Keywords: pigmented-lesion clinic, malignant melanoma, diagnosis, Breslow thickness.

Transcription

1 British Journal of Plastic Surgery (2001), 54, The British Association of Plastic Surgeons doi: /bjps A 6 year prospective analysis of the diagnosis of in a pigmented-lesion clinic: even the experts miss s, but not often C. G. Duff, D. Melsom, H. S. Rigby*, J. M. Kenealy and P. L. Townsend Departments of Plastic and Reconstructive Surgery, and *Histopathology, Frenchay Hospital, Bristol, UK SUMMARY. We investigated whether the pigmented-lesion clinic (PLC) run by the Department of Plastic and Reconstructive Surgery at Frenchay Hospital was effective in making and excluding the diagnosis of malignant melanoma, by looking at the pattern of referrals over time, the number of melanomas excised and melanomas in which the diagnosis was delayed or missed. We also investigated whether the PLC was having an effect on the thicknesses of melanomas excised. All 9968 patients attending the PLC between 1 January 1993 and 31 December 1998 were included in the study and 586 s were diagnosed; 24.7% of excisions led to the diagnosis of malignant melanoma. Seven invasive melanomas and two lentigo malignas were missed. There was one histological false negative. The PLC has a sensitivity of 98.5% and specificity of 89.2% for the diagnosis of melanoma; the negative predictive value is 99.9%. The PLC is effective in rapidly making or excluding the diagnosis of, but has had no effect on the average thickness of melanomas excised over the 6 year study period The British Association of Plastic Surgeons Keywords: pigmented-lesion clinic,, diagnosis, Breslow thickness. The incidence of is increasing in Caucasian populations. 1 4 Despite improvements in the treatment of other malignancies, the only treatment that improves the prognosis in is early diagnosis and excision. With this in mind, pigmentedlesion clinics (PLCs) were established across the UK in the 1980s in an effort to diagnose and excise malignant melanomas while they are thinner. The majority of reported series in the UK have been from units where dermatologists with an interest in melanoma run the clinic. Reports from these and other clinics have shown that the clinical diagnosis of melanoma remains difficult. 5 9 At least one clinic has successfully achieved the goal of earlier excision of melanomas, as indicated by a reduction in the mean Breslow thickness of melanomas excised in the PLC compared with those of a population not served by a PLC. 10 Other units have found no effect on the thicknesses of melanomas in areas with a PLC The rapid-access PLC at Frenchay Hospital was set up in 1993, run by first one and then two consultant plastic surgeons, each with an interest in the diagnosis and management of. The structure of the clinic and the possible outcomes for patients attending the clinic have already been reported. 14 This study reports on the accumulated data since the clinic began. Patients are referred by their family practitioners to the clinic, which runs once a week. A consultant examines all These data were presented at the Summer Meeting of the British Association of Plastic Surgeons, Belfast, July lesions with a dermatoscope. A junior surgeon operates in a dedicated theatre suite, acting on the advice of the consultant. A medical photographer is in attendance. The consulting room in the clinic provides an excellent teaching opportunity for both basic and higher surgical trainees who can examine patients under the supervision of the consultant. This study reports the numbers and patterns of patients attending the PLC each year, the numbers and types of cutaneous malignancies diagnosed and the melanomas in which the diagnosis was delayed or missed. Methods The clinic has held a dedicated database that has been collected prospectively since the clinic began. This database was analysed and, where deficiencies in the data existed, the hospital PAS and the database in the Pathology Department were consulted. To search for missed melanomas the Melanoma Registry was cross-referenced with the PLC database using the hospital number as the unique identifier. The data were collated and analysed using Microsoft Access and statistical analysis was performed using SPSS software (Kruskal Wallace non-parametric oneway analysis of rank sums). Results In the 6 years from 1 January 1993 to 31 December 1998, appointments were made and 9968 patients attended a total of appointments; 1623 appointments were 317

2 318 British Journal of Plastic Surgery missed (13.5%). Patients who missed their first appointment were offered a further appointment but 23.3% of these patients never attended the clinic. Overall, 65% of patients were female. The number of patients attending the clinic each year is shown in Figure 1. There was a marked seasonal variation with almost twice as many patients attending in the summer as in the winter (Fig. 2). A total of 2372 excisions were undertaken, of which 1256 were done immediately; 1422 (60%) of the biopsies were undertaken on women. The breakdown of histological diagnoses is given in Table 1. The number of benign lesions excised each year fell from a peak of 275 in 1994 to 121 in 1998 (Fig. 3). Over the whole study period, 586 melanomas were excised; 61.9% of patients with a diagnosis of melanoma were female. The incidence rate of melanoma within the clinic population was 5.65%. There was a seasonal variation in the diagnosis of melanoma, as there was with patients attending the clinic (Fig. 4). Overall, 24.7% of excisions led to the diagnosis of melanoma. The mean thicknesses of the melanomas diagnosed each year are shown in Figure 5. The reduction in the mean thickness of melanoma diagnosed between 1993 and 1994 was almost significant (P 0.051); however, this trend did not continue in subsequent years (P 0.09, test statistic 9.42, 5 d.f.). The proportions of in-situ, thin, intermediate and thick melanomas are shown in Figure 6. Figure 3 Number of benign lesions excised each year. Figure 1 Number of patients attending the PLC each year. Figure 2 Total number of patients attending each month over the 6 year study period. Figure 4 Total number of melanomas diagnosed each month over the 6 year study period. Table 1 Histological analysis of lesions excised and subtypes of All lesions Malignant melanomas malignant 586 superficial 462 (125 in situ) melanoma spreading basal cell 316 acral 9 (3 in situ) carcinoma lentigenous squamous cell 97 nodular 35 carcinoma atypical/ 195 lentigo maligna 13 dysplastic melanoma benign 1164 lentigo maligna 58 other 14 other 9 Total 2372 Total 586 Figure 5 Mean Breslow thickness of s excised each year.

