Population-Based Analysis of Histologically Confirmed Melanocytic Proliferations Using Natural Language Processing.

Importance: Population-based information on the distribution of histologic diagnoses associated with skin biopsies is unknown. Electronic medical records (EMRs) enable automated extraction of pathology report data to improve our epidemiologic understanding of skin biopsy outcomes, specifically those of melanocytic origin. Objective: To determine population-based frequencies and distribution of histologically confirmed melanocytic lesions. Design, Setting, and Participants: A natural language processing (NLP)-based analysis of EMR pathology reports of adult patients who underwent skin biopsies at a large integrated health care delivery system in the US Pacific Northwest from January 1, 2007, through December 31, 2012. Exposures: Skin biopsy procedure. Main Outcomes and Measures: The primary outcome was histopathologic diagnosis, obtained using an NLP-based system to process EMR pathology reports. We determined the percentage of diagnoses classified as melanocytic vs nonmelanocytic lesions. Diagnoses classified as melanocytic were further subclassified using the Melanocytic Pathology Assessment Tool and Hierarchy for Diagnosis (MPATH-Dx) reporting schema into the following categories: class I (nevi and other benign proliferations such as mildly dysplastic lesions typically requiring no further treatment), class II (moderately dysplastic and other low-risk lesions that may merit narrow reexcision with <5-mm margins), class III (eg, melanoma in situ and other higher-risk lesions warranting reexcision with 5-mm to 1-cm margins), and class IV/V (invasive melanoma requiring wide reexcision with ≥1-cm margins and potential adjunctive therapy). Health system cancer registry data were used to define the percentage of invasive melanoma cases within MPATH-Dx class IV (stage T1a) vs V (≥stage T1b). Results: A total of 80 368 skin biopsies, performed on 47 529 patients, were examined. Nearly 1 in 4 skin biopsies were of melanocytic lesions (23%; n = 18 715), which were distributed according to MPATH-Dx categories as follows: class I, 83.1% (n = 15 558); class II, 8.3% (n = 1548); class III, 4.5% (n = 842); class IV, 2.2% (n = 405); and class V, 1.9% (n = 362). Conclusions and Relevance: Approximately one-quarter of skin biopsies resulted in diagnoses of melanocytic proliferations. These data provide the first population-based estimates across the spectrum of melanocytic lesions ranging from benign through dysplastic to malignant. These results may serve as a foundation for future research seeking to understand the epidemiology of melanocytic proliferations and optimization of skin biopsy utilization.