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Journal of the American Academy of Dermatology
Sous presse. Epreuves corrigées par l'auteur. Disponible en ligne depuis le lundi 4 novembre 2019
Doi : 10.1016/j.jaad.2019.08.012
accepted : 3 August 2019
Number of skin biopsies needed per malignancy: Comparing the use of skin biopsies among dermatologists and nondermatologist clinicians

Ashley Privalle, MD a, b, Thomas Havighurst, MS c, KyungMann Kim, PhD c, Daniel D. Bennett, MD a, Yaohui G. Xu, MD, PhD a,
a Department of Dermatology, University of Wisconsin–Madison, Madison, Wisconsin 
b Department of Dermatology, Mayo Clinic, Rochester, Minnesota 
c Department of Biostatistics and Medical Informatics, University of Wisconsin–Madison, Madison, Wisconsin 

Reprint requests: Yaohui G. Xu, MD, PhD, Department of Dermatology, University of Wisconsin, One South Park St, 7th Floor, Madison, WI 53715.Department of DermatologyUniversity of WisconsinOne South Park St, 7th FloorMadisonWI53715

There are too few board-certified dermatologists to treat all patients with skin disease. Primary care physicians often serve at the frontline of skin cancer screening.


To compare biopsy use among dermatologist physicians, dermatology advanced practice professionals (APPs), primary care physicians (PCPs), and other nondermatology clinicians.


Pathology reports, requisition forms, and clinical notes of skin biopsies submitted to our institution during the study period were reviewed. Skin biopsies for inflammatory conditions, cosmetic or functional purposes, and re-excisions were excluded. The number needed to biopsy (NNB) was calculated as the number of biopsied lesions divided by histologically proven skin cancers.


The NNB by clinician type was 2.82 for dermatology physicians, 4.69 for APPs, 4.55 for nondermatology PCPs, and 6.55 for other nondermatology clinicians (P  < .001). The NNB was significant between clinician groups for nonmelanoma skin cancer (dermatology physicians, 2.00; APPs, 2.71; PCPs, 2.36; and other nondermatology clinicians, 3.47; P  < .001) but not for melanoma (dermatology clinicians, 14.33; APPs, 20.78; PCPs, 27.80; and other nondermatology clinicians, 53.56; P  = .061).


The NNB represents a measure of use but gives no insight into the number of malignant lesions that go unbiopsied and, therefore, undiagnosed. The prevalence of skin cancer varies among dermatology and nondermatology practices. The results are not generalizable to all practice settings.


Dermatology physicians had the lowest NNB of all clinician groups. PCPs performed similarly to dermatology APPs.

The full text of this article is available in PDF format.

Key words : biopsy use, number needed to biopsy, primary care physicians, skin cancer

Abbreviations used : APP, CI, NMSC, NNB, PCP

 Drs Bennett and Xu contributed equally to this article.
 Funding sources: None.
 Conflicts of interest: None disclosed.

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