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Là ở chỗ khối u ác tính khối u ác tính thực sự? Bởi vì phương pháp điều trị hiệu quả cho u hắc tố ác tính đã chứng minh rất khó nắm bắt đã có một sự nhấn mạnh tìm kiếm cho các tổn thương sớm. | Melanoma Critical Debates Edited by Julia A. Newton Bishop Martin Gore Copyright 2002 Blackwell Science Ltd 7 Borderline melanocytic lesions Nigel Kirkham Are in situ melanomas real melanomas Because effective treatments for malignant melanoma have proved so elusive there has been an emphasis on looking for the early lesion. It is possible to diagnose malignant melanoma both clinically and histologically at an early stage when the lesion is small flat and confined to the epidermis. This is what is meant by the term in situ melanoma . Simple excision of an in situ melanoma has the potential to produce a cure. The tumour is prevented from evolving into a larger tumour with a greater potential for metastasis 1 . This begs the question of whether in situ melanomas are real melanomas. It has been proposed that primary malignant melanomas evolve from melanocytic precursor lesions and this evolution goes through stages described as radial and vertical growth phases. The radial growth phase includes in situ melanoma but also includes microinvasive tumours and describes tumours that are not tumourigenic they lack the capacity for metastasis. The prognosis in radial growth phase is excellent irrespective of tumour thickness or other prognostic variables 2 . The biological behaviour of the intraepidermal component of radial growth phase or superficial spreading melanoma has significantly different properties to the cells in a vertical growth phase melanoma. The main debate has been about the criteria for diagnosing in situ melanoma and whether there exists a group of atypical in situ melanocytic lesions that are neither melanomas nor naevi. This debate has not usually been informed by many relevant data 3 4 . Underdiagnosis of malignancy The underdiagnosis of malignancy is not a large problem in terms of absolute numbers as most histopathologists will not make this sort of mistake very often. When it does happen it can become a very real problem for the pathologist as well as
