Cutaneous melanoma

Abstract

The Seminar by John Thompson and colleagues (Feb 19, p 687)1Thompson JF Scolyer RA Kefford RF Cutaneous melanoma.Lancet. 2005; 365: 687-701Summary Full Text Full Text PDF PubMed Scopus (478) Google Scholar suggests that the accuracy of melanoma diagnosis is greater when skin surface microscopy is used in addition to standard clinical examination. In our opinion this is only partly true.Many studies on the accuracy of melanoma diagnosis are based on retrospective analysis of preoperative diagnosis of pigmented skin lesions. Accordingly, sensitivity—ie, the proportion of melanoma correctly classified over the total number of melanoma excised—has shown an average value of about 60–70%.2Wolff IH Smolle J Soyer HP Kerl H Sensitivity in the clinical diagnosis of malignant melanoma.Melanoma Res. 1998; 8: 425-429Crossref PubMed Scopus (105) Google Scholar In our experience, preoperative diagnosis of melanoma yielded a sensitivity of 54·1% in a series of 327 melanomas (mean thickness 0·67 mm, SD 1·68) consecutively excised in the period 1997–2001. Specificity was 97·3% and diagnostic accuracy—ie, the proportion of lesions (benign and malignant) correctly classified—was 92·7%. Lack of precision in the form filling process may partly explain this finding: when the term “atypical nevus”—seldom adopted by clinicians for prudential reasons—was included in the diagnosis, the sensitivity value increased to 74·9%.A higher sensitivity has been reported for in-situ melanoma than for tumours thicker than 4 mm (72·6% vs 64·8%), probably owing to the loss of well characterised features in advanced melanomas (erosion, crusting, amelanotic lesions, etc).2Wolff IH Smolle J Soyer HP Kerl H Sensitivity in the clinical diagnosis of malignant melanoma.Melanoma Res. 1998; 8: 425-429Crossref PubMed Scopus (105) Google Scholar According to these data, a common opinion is that sensitivity in clinical diagnosis of melanoma is not satisfactory, even when made by a specialist dermatologist, because of concerns about false negative diagnosis in practice.Nevertheless, physicians do not excise only well established melanomas but also many equivocal lesions to minimise the risk of leaving a melanoma unexcised (current ratio of malignant to benign excised lesions in Italy is 1:5·8).3Carli P De Giorgi V Betti R et al.Relationship between cause of referral and diagnostic outcome in pigmented lesion clinics: a multicenter survey of the Italian Multidisciplinary Group on Melanoma (GIPMe).Melanoma Res. 2003; 13: 207-211Crossref PubMed Scopus (19) Google Scholar Moreover, in retrospective studies, even melanomas not correctly classified had been eventually excised. Indeed, only a melanoma left unexcised represents a clinically relevant false negative diagnosis. It is surprising that only a few studies have investigated this problem. The lack of available data could be partly due to the difficulties in providing adequate follow-up to patients with negative screening.A study in the Netherlands failed to show any melanoma left unexcised in a series of 1551 people with negative screening.4Rampen FH Casparie-van Velsen JI van Huystee BE Kiemeney LA Schouten LJ False-negative findings in skin cancer and melanoma screening.J Am Acad Dermatol. 1995; 33: 59-63Summary Full Text PDF PubMed Scopus (60) Google Scholar And a British study identified nine out of 586 melanomas in which the diagnosis was missed or delayed, resulting in a largely acceptable sensitivity of 98·5%.5Duff CG Melson D Rigby HS Kenealy JM Townsend PL A 6 year prospective analysis of the diagnosis of malignant melanoma in a pigmented-lesion clinic: even the experts miss malignant melanomas, but not often.Br J Plast Surg. 2001; 54: 317-321Summary Full Text PDF PubMed Scopus (24) Google Scholar Situations in which a melanoma is left unexcised are probably limited to clinically “featureless” tumours. In these cases, the use of new techniques such as dermoscopy may help. However, the finding that dermoscopy reaches a better lesion classification than naked-eye examination is of little reassurance when assessed retrospectively or in lesions already planned for excision.An active search—maybe by means of linkage with the local cancer registry—is strongly advised to provide more clinically relevant information about accuracy of melanoma diagnosis for the future.We declare that we have no conflict of interest. The Seminar by John Thompson and colleagues (Feb 19, p 687)1Thompson JF Scolyer RA Kefford RF Cutaneous melanoma.Lancet. 