Fung, Maxwell A.

ImportanceDirect immunofluorescence (DIF) testing has been an important ancillary tool for the diagnosis of various inflammatory mucocutaneous conditions for more than 50 years. Current DIF test panels are based on historical clinical descriptions; few studies have rigorously addressed preanalytical, analytical, and/or postanalytical aspects, and even fewer have been replicated or validated. Recent unresolved key issues include whether DIF testing and test panels should be triaged or truncated based on clinical indication or histopathologic findings.ObjectiveTo assess levels of consensus regarding practical aspects of DIF testing among immunodermatology testing specialists in the US.Design, Setting, and ParticipantsUsing modified Delphi methods with a priori characterized criteria, a survey containing 54 statements pertaining to DIF testing was created and distributed to assess consensus. Statements not initially reaching consensus were discussed in 2 live virtual sessions, which were supplemented by relevant literature review and free-text survey comments. These statements were then reassessed in a second survey. Immunodermatology testing specialists in US academic institution–based and independent laboratories were invited based on serving as immunodermatology laboratory medical directors, authoring pertinent literature, or delivering relevant talks at major conferences or by referral. The first survey was conducted from January to February 2024, and the second survey was conducted from March to April 2024.Main Outcomes and MeasuresThe primary measured outcome was degree of consensus for various DIF testing practice, including DIF testing triage by histopathology/dermatopathology findings and DIF testing panel tailored truncations by clinical indication.ResultsA total of 23 respondents to the survey invitation had a mean (SD) of 18.5 (11.1) years and median (range) of 20.0 (1.5-46.0) years in immunodermatology laboratory practice. Consensus was achieved for 46 of 54 statements (85.2%) in the initial survey and for an additional 4 statements in the second survey (50 of 54 [92.6%]). Strong consensus was found against tailored truncation of DIF panel based on the clinical indication in the first survey round. The general acceptability of triaging specimens for DIF testing based on histopathology findings remained without consensus after both surveys.Conclusions and RelevanceOverall, participating US specialists in immunodermatology laboratory testing agreed on many practical aspects of DIF testing, including matters not queried previously. The findings also revealed areas of continued controversy and identified issues for prioritized future study.

AbstractBackgroundDue to the immune‐mediated nature of non‐infectious cutaneous vasculitis, skin biopsy specimens are often submitted for direct immunofluorescence (DIF) testing when vasculitis is considered clinically. However, evidence regarding the clinical value of DIF has not been rigorously appraised.ObjectiveIn this scoping review, we aimed to systematically evaluate the peer‐reviewed literature on the utility of DIF in vasculitis to assist with the development of appropriate use criteria by the American Society of Dermatopathology.MethodsTwo electronic databases were searched for articles on DIF and vasculitis (January 1975–October 2023). Relevant case series involving more than or equal to three patients, published in English, and with full‐text availability were included. Additional articles were identified manually via reference review. Due to study heterogeneity, findings were analyzed descriptively.ResultsOf 255 articles identified, 61 met the inclusion criteria. Cumulatively representing over 1000 DIF specimens, several studies estimated DIF sensitivity to be 75%. While vascular immunoglobulin A (IgA) deposits on DIF were associated with renal disease, other systemic associations were inconsistent. Vascular IgG deposition may be overrepresented in ANCA‐associated vasculitis. Granular vascular and epidermal basement membrane zone Ig deposition differentiated hypocomplementemic from normocomplementemic urticarial vasculitis. Few studies have assessed the added value of DIF over routine microscopy alone in vasculitis.ConclusionsThis scoping review discovered that DIF testing for vasculitis has been performed not only for diagnostic confirmation of vasculitis but also for disease subtype classification and prediction of systemic associations. Future studies on test sensitivity of DIF compared to that of histopathology are needed.

AbstractBackgroundAppropriate use criteria (AUC) provide patient‐centered physician guidance in test selection. An initial set of AUC was reported by the American Society of Dermatopathology (ASDP) in 2018. AUC reflect evidence collected at single timepoints and may be affected by evolving evidence and experience. The objective of this study was to update and expand AUC for selected tests.MethodsRAND/UCLA (RAND Corporation [Santa Monica, CA]/University of California Los Angeles) methodology used includes the following: (a) literature review; (b) review of previously rated tests and previously employed clinical scenarios; (c) selection of previously rated tests for new ratings; (d) development of new clinical scenarios; (e) selection of additional tests; (f) three rating rounds with feedback and group discussion after rounds 1 and 2.ResultsFor 220 clinical scenarios comprising lymphoproliferative (light chain clonality), melanocytic (comparative genomic hybridization, fluorescence in situ hybridization, reverse transcription polymerase chain reaction, telomerase reverse transcriptase promoter), vascular disorders (MYC), and inflammatory dermatoses (periodic acid‐Schiff, Gömöri methenamine silver), consensus by panel raters was reached in 172 of 220 (78%) scenarios, with 103 of 148 (70%) rated “usually appropriate” or “rarely appropriate” and 45 of 148 (30%), “appropriateness uncertain.” Limitations: The study design only measures appropriateness. Cost, availability, test comparison, and additional clinical considerations are not measured. The possibility that the findings of this study may be influenced by the inherent biases of the dermatopathologists involved in the study cannot be excluded.ConclusionsAUC are reported for selected diagnostic tests in clinical scenarios that occur in dermatopathology practice. Adhering to AUC may reduce inappropriate test utilization and improve healthcare delivery.

BackgroundAppropriate use criteria (AUC) provide physicians guidance in test selection, and can affect health care delivery, reimbursement policy and physician decision‐making.ObjectivesThe American Society of Dermatopathology, with input from the American Academy of Dermatology and the College of American Pathologists, sought to develop AUC in dermatopathology.MethodsThe RAND/UCLA appropriateness methodology, which combines evidence‐based medicine, clinical experience and expert judgment, was used to develop AUC in dermatopathology.ResultsWith the number of ratings predetermined at 3, AUC were developed for 211 clinical scenarios involving 12 ancillary studies. Consensus was reached for 188 (89%) clinical scenarios, with 93 (44%) considered “usually appropriate,” 52 (25%) “rarely appropriate” and 43 (20%) “uncertain appropriateness.”LimitationsThe methodology requires a focus on appropriateness without comparison between tests and irrespective of cost.ConclusionsThe ultimate decision of when to order specific test rests with the physician and is one where the expected benefit exceeds the negative consequences. This publication outlines the recommendations of appropriateness—AUC for 12 tests used in dermatopathology. Importantly, these recommendations may change considering new evidence. Results deemed “uncertain appropriateness” and where consensus was not reached may benefit from further research.