Histopathological diagnosis of small melanocytic lesions suspicious for malignant melanoma

Abstract

The concern about malignant skin neoplasms leads to the excision of smaller lesions. This study on small melanocytic lesions aims to evaluate the range of possible histopathological diagnoses, describe histopathological aspects, and assess the usefulness of serial histological sections. We performed a cross-sectional descriptive histopathological study examining 76 pigmented skin lesions up to 6 mm in diameter. Histopathological diagnoses included atypical melanocytic nevi (n=38), common melanocytic nevi (n=18), atypical lentiginous melanocytic hyperplasia with architectural features of atypical melanocytic nevi (n=7), lentigo simplex (n=2), and malignant melanoma (n=1). Ten cases were non-diagnostic. Cytological atypia was not an exclusive finding of atypical lesions. Examination of serial sections did not change histopathological impression. Early detection of malignant melanoma is important, but clinical and dermoscopy exams may be leading to the resection of a great number of benign lesions. Strict attention to histopathological criteria results in a large number of non-diagnostic cases.

Figure 1

Malignant melanoma in situ. Junctional melanocytic proliferation with severe cytological atypia and focal pagetoid dissemination. Acanthosis, pigmentation of basal queratinocytes, and inflammatory infiltrate around ectatic vessels associated(Hematoxylin & eosin ×100)

Figure 2

Non-diagnostic case. Junctional melanocytic proliferation with severe cytological atypia and spitzoid features in an 18-year-old boy (Hematoxylin & eosin x400)