Reply: Commentary on letter to the editor from Drago et al

To the Editor: We appreciate the opportunity to respond to the letter by Drago et al, regarding our recently published report, “Ibrutinib-associated pityriasis rosea-like rash.”¹

The comments raised 3 important points regarding the differentiation between classic pityriasis rosea (PR) and PR-like eruption that were not detailed in our report. Human herpes viruses (HHV) 6 and 7 have been linked to the pathogenesis of classic PR but not to PR-like eruptions.² Unfortunately, we did not evaluate our patient for the presence of HHV-6/7 serum antibodies or plasma DNA during the acute phase of the eruption.3, 4, 5, 6 Regarding peripheral eosinophilia, our patient had transient eosinophilia with absolute eosinophil count of 880. The presence of eosinophilia might support a drug-induced eruption; however, most of the PR-like eruptions present with normal eosinophil count.² Drago et al² also questioned the resolution of the eruption without discontinuation of the culprit medication. We did not advocate for discontinuation of the medication because the patient's chronic lymphocytic leukemia was responsive to ibrutinib.¹ The risk of discontinuing ibrutinib outweighed the benefit. We appreciate the comparison table that outlines the clinical, histopathologic, and virologic criteria, which can serve as a guide when evaluating patients for suspected PR or PR-like eruptions caused by a drug.⁷