Multicenter Evaluation of Certainty and Reliability in Calciphylaxis Diagnosis Using a Digital Imaging Platform

Area of Science:

• Dermatopathology
• Histopathology
• Medical Diagnostics

Background:

• The accuracy of calciphylaxis diagnosis relies on dermatopathologists' consistent recognition of histopathologic features and interrater reliability (IRR).
• Interpretive challenges and variability in diagnostic assessments can impact patient care for this rare condition.

Purpose of the Study:

• To quantify diagnostic challenges in calciphylaxis by evaluating pathologist certainty and IRR for histopathologic features.
• To identify which specific histopathologic features are most reliably recognized for diagnosing calciphylaxis.

Main Methods:

• An online survey was conducted with 23 dermatopathologists from 16 institutions.
• Participants reviewed clinical vignettes, photos, and digital slides (H&E and von Kossa stains) of 20 patients.
• Diagnoses and certainty in specific histopathologic features were assessed using a checklist.

Main Results:

• Diagnostic accuracy was lower for calciphylaxis (53%) than mimics (80%), with low IRR (Krippendorff alpha = 0.171 vs 0.257).
• Necrosis, finely stippled calcium, and intimal fibroplasia of pannicular arterioles differentiated calciphylaxis from mimics.
• Highest IRR was for ulceration (KA=0.66) and necrosis (KA=0.46); lowest for perieccrine calcification (KA=0.19) and intimal fibroplasia (KA=0.07).
• Pathologist confidence correlated positively with IRR for feature recognition.

Conclusions:

• Necrosis, finely stippled calcium, and intimal fibroplasia are key histopathologic features for calciphylaxis diagnosis, though IRR for intimal fibroplasia is low.
• Digital platforms enable multi-institutional studies on diagnostic concordance for rare diseases.
• Understanding pathologist confidence and IRR can inform diagnostic guidelines and medical education for calciphylaxis.