3 A 6 year prospective analysis of the diagnosis of in a pigmented-lesion clinic 319 Figure 6 Proportions of different thickness s by year. Table 2 Details of missed melanomas Age Sex Type Delay Site (years) (months) 51 M lentigo maligna 37 nose 76 F lentigo maligna 8 forehead 26 F superficial spreading 5 leg 38 F superficial spreading 23 calf 36 F superficial spreading 13 thigh 87 F superficial spreading 41 ankle 63 F superficial spreading 28 arm 27 F superficial spreading 21 back 63 F superficial spreading 16 ankle 31 M spitzoid melanoma * 0 back * Histological false negative. Our search identified nine s in which the diagnosis was missed or delayed; all but one of these were diagnosed on a subsequent visit to the PLC. Two of these missed melanomas were lentigo malignas, the rest were of superficial spreading type varying from 0.6 to 1.37 mm in Breslow thickness. The delay in diagnosis of the missed melanomas varied from 5 to 41 months (Table 2). There was one histological false negative. From the data the sensitivity and specificity of the PLC in diagnosing melanoma was calculated. The sensitivity (true positives/(true positives false negatives)) of the clinic is 98.5%. The specificity (true negatives/(true negatives false positives)) for melanoma is 89.2%. The negative predictive value for the clinic for diagnosis of melanoma is 99.9%. Discussion In order to decrease the mortality of, the concept of the PLC was introduced during the mid 1980s with the aim of providing specialist management of people with pigmented lesions. Many regions in the UK, USA and Australia set up PLCs. These clinics essentially assumed that early detection of would yield a greater number of thinner lesions, which would lead indirectly to an improved prognosis for the population served. 15 This assumption has proved to be somewhat over-simplified. This is the largest series reported in the literature, and the results of our prospective analysis show that the PLC is effective in making or excluding the diagnosis of melanoma, with a sensitivity of 98.5% and specificity of 89.2%. The published literature for the diagnosis of melanoma falls into four categories. The first type of paper comments on the clinical signs that point to the diagnosis of melanoma; MacKie 16 developed the sevenpoint checklist for this purpose and this has been assessed. 8,17 The second type of paper looks at malignant melanomas after diagnosis and calculates the proportion of these that were correctly diagnosed preoperatively. 5,8,18 The third type of paper looks at a screened cohort and seeks to identify melanomas that were missed (our study falls into this category). 13,17,19,20 The fourth type of paper looks at groups of doctors who are shown patients with pigmented lesions, or clinical pictures of lesions, of which the histology is known or subsequently determined, and asked to make a diagnosis and management plan for each lesion. 6,21 The conclusion from these papers is that the clinical diagnosis of melanoma remains difficult and the sensitivity can vary from 50% to 100%. Despite this, the diagnosis of is not often missed because many equivocal and benign lesions are excised, putting both the physician s and the patient s minds at rest. This gives a high false-positive rate, which is deemed acceptable because it is more desirable to over-diagnose than to under-diagnose melanoma. 8 The rate of false-positive biopsies can be calculated as: falsepositive rate 1 (number of melanomas diagnosed/ number of excisions). Alternatively, we propose the concept of the strike rate, which can be calculated as: strike rate (%) (number of melanomas diagnosed/number of excisions)ε100. In the published literature the strike rate varies from 0.6% to 12.9%. In this study the strike rate was 24.7%. In other words, almost one in four excisions led to the diagnosis of melanoma in the PLC. This is at the expense of missed melanomas. A false-negative rate of 0% could be achieved by undertaking excision biopsy on all patients attending the clinic. This has financial implications that cannot currently be accommodated and causes excess morbidity. The clinical experience and expertise of the personnel involved in running the clinic has been emphasised in some studies. 5,6,8,22 It has become apparent, with the reduction in numbers of benign lesions excised, that there is a learning curve in the ability to differentiate benign from malignant lesions. We believe that the dermatoscope also plays an important role in the diagnosis of, helping the clinician to exclude the diagnosis of melanoma with greater confidence without submitting the patient to excision biopsy. This may go some way towards explaining the diminishing number of benign lesions excised each year. Other series have also suggested that the dermatoscope plays a useful role in the

