Test Utilization in Dermatopathology: Recent Study Offers Appropriate-Use Criteria for 12 Diagnostic Tests, Focusing on Quality of Patient Care, Safety, and Cost

The exponential increase in the number of diagnostic tests available to physicians (in dermatopathology as well as other medical specialties) can be overwhelming, according to a new multi-institutional study co-published in the Journal of Cutaneous Pathology and Journal of the American Academy of Dermatology entitled “Appropriate Use Criteria in Dermatopathology: Initial Recommendations by the American Society of Dermatopathology.”1,2 Dermatopathology is a subspecialty of dermatology and surgical pathology where dermatopathologists analyze patient tissue specimens under a microscope to arrive at diagnoses. They also research possible causes of hair, nail, and skin disorders at the cellular level.

First-of-Its-Kind Study 

Mayo Clinic is one of many institutions that participated in the study with an emphasis on how best to guide health care providers when ordering these types of tests. The researchers focused on test-utilization methods that would provide high value to the providers and their patients.

Claudia Vidal, M.D., Ph.D., lead author of the study, says, “Given the increase in cost from new technologies, physicians need tools to help them make decisions about health care, especially in appropriateness of care that can achieve meaningful outcomes, increase the quality of patient care, and control medical costs.”

This study is the first of its kind in the field of pathology and is the vision of former American Society of Dermatopathology President Dirk Elston, M.D. Utilizing the RAND/ UCLA appropriateness methodology, which takes into account available scientific evidence and expert consensus, the Appropriate-Use Criteria (AUC) Committee for the American Society of Dermatopathology, chaired by M. Yadira Hurley, M.D., sought to develop guidelines for 211 clinical scenarios involving 12 ancillary tests used in dermatopathology. The guidelines are meant to help physicians make more informed decisions in their practice.

Front row, L to R: M. Yadira Hurley, M.D., and Alexandra Hristov, M.D.
Second row, L to R: Lori Lowe, M.D.; Victor Prieto, M.D., Ph.D.; Claudia Vidal, M.D., Ph.D.; Patricia Missall, M.D., Ph.D.; Gregory Hosler, M.D., Ph.D.; and Uma Sundram, M.D., Ph.D.
Last row, L to R: Maxwell Fung, M.D.; Patrick Emanuel, M.B., Ch.B.; Konstantinos Linos, M.D.; Aleodor Andea, M.D.; Brandon Litzner, M.D.; and Lyn Duncan, M.D.

Challenges with Increasing Number of Tests Available

Nneka Comfere, M.D.

“As medicine advances, we are seeing an increasing number of diagnostic tests with specific applications in various clinical settings and nuances in their interpretation,” says Nneka Comfere, M.D., Division Chair, Dermatopathology and Cutaneous Immunopathology, within Mayo’s Department of Dermatology, who co-authored the study. “This has resulted in challenges with test selection—and interpretation—that guide medical decision-making in the practice.”

According Dr. Comfere, health care providers need to “move away from reflexive diagnostic test ordering to a systematic approach” that takes into account the clinical scenario and test characteristics, including its pretest probability, to apply the appropriate test for the specific situation.

When a physician considers a specific test for a specific patient, there can be more than one correct choice, in which case, a variety of factors must be considered. The list includes understanding the test’s characteristics, the clinician’s expertise with test interpretation, accessibility of the test, insurance coverage, cost of the test, and patient preference.

Guidelines for Navigating Complex Waters

“This study offers guidance in test utilization to clinicians who order and interpret results for 12 diagnostic tests that are frequently used in dermatopathology,” says Dr. Comfere. “There is wide variation in the use of these tests in the practice for the selected clinical scenarios. This study attempts to qualify the appropriateness of each of the 12 diagnostic tests that were evaluated for those commonly encountered clinical scenarios.”

The 211 clinical scenarios were identified and are broken down into four broad diagnostic categories, covering the 12 tests:


  • T-cell receptor (TCR) clonality assay for the beta chain by polymerase chain reaction (PCR)
  • TCR clonality assay for the gamma chain by PCR
  • B-cell receptor immunoglobulin heavy chain (IgH) clonality assay by PCR


  • fluorescence in situ hybridization (FISH)
  • comparative genomic hybridization
  • gene-expression profiling by quantitative reverse transcription polymerase chain reaction (qRT-PCR)

Soft Tissue

  • t(17;22) COL1A1-PDGFB FISH assay in the diagnosis of dermatofibrosarcoma protuberans
  • dual-color break-apart EWSR1 FISH assay in differentiating melanocytic tumors and clear cell sarcoma


  • human papilloma virus (HPV) in situ hybridization
  • HPV immunohistochemistry
  • mismatch repair (MMR) protein IHC 4 antibody panel
  • MMR IHC 2 antibody panel in the screening for Muir-Torre syndrome

Results from the study show consensus was reached by field experts for 188 (89%) of the clinical scenarios, with 93 (44%) considered “usually appropriate,” 52 (25%) “rarely appropriate,” and 43 (20%) “uncertain appropriateness.”

A clinician faced with a patient who has been diagnosed with a disease that falls within one of the four diagnostic subgroups and is considering ordering one of these tests now has “guidance regarding the level of appropriateness of the test for that scenario,” says Dr. Comfere. “Tests with an uncertain level of appropriateness are those that had insufficient evidence for assessment.”

Quality, Efficiency, and Safer Patient Care

Key elements of high-value health care include clinical outcomes, safety, patient experience, and cost. So, how do the results of this effort address these elements?

“The recommendations of this study are based on the existing best evidence in the literature and the judgment of physicians with expertise in the identified clinical areas,” says Dr. Comfere. “With the application of these criteria in practice, we hope to begin to narrow practice variation in test utilization.”

Nneka Comfere, M.D.

The impact of these criteria applied in practice is significant, considering these tests are often considered for ordering with commonly encountered clinical scenarios. Inappropriate test utilization has implications for further downstream tests and procedures, with attendant waste and unnecessary medical services.

“If we can consistently apply a systematic approach to test selection and interpretation in specific clinical situations, then we have the opportunity to deliver higher quality and safe care to our patients,” says Dr. Comfere.

Keeping AUC in Perspective

In light of the guidance provided by these new AUC recommendations to physicians in their daily practice, the unique needs of the patient should be kept in mind while using them.

“It should be emphasized that this study may not apply to every single clinical situation,” says Dr. Comfere. “Because at the end of the day, we must consider the specific needs of each patient. Ultimately, it’s truly up to the physicians and their patients to make the best decisions regarding diagnostic test selection and interpretation for the clinical questions at hand.”


  1. Vidal CI, Armbrect EA, Andea AA, et al. Appropriate use criteria in dermatopathology: Initial recommendations from the American Society of Dermatopathology. J Cutan Pathol. 2018 Aug;45(8):563-580. doi: 10.1111/cup.13142.
  2. Vidal CI, Armbrect EA, Andea AA, et al. Appropriate use criteria in dermatopathology: Initial recommendations from the American Society of Dermatopathology. J Am Acad Dermatol. 2018 Apr 21. [Epub ahead of print]

The developed appropriate-use criteria are the work of the American Society of Dermatopathology.

Chris Bahnsen

Chris J. Bahnsen covers emerging research and discovery for Mayo Clinic Laboratories. His writing has also appeared in The New York Times, Los Angeles Times, and Smithsonian Air & Space. He divides his time between Southern California and Northwest Ohio.