Frozen sections can spare patients from second procedures
The findings suggest a role for frozen section to help to determine whether a unilateral or bilateral simultaneous TAB should be performed, the study authors noted.
“If the frozen section is positive on the first TAB, a contralateral TAB is deferred, given the very low false-positive rate (0.6%). However, if the frozen section does not align with the permanent section result, in particular if the frozen section is positive but permanent section is negative, the patient returns for a TAB on the contralateral side if the GCA suspicion remains high,” they said.
The use of frozen sections requires ideal conditions in order to be effective, Dr. Chévez-Barrios said. The Mayo Clinic approach “is only possible because of their appropriate hospital setting, the training of the histotechnologists, and the experience of the pathologists interpreting the stains and sections. For most pathology laboratories outside of the Mayo Clinic, frozen sections on arteries are the exception and are used only in specific scenarios.”
In addition, the American College of Rheumatology recommends that patients with a high suspicion of GCA should begin corticosteroids as soon as laboratory studies are obtained; “As a result, if a TAB is performed after treatment begins, the typical active pattern of inflammation in the artery changes,” Dr. Chévez-Barrios said. “This further challenges the diagnosis in a frozen section setting because of the need for immunohistochemistry.” Although frozen sections are feasible in specialized settings such as the Mayo Clinic, most patients receive adequate diagnosis and treatment based on permanent sections.
The study findings were limited by several factors including the use of data from patients at a single center and the unique setup of the Mayo Clinic to perform rapid processing of frozen sections, the researchers noted.
“Additionally, we acknowledge that there is controversy regarding the clinical interpretation of healed arteritis. At our institution, healed arteritis is interpreted in the context of patient clinical characteristics and radiographic findings, which may differ from other institutions and may impact the results of this study,” they said.
Overall, the results support the potential of frozen sections in guiding TAB, although “more studies with a comparative analysis of laboratory results, clinical symptoms, and patient demographic characteristics between positive and negative frozen and permanent TAB results are needed to confirm our findings,” they concluded.
The study received no outside funding. One author reported receiving grants from Eli Lilly and Kiniksa Pharmaceuticals as well as personal fees from Genentech-Roche and Sanofi. Dr. Chévez-Barrios had no financial conflicts to disclose.