HISTOMORPHOLOGY & IMMUNOHISTOCHEMISTRY OF MELANOCYTIC LESIONS: A FIVE YEAR STUDY AT A TERTIARY CARE CENTRE

Abstract

BACKGROUND: Melanocytic lesions are tumors developing from melanocytes occurring at cutaneous and non-cutaneous sites. Overall cutaneous and benign ones far outnumber the non-cutaneous and malignant ones respectively. Histopathology is the current gold standard for the diagnostic classification of melanocytic neoplasms.

OBJECTIVES: To study the histopathologic spectrum and immunohistochemical profile of various melanocytic lesions.

PARTICIPANTS: Biopsy samples of patients having melanocytic lesions.

STUDY DESIGN: Retrospective-Prospective, Observational.

METHODS: In our study statistical analysis was performed using SPSS (IBM Corporation, version 23). Inclusion Criteria: Samples from initial presenting/primary lesions & Exclusion Criteria: Samples from uveal and meningeal melanocytic lesions.

RESULTS: Out of 120 patients, 62 (51.7%) were females and 58 (48.3%) males, 99 (82.5%) were cutaneous lesions and 21 (17.5%) non-cutaneous, and 62 (51.7%) benign and 58 (48.3%) malignant.  59 (59.6%) of the cutaneous lesions were benign with a female predominance and 40 (40.4%) were malignant with a predilection for males. Face was the commonest site for benign lesions and sole of foot commonest site for malignant ones. Among the 21 cases of non-cutaneous lesions, 3 (14.3%) were benign and 18 (85.7%) were malignant with oral cavity being the commonest site for non-cutaneous lesions.

CONCLUSIONS: With regards to histopathology, distinction between nevi and melanoma can usually be easily achieved using well-established morphologic criteria, however, a significant minority of these specimens can cause diagnostic difficulties. Immunohistochemistry has an important role in the diagnosis of melanocytic lesions. However, there is no single marker, or combination thereof, that establishes an unequivocal diagnosis of melanoma or nevus. Thus it is necessary to carefully analyze the pattern of expression (patchy versus diffuse) and localization (maturation) in the context of morphologic standard features.