4 320 British Journal of Plastic Surgery diagnosis of pigmented cutaneous lesions, further improving the diagnostic skills of specialist clinicians. 23,24 It has not been possible from our data to calculate the positive and negative predictive values for each type of cutaneous lesion, only a negative predictive value for. The reason for this is that the proforma on which the clinic data are collected allows more than one diagnosis to be entered. If, in the future, the clinician is asked to record only a single diagnosis then positive and negative predictive values can be calculated not only for melanoma but also for benign and atypical lesions and for other cutaneous tumours. There is a marked seasonal variation in numbers of patients attending the PLC and also in numbers of melanomas diagnosed. This effect has also been seen in other series. 13,25 We propose that people are more aware of their skin and any abnormalities in it during the summer months. Alternatively, there may be a genuine rise in the incidence of melanoma during the summer. This study has no control population, that is, one that does not have access to a PLC. However, comparisons within the clinic population can be made over time. There has been no significant reduction in the mean Breslow thickness of melanomas diagnosed, although a trend towards thinner melanomas was observed between the first and second years. A significant reduction in the mean thickness of melanomas diagnosed was seen in Scotland following a publicity campaign raising awareness of the improved prognosis following the earlier detection of and the patient s subsequent referral to a PLC. 10,26 Similar effects have been seen in Middlesex, UK. 25 A trend towards thinner melanomas was seen in the PLC after 2 years in another series; 27 other studies have failed to identify a significant effect of the PLC and/or publicity on the mean thickness of melanoma at diagnosis. 11,12,28,29 It is surprising that in a rapid-access clinic such as this there was a high rate of missed appointments. This may reflect the speed with which the patients are given an appointment and their inability to rearrange their schedules at short notice. All patients who did not attend their initial clinic appointment were sent a further appointment. If this subsequent appointment was missed then a letter was sent to the referring practitioner asking them to check the patient s details. The patient was not sent a further appointment unless requested by the referring doctor. In conclusion, our PLC confers benefit on the population that it serves by providing rapid access to experts with an interest in melanoma, who make or exclude the diagnosis of melanoma with a sensitivity of 98.5% and a negative predictive value of 99.9%. This allays patients fears at a time when is the subject of much and varied publicity. Minor changes to the way in which the clinic is run will allow calculation of sensitivity and specificity in statistics for the diagnosis of other cutaneous lesions in the future. The numbers of patients attending continues to rise each year and more melanomas are excised each year. One effect that we have not seen in the clinic is a reduction in the mean thickness of melanomas diagnosed, which is an accepted prognostic indicator. The clinic will continue to run, at a time when the UK Government moves to a position where all potential cancer patients must be seen within 2 weeks of referral. Acknowledgements We would like to thank Jo Hawkins, secretary of the PLC, for administrative help, and the Melanoma Register for access to their database. We thank Dr Christine Rogers and Kathryn Waters of the Research and Development Department of North Bristol NHS Trust, who provided statistical advice and analysis. References 1. Chang AE, Karnell LH, Menck HR. The National Cancer Data Base Report on cutaneous and noncutaneous melanoma. Cancer 1998; 83: Buettner PG, Raasch BA. Incidence rates of skin cancer in Townsville, Australia. Int J Cancer 1998; 78: Saxe N, Hoffman M, Krige JE, Sayed R, King HS, Hounsell K. Malignant melanoma in Cape Town, South Africa. 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5 A 6 year prospective analysis of the diagnosis of in a pigmented-lesion clinic Akasu R. Diagnosis and differential diagnosis of malignant melanoma by dermatoscope and videomicroscope. J Dermatol 1994; 21: Grover R, Ross DA, McKelvie M, Morgan BDG. Improving the early detection of. Ann R Coll Surg Engl 1996; 78: Herd RM, Cooper EJ, Hunter JAA, et al. Cutaneous malignant melanoma. Publicity, screening clinics and survival the Edinburgh experience Br J Dermatol 1995; 132: Doherty VR, MacKie RM. Reasons for poor prognosis in British patients with cutaneous. BMJ 1986; 292: Del Mar CB, Green AC, Battistutta D. Do public media campaigns designed to increase skin cancer awareness result in increased skin excision rates? Aust N Z J Public Health 1997; 21: Graham-Brown RAC, Osborne JE, London SP, et al. The initial effects on workload and outcome of a public education campaign on early diagnosis and treatment of in Leicestershire. Br J Dermatol 1990; 122: J. M. Kenealy FRACS(Plast), Consultant Plastic and Reconstructive Surgeon P. L. Townsend FRCS, FRCS(C), Consultant Plastic and Reconstructive Surgeon Department of Plastic and Reconstructive Surgery, H. S. Rigby MD, FRCS, FRCPath, Consultant Histopathologist Department of Histopathology, North Bristol NHS Trust, Frenchay Hospital, Frenchay Park Road, Frenchay, Bristol BS16 1LE, UK. Correspondence to Mr C. G. Duff, Department of Reconstructive Plastic and Burns Surgery, Northern General Hospital NHS Trust, Herries Road, Sheffield S5 7AU, UK. Paper received 25 January Accepted 21 August 2000, after revision. Published online 4 April The Authors C. G. Duff MA, FRCSEd, Clinical Research Fellow D. Melsom BSc, FRCS, Formerly Senior House Officer