Acquired Pigmented Skin Lesions: A Clinicopathological Study with 5-Hydroxymethylcytosine (5hmc) Expression

A BSTRACT Introduction: Skin has the possibility of a wide range of diseases involving the epidermis, epidermal appendages, and dermal tissue. Histopathologic examination is the gold standard for the diagnosis of skin tumors. But yet in cases of problematic pigmented skin neoplasms, clinicopathological correlation along with immunohistochemical expression of certain biomarkers, with incorporation of all the available data, are of paramount importance. “Loss of 5hmc” has been mentioned as an important epigenetic hallmark of melanoma with diagnostic and prognostic implications. Aims: To study the clinicopathological spectrum of acquired pigmented lesions of skin and to assess the diagnostic and prognostic implications of 5hmC (5 hydroxymethylcytosine) in different acquired pigmented skin lesions, especially for melanoma. Materials and Methods: It was an observational cross-sectional and single institution-based study done from January 2021 to July 2022 for a period of 18 months with a sample size of 50. The specimens were received in the Department of Pathology. Gross examination was done, and sections from the specimens were taken, followed by histopathological reporting. Immunohistochemistry was performed for 5hmC for representative tissue sections, and the score was given accordingly. Statistical analyses were performed using Graph Prism Pad. Results: Out of 50 cases of acquired pigmented skin lesions, 24 cases were melanocytic benign lesions (48%) followed by the 10 melanocytic malignant lesions (20%), 10 keratinocytic benign lesions (20%), and 6 keratinocytic malignant lesions (12%). 5hmC expression was highest among the melanocytic benign lesions (i.e., 95.00%), which was followed by 5hmC expression among keratinocytic malignant lesions (i.e., 92.17%). The distribution of 5hmC expression also showed an extremely significant association with the margin irregularity status ( P < 0.0001) and ulceration status ( P < 0.0001). For survival analysis, Kaplan-Meier curves were obtained. The P value obtained by using the Logrank test for trend by comparison of the survival curves was significant ( P = 0.0138). Conclusion: Expression of IHC markers can serve as important diagnostic tools in cases where differential diagnosis between a malignant and a benign acquired pigmented skin lesions can be very challenging at times for a pathologist on the basis of clinicopathological and histopathological findings only. They might be helpful in predicting prognosis, especially in regards to melanoma cases. 5hmC have extremely significant diagnostic as well as prognostic value among acquired pigmented skin lesions.