2005; 365: 687-701Summary Full Text Full Text PDF PubMed Scopus (478) Google Scholar suggests that the accuracy of melanoma diagnosis is greater when skin surface microscopy is used in addition to standard clinical examination. In our opinion this is only partly true. Many studies on the accuracy of melanoma diagnosis are based on retrospective analysis of preoperative diagnosis of pigmented skin lesions. Accordingly, sensitivity—ie, the proportion of melanoma correctly classified over the total number of melanoma excised—has shown an average value of about 60–70%.2Wolff IH Smolle J Soyer HP Kerl H Sensitivity in the clinical diagnosis of malignant melanoma.Melanoma Res. 1998; 8: 425-429Crossref PubMed Scopus (105) Google Scholar In our experience, preoperative diagnosis of melanoma yielded a sensitivity of 54·1% in a series of 327 melanomas (mean thickness 0·67 mm, SD 1·68) consecutively excised in the period 1997–2001. Specificity was 97·3% and diagnostic accuracy—ie, the proportion of lesions (benign and malignant) correctly classified—was 92·7%. Lack of precision in the form filling process may partly explain this finding: when the term “atypical nevus”—seldom adopted by clinicians for prudential reasons—was included in the diagnosis, the sensitivity value increased to 74·9%. A higher sensitivity has been reported for in-situ melanoma than for tumours thicker than 4 mm (72·6% vs 64·8%), probably owing to the loss of well characterised features in advanced melanomas (erosion, crusting, amelanotic lesions, etc).2Wolff IH Smolle J Soyer HP Kerl H Sensitivity in the clinical diagnosis of malignant melanoma.Melanoma Res. 1998; 8: 425-429Crossref PubMed Scopus (105) Google Scholar According to these data, a common opinion is that sensitivity in clinical diagnosis of melanoma is not satisfactory, even when made by a specialist dermatologist, because of concerns about false negative diagnosis in practice. Nevertheless, physicians do not excise only well established melanomas but also many equivocal lesions to minimise the risk of leaving a melanoma unexcised (current ratio of malignant to benign excised lesions in Italy is 1:5·8).3Carli P De Giorgi V Betti R et al.Relationship between cause of referral and diagnostic outcome in pigmented lesion clinics: a multicenter survey of the Italian Multidisciplinary Group on Melanoma (GIPMe).Melanoma Res. 2003; 13: 207-211Crossref PubMed Scopus (19) Google Scholar Moreover, in retrospective studies, even melanomas not correctly classified had been eventually excised. Indeed, only a melanoma left unexcised represents a clinically relevant false negative diagnosis. It is surprising that only a few studies have investigated this problem. The lack of available data could be partly due to the difficulties in providing adequate follow-up to patients with negative screening. A study in the Netherlands failed to show any melanoma left unexcised in a series of 1551 people with negative screening.4Rampen FH Casparie-van Velsen JI van Huystee BE Kiemeney LA Schouten LJ False-negative findings in skin cancer and melanoma screening.J Am Acad Dermatol. 1995; 33: 59-63Summary Full Text PDF PubMed Scopus (60) Google Scholar And a British study identified nine out of 586 melanomas in which the diagnosis was missed or delayed, resulting in a largely acceptable sensitivity of 98·5%.5Duff CG Melson D Rigby HS Kenealy JM Townsend PL A 6 year prospective analysis of the diagnosis of malignant melanoma in a pigmented-lesion clinic: even the experts miss malignant melanomas, but not often.Br J Plast Surg. 2001; 54: 317-321Summary Full Text PDF PubMed Scopus (24) Google Scholar Situations in which a melanoma is left unexcised are probably limited to clinically “featureless” tumours. In these cases, the use of new techniques such as dermoscopy may help. However, the finding that dermoscopy reaches a better lesion classification than naked-eye examination is of little reassurance when assessed retrospectively or in lesions already planned for excision. An active search—maybe by means of linkage with the local cancer registry—is strongly advised to provide more clinically relevant information about accuracy of melanoma diagnosis for the future. We declare that we have no conflict of interest. Cutaneous melanomaAuthors' reply Full-Text PDF