Melanocytic Lesions- A Hospital-based Descriptive Study from Central Kerala, India

Abstract

Introduction: Malignant melanoma is a tumour of melanocytic origin. There is considerable geographic variation in the incidence of melanocytic lesions and are related to exposure to sunlight and susceptibility of the population. Descriptive and statistical studies of melanocytic lesions are few among Indian populations. Aim: To describe and categorise melanocytic lesions, analyse their histological features and form evidence based data applicable to Indian population. Materials and Methods: The present descriptive study was conducted in Department of Pathology in a tertiary care centre in central Kerala, India from August 2013 to July 2016. Total duration of the study was 36 months starting from 2013 August to 2016 July. Melanocytic lesions received in Pathology Department for the study period were analysed. Data including age, gender, signs and symptoms, anatomical site, clinical and gross photographs were analysed. For each case, gross and histopathological examination were done. In some cases histopathological study alone was not diagnostic, so Immunohistochemistry (IHC) including Human Melanoma Black (HBM)-45 and Melan-A were conducted to establish melanocytic differentiation. Final statistical analysis was done by frequency measurements and cross tabulation using Statistical Package for the Social Sciences (SPSS) software version 17.0. Results: Total sample size was 57, among which 44 cases were from cutaneous sites (27 benign and 17 malignant) and 13 were from mucosal sites (2 benign and 11 malignant). Most of the cases were from above 60 years age group (35%). Anatomically, majority of cutaneous melanomas were from lower limb {15 (88.2%)} and majority of mucosal melanomas were from upper gastrointestinal tract {5 (38.4%)}. Although prominent nucleoli are said to be characteristic feature of melanomas, 8 out of the 28 total cases of melanomas had inconspicuous nucleoli (28.5%). When cell morphology of melanomas was studied, majority of cases had oval cells 10 (35.7%). It was also found that there was a significant correlation between spindle cell morphology and absence of pigment in melanomas (p-value=0.004). There was no association between mitosis in melanomas and vertical tumour diameter (p-value=0.1837). Conclusion: A female predominance was observed and the commonly effected age group was above 60 years. Intradermal nevi were the major benign melanocytic lesion, while the common site was lower limb among cutaneous melanomas and upper gastrointestinal tract among mucosal melanomas. A positive association between absence of pigment in malignant melanomas and predominance of spindle cells was found.