Biopsy for malignant melanoma--are we following the guidelines?

Guidelines for suspected malignant melanoma recommend a prompt, full-thickness excision biopsy allowing diagnosis and assessment of the Breslow thickness. Incisional biopsy is acceptable only for extensive facial lentigo maligna or acral melanoma. Punch, shave and other types of biopsies do not allow pathological staging and are, therefore, not recommended.

A total of 100 referrals for histology-proven malignant melanoma were assessed retrospectively over a 1-year period (2005).

Of the 100 patients included in this study, 52 were male and 48 female. Ages ranged from 18-91 years, with a mean of 63 years. Origin of referrals was: dermatology, 63%; general practitioner (GP), 33%; and other sources in the remaining 4% of cases. Malignant melanoma was suspected in 84% and a benign lesion in remaining 16% of patients. However, only 56% of the patients were seen in our unit within 14 days of the referral as per the 2-week cancer rule. In these 100 patients, various types of biopsy were performed: 50 were referred without biopsy, 17 excision, 20 punch, 3 shave, 1 curettage, and 1 incisional biopsy. The type of biopsy was not recorded in the remaining 3 patients. Of the GP group, 48% were referred without biopsy, 12% had excision and 3% had incisional biopsies. The remaining 30% were punch, shave biopsies, and even curettage, inconsistent with current recommendations. Of the dermatology group, 54% were referred without biopsy, 21% underwent excision biopsy and 22% were punch biopsies. In total, 20 punch biopsies were performed, of which 7 were for lesions on the face ranging from 1.7-25 mm in size. The remaining punch biopsies were for lesions on the trunk or limbs (4-50 mm). Of the 20 punch biopsies performed, Breslow thickness was available in only 9 cases (45%). Sixteen of the punch biopsies were done when malignant melanoma was suspected and lesion otherwise was suitable for excisional biopsy. In the GP group, 3 shave biopsies and 1 curettage were performed, of which malignant melanoma was clinically suspected in one patient. The Breslow thickness was not obtained from any of the shave biopsies or curettage cases. Of the 17 excision biopsies performed, 3 were incompletely excised (2 by dermatology and 1 by GP).

A significant proportion of biopsies are inappropriate and inconsistent with the malignant melanoma guidelines. Punch biopsies are performed even when malignant melanoma is clinically suspected and excision biopsy is feasible. Only a small proportion of patients appear to be seen on an urgent basis within 14 days of referral. Such factors can lead to a delay in diagnosis, subsequent definitive treatment and adversely affect patient outcome. This study identifies a need to provide feedback and education to sources of malignant melanoma referrals.