The effectiveness and safety of skin biopsy for patients with suspected calciphylaxis were described in study data published in the Journal of the American Academy of Dermatology. Estimated sensitivity of initial biopsy was 51.8%, suggesting that providers should carefully consider patient health status and likelihood of calciphylaxis before sampling.

Investigators conducted a retrospective study of patients with calciphylaxis who underwent biopsy at hospitals in Boston, Massachusetts from 2006 to 2018. Patients were included in analyses if they had a clinical diagnosis of calciphylaxis and underwent skin biopsy to evaluate for calciphylaxis. Patients with an indeterminate or negative biopsy were excluded. Multivariate logistic regression was performed to identify correlates of confirmatory biopsy.

The study cohort comprised 114 patients who collectively underwent 233 biopsies. The majority of patients were women (74.0%), White (70.2%), and ≥50 years of age (82.4%). Overall, 86.8% of patients eventually had a biopsy which confirmed diagnosis. Initial biopsy sensitivity was 51.8%. Median number of biopsies per patient was 2 (range, 1-9); median diagnostic delay was 71 days (range, 0-496). Confirmatory biopsy led to therapy change in 50.5% of patients. Biopsy location was significantly associated with sensitivity: biopsy at the distal leg was more likely to be confirmatory than biopsy at the proximal leg (odds ratio [OR], 2.78; 95% confidence interval [CI], 1.46-5.31; P =.002). Sensitivity improved with each repeat biopsy encounter (OR, 1.99; 95% CI, 1.20-3.30; P =.007). Biopsy size and type were not significantly associated with sensitivity. Biopsy complications were observed in 16 patients (14.0%), including site-specific necrosis and poor biopsy site healing. Nine of these complications occurred from biopsies sampled below the knee. One patient developed necrotizing fasciitis after biopsy and died from associated complications.

Given the low initial sensitivity of skin biopsies for calciphylaxis, study authors recommended that providers “consider pre-test probability and health status of a patient…prior to decision to biopsy.” Tissue should be sampled conservatively to minimize complications. Further study is necessary to identify other diagnostic modalities for calciphylaxis.


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Reference

Dobry AS, Nguyen ED, Shah R, Mihm MC, Kroshinsky D. The role of skin biopsy in diagnosis and management of calciphylaxis: a retrospective analysis [published online May 29, 2020]. J Am Acad Dermatol. doi: 10.1016/j.jaad.2020.05.101