Pityriasis Rosea and Immunosuppressive Drugs [Letter]

Dear editor

We read with great interest the paper of Wu et al about a case of persistent pityriasis rosea (PPR) successfully treated by a short course of therapy with abrocitinib¹ that allows us to make a few observations. The authors diagnosed the patient’s eruption as PPR but, though Auspitz sign was negative, the possibility of a psoriasiform eruption should be considered in the differential diagnosis. Indeed, the Auspitz sign is not always present in psoriasis, especially in eruptive psoriasis (guttate form). In eruptive psoriasis the papillae containing dilated and tortuous capillaries into an edematous papillary dermis, the basis of Auspitz sign,² are not as elongated and prominent. Unfortunately, no histopathology was done. The authors did not mention the presence of systemic symptoms prior to or associated with the eruption, nor the presence of the typical herald patch or oral lesions in their patient.^3,4 Having this data would have been very important since the patients affected by PPR complained frequently of systemic symptoms during the disease. Fatigue was the most common symptom and other ones included headache, insomnia, irritability and difficulty concentrating. In addition, oral lesions are present in about 75% of patients with PPR, namely strawberry tongue, erythematous macules, vesicular lesions and petechiae.^4,5 Furthermore, the authors did not perform the search for signs of human herpesvirus 6 (HHV-6) and/or human herpesvirus 7 (HHV-7) reactivation in the blood or tissues which would have been very helpful for the definitive diagnosis of PPR.^3–5 The persistence of the eruption and symptoms in PPR can be explained by the corresponding persistence of systemic HHV-6 and/or HHV-7 reactivation. Naturally, the importance of a definite diagnosis of PPR is crucial in judging therapeutic success with abrocitinib and before considering it as a hypothetical option for patients with PPR. Abrocitinib is a selective JAK1 inhibitor approved for atopic dermatitis which has also proven effective in treating eruptive psoriasis, like other drugs targeting the JAK/STAT pathway.⁶ Several herpes virus infections, namely herpes simplex and varicella-zoster infections, were reported in patients treated with abrocitinib as well as cases of eczema herpeticum.⁷ Therefore, we think that in a herpetic reactivation disease such as PPR, caution is due before extending the use of abrocitinib in its treatment.