The impact of partial biopsy on histopathologic diagnosis of cutaneous melanoma: experience of an Australian tertiary referral service.
OBJECTIVE
To compare partial and excisional biopsy techniques in the accuracy of histopathologic diagnosis and microstaging of cutaneous melanoma.


METHODS
Prospective case series.


METHODS
Tertiary referral, ambulatory care, institutional practice. Patients Consecutive cases from 1995 to 2006. Interventions Partial and excisional biopsy. Other factors considered were anatomic site, physician type at initial management, hypomelanosis, melanoma subtype, biopsy sample size, multiple biopsies, and tumor thickness.


METHODS
Histopathologic diagnosis (false-negative misdiagnosis-overall or with an adverse outcome-and false-positive misdiagnosis) and microstaging accuracy. Odds ratios (ORs) and 95% confidence intervals (CIs) obtained from multinomial logistic regression.


RESULTS
Increased odds of histopathologic misdiagnosis were associated with punch biopsy (OR, 16.6; 95% CI, 10-27) (P < .001) and shave biopsy (OR, 2.6; 95% CI, 1.2-5.7) (P = .02) compared with excisional biopsy. Punch biopsy was associated with increased odds of misdiagnosis with an adverse outcome (OR, 20; 95% CI, 10-41) (P < .001). Other factors associated with increased odds of misdiagnosis included acral lentiginous melanoma (OR, 5.1; 95% CI, 2-13) (P < .001), desmoplastic melanoma (OR, 3.8; 95% CI, 1.1-13.0) (P = .03), and nevoid melanoma (OR, 28.4; 95% CI, 7-115) (P < .001). Punch biopsy (OR, 5.1; 95% CI, 3.4-7.6) (P < .001) and shave biopsy (OR, 2.3; 95% CI, 1.5-3.6) (P < .001) had increased odds of microstaging inaccuracy over excisional biopsy. Tumor thickness was the most important determinant of microstaging inaccuracy when partial biopsy was used (odds of significant microstaging inaccuracy increased 1.8-fold for every 1 mm increase in tumor thickness; 95% CI, 1.4-2.4) (P < .001).


CONCLUSIONS
Among melanoma seen at a tertiary referral center, histopathologic misdiagnosis is more common for melanomas that have been assessed with punch and shave biopsy than with excisional biopsy. Regardless of biopsy method, adverse outcomes due to misdiagnosis may occur. However, such adverse events are more commonly associated with punch biopsy than with shave and excisional biopsy. The use of punch and shave biopsy also leads to increased microstaging inaccuracy.
Department of Medicine, Monash University, Melbourne, Victoria, Australia.
Jonathan C
JC
Ng
Sarah
S
Swain
John P
JP
Dowling
Rory
R
Wolfe
Pamela
P
Simpson
John W
JW
Kelly
D001706:Biopsy / Q000379:methods*; D016001:Confidence Intervals; D003937:Diagnosis, Differential; D003951:Diagnostic Errors; D005500:Follow-Up Studies; D006801:Humans; D008545:Melanoma / Q000453:epidemiology / Q000473:pathology*; D009367:Neoplasm Staging; D016017:Odds Ratio; D015995:Prevalence; D011446:Prospective Studies; D012017:Referral and Consultation; D015203:Reproducibility of Results; D012878:Skin Neoplasms / Q000453:epidemiology / Q000473:pathology*; D014739:Victoria / Q000453:epidemiology