Variable loss of CD30 expression by immunohistochemistry in recurrent cutaneous CD30+ lymphoid neoplasms treated with brentuximab vedotin.

This case series highlights the finding that CD30 positivity can be variable in recurrences after treatment with anti-CD30 antibodies. This serves to raise awareness of the phenomenon of antigen loss after treatment with brentuximab vedotin and underscores the utility of performing multiple biopsies and/or employing molecular diagnostic techniques in patients with recurrent/persistent disease.