Ibrutinib is a
Bruton tyrosine kinase inhibitor used to treat many hematologic conditions, most commonly
B-cell lymphomas and
leukemias. Reportedly,
skin rash is an adverse event in up to 27% of treated patients. Histopathologic description of these lesions is limited. We present two cases of
ibrutinib-associated skin toxicities showing diverse histopathologic features. Case 1: A 72-year-old man was started on
ibrutinib for
chronic lymphocytic leukemia. Two months later, he developed multiple erythematous crusted papules on the chest, abdomen, and extremities. Biopsies revealed varied histopathology including poorly formed granulomatous
dermatitis, epidermal
necrosis, ulceration, and
panniculitis.
Ibrutinib was discontinued and his skin lesions resolved within 1 month. Case 2: A 48-year-old man received
ibrutinib after failing standard
therapy for primary central nervous system EBV positive
diffuse large B-cell lymphoma. Two months after initiation of
ibrutinib, he developed multiple firm, red, non-tender nodules on the forehead, buttock, and thigh. Biopsies revealed "
pseudolymphoma"-like reaction with dense pandermal lymphohistiocytic
inflammation and
granulomas. His skin toxicity resolved without cessation of
therapy. Awareness of the spectrum of histopathologic features that may be encountered in skin lesions of patients treated with
ibrutinib, as illustrated by these two cases, will be critical for optimal patient management.