prevalence has been progressively increasing over the last few decades. However, limited studies have been conducted in Indian subcontinent to study skin tumours. Reportedly, pathogenesis of skin tumours in Indians is notably distinct than that observed in white-skinned people. This highlights the high demand for studying skin tumours on a larger scale in Indian subcontinent. Moreover, genetic mutations in tumours are crucial aspects of which p53 gene mutations are predominantly involved in the development of 50% of all tumours. The expression rate and positivity of p53 has been reported to vary between white- and dark-skinned individuals, mainly Indians however, this hypothesis remains to be validated on an extensive scale. Aim: To analyse the histomorphology of skin epithelial tumors and subsequent p53 expression in malignant epithelial skin tumours. Materials and methods: A two-year observational study from July 2014-June 2016 observational study was conducted in the Pathology Department of a tertiary care hospital and included 50 biopsy specimens of benign and malignant epithelial skin tumours. All the specimens were histopathologically evaluated using haematoxylin and eosin staining technique. Moreover, the paraffin sections of specimens of malignant epithelial tumours were according to reference 12 used for analysis as mentioned in material methods. It is a semi-quantitative method. Positive and negative controls were run with each batch of slides. Results: Of all the 50 specimens, 32 (64%) and 18 (36%) were obtained from males and females, respectively. Twentyone (42%) specimens were malignant epithelial tumours, with Squamous Cell Carcinoma (SCC) (52.4%) and Basal Cell Carcinoma (BCC) (28.6%) being the most common types, whereas 26 (52%) were benign epidermal tumours, with nevi (46.15%) and seborrheic keratosis (34.61%) being the most common types. Remaining three (6%) specimens exhibited Bowen’s disease. For SCC, percentage positivity of p53 for well, moderately and poorly differentiated tumours was 38.5%, 38.3% and 45%, respectively. For BCC, malignant melanoma and verrucous carcinoma % positivity was 68.33%, 55% and 15%, respectively. Conclusion: Knowledge of histopathological patterns of skin lesions is a must, considering the distinct clinical manifestations. Such knowledge can be useful in understanding the disease prognosis and planning effective therapeutic strategies. In the present study, SCC followed by BCC was highly prevalent NMSCs, whereas melanocytic nevi and seborrheic keratosis were highly prevalent benign tumours. p53 expression is lower in Indians than white-skinned people.

Keywords

• bowen’s disease
• carcinoma
• eosin
• haematoxylin
• melanoma
• mutation
• p53 genes
• skin neoplasms