Scoping Review Highlights Diagnostic Value of Direct Immunofluorescence in Cutaneous Vasculitis

For this purpose, the researchers searched two electronic databases for articles on direct immunofluorescence (DIF) and vasculitis, covering the period from January 1975 to October 2023. They included relevant case series featuring three or more patients, published in English, and available in full text. Additional articles were identified through manual reference review. Given the heterogeneity of the studies, the findings were analyzed descriptively.

The key findings were as follows:

• Out of 255 articles identified, 61 met the inclusion criteria, collectively representing over 1,000 DIF specimens.
• Several studies estimated the sensitivity of DIF to be around 75%.
• Vascular immunoglobulin A (IgA) deposits identified by DIF were linked to renal disease, while other systemic associations varied.
• Vascular IgG deposition may be more prevalent in ANCA-associated vasculitis.
• The presence of granular vascular and epidermal basement membrane zone immunoglobulin deposition was able to differentiate between hypocomplementemic and normocomplementemic urticarial vasculitis. However, few studies have explored the added value of DIF compared to routine microscopy alone in vasculitis.

"The use of DIF testing, along with biopsy and hematoxylin and eosin staining, continues to be a cornerstone of the gold standard work-up for diagnosing vasculitis. This is particularly true for IgA vasculitis, where IgA deposits are closely linked to an increased risk of renal disease," the researchers wrote.

"Further studies are needed to compare the sensitivity of DIF testing with that of histopathology," they concluded.

Reference:

Lehman JS, Ferringer TC, Fung MA, Cassarino DS, Shalin SC. Diagnostic utility of direct immunofluorescence test panels for cutaneous vasculitis: A scoping review. J Cutan Pathol. 2024 Sep 22. doi: 10.1111/cup.14722. Epub ahead of print. PMID: 39307568.