Think before you shave: Factors influencing choice of biopsy technique for invasive melanoma and effect on definitive management.

BACKGROUND/OBJECTIVE: Partial biopsies are sometimes used for melanoma diagnosis with anticipated time and cost savings compared to excisional biopsy. However, their impact on subsequent melanoma management is unknown. Determine factors related to choice of partial over excisional biopsy to diagnose invasive melanoma and examine the effect of partial biopsies on definitive melanoma management. METHOD: Retrospective repeated cross-sectional population-based study through the Victorian Cancer Registry of diagnosed melanomas in 2005, 2010 and 2015. A random sample of 400 patients per year, stratified by tumour thickness, was selected. RESULTS: A total of 1200 patients had 833 excisional and 337 partial biopsies. Omission of suspected diagnosis on pathology requests affected 46% (532/1151) of all diagnostic biopsies. Diagnostic suspicion did not influence preference for partial over excisional biopsy [Odds Ratio (OR) 1.2, 95%CI 0.8-1.7; P = 0.40]. The partial:excisional biopsy usage ratio was higher in patients aged > 50 years than patients aged <50 years [relative risk ratios (RRR) 1.5; 95%CI 1.0 to 2.2; P = 0.03]. In 34% and 17% of tumours diagnosed with punch and shave, respectively, three procedures were required for definitive excision instead of two, compared with 5% of excisional biopsies When partial biopsy was used, patients were at greater risk of requiring three-staged excisions when controlled for age, anatomical site, melanoma subtype and thickness (RRR 6.7; 95%CI 4.4-10.1; P < 0.001). CONCLUSION: Diagnostic suspicion does not appear to be a major factor influencing choice of biopsy technique. Using partial biopsy to diagnose melanoma often leads to an extra procedure for definitive treatment compared with excisional biopsy.

Efficacy of imiquimod cream, 5%, for lentigo maligna after complete excision: a study of 43 patients.

OBJECTIVE: To determine the efficacy of imiquimod cream, 5%, in the treatment of lentigo maligna (LM). DESIGN: Open-label before-and-after interventional study. SETTING: A multidisciplinary melanoma clinic at a major tertiary hospital. PATIENTS: Forty-three patients with biopsy-proven LM of greater than 5 mm in diameter completed this study. INTERVENTIONS: Imiquimod cream, 5%, was applied to the lesion 5 days a week for 12 weeks. The original lesion was excised with a 5-mm margin. MAIN OUTCOME MEASURES: The primary outcome was histopathologic evidence of LM in the excision specimen assessed independently by 2 of 3 dermatopathologists. Visible inflammation during treatment and macroscopic clearance were recorded. RESULTS: When 5 of the 43 patients with discordant histopathologic assessment of the excision specimen were excluded, 20 of 38 patients (53% [95% confidence interval, 36%-69%]) demonstrated histopathologic clearance of LM after imiquimod treatment. Visible inflammation was significantly associated with histopathologic clearance (P = .04), but the positive predictive value was low (62%). Macroscopic clearance showed some association with histopathologic clearance (P = .11). Dermatopathologist concordance for all 43 specimens was substantial (κ = 0.77; 95% confidence interval, 0.57-0.96). CONCLUSIONS: Imiquimod cream, 5%, has limited efficacy in the treatment of LM when determined by histopathologic assessment of the entire treated area. The clinical signs of visible inflammation during treatment and apparent lesion clearance cannot be relied on to assess efficacy.