Background Patients with a penicillin allergy label tend to have worse clinical outcomes and increased healthcare use. Drug provocation tests (DPT) are the gold‐standard in the diagnostic workup of penicillin allergy, but safety concerns may hinder their performance. We aimed to assess the frequency of severe reactions following a DPT in patients with reported allergy to penicillins or other β‐lactams. Methods We performed a systematic review, searching MEDLINE, Scopus, and Web of Science. We included primary studies assessing participants with a penicillin allergy label who underwent a DPT. We performed a Bayesian meta‐analysis to estimate the pooled frequency of severe reactions to penicillin DPTs. Sources of heterogeneity were explored by subgroup and metaregression analyses. Results We included 112 primary studies which included a total of 26,595 participants. The pooled frequency of severe reactions was estimated at 0.06% (95% credible interval [95% CrI] = 0.01%–0.13%; I2 = 57.9%). Most severe reactions (80/93; 86.0%) consisted of anaphylaxis. Compared to studies where the index reaction was immediate, we observed a lower frequency of severe reactions for studies assessing non‐immediate index reactions (OR = 0.05; 95% CrI = 0‐0.31). Patients reporting anaphylaxis as their index reaction were found to be at increased risk of developing severe reactions (OR = 13.5; 95% CrI = 7.7–21.5; I2 = 0.3%). Performance of direct DPTs in low‐risk patients or testing with the suspected culprit drug were not associated with clinically relevant increased risk of severe reactions. Conclusions In patients with a penicillin allergy label, severe reactions resulting from DPTs are rare. Therefore, except for patients with potentially life‐threatening index reactions or patients with positive skin tests—who were mostly not assessed in this analysis ‐, the safety of DPTs supports their performance in the diagnostic assessment of penicillin allergy.

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Within our cohort, radiation cystitis is an uncommon complication of prostatic radiotherapy treatment, and severe cases requiring hospitalization are even more infrequent. We found no association between tumor characteristics, radiotherapy setting or radiation dose and the cumulative incidence of radiation cystitis.

Angiomatoid Spitz nevus is a rare tumor that combines the classic aspects of Spitz nevus with a prominent vascular component. Clinically, it presents as a pink or brownish papule, usually solitary, in the extremities of young adults. On histology, it is characterized by a proliferation of epithelioid or spindle cell melanocytes embedded in a fibrous stroma, where a dense proliferation of small vessels is evident. The differential diagnosis with malignant melanoma can be difficult, particularly with the desmoplastic variant or with those with marked regression. Its behavior is benign, as suggested by the absence of local recurrences or distant metastases during long-term follow-up.