Reply to the letter by Law et al. Is Rituximab therapy in Castleman’s disease a risk factor for Kaposi sarcoma reactivation?

Excerpt

The unusual case reported by Law AB and co. underlines the complex (and largely unknown) interplay occurring between HHV8 infection, MCD, KS and Rituximab treatment [1]. The clinical course of the patient is more similar to what we usually observe in MCD HIV-positive patients treated with Rituximab than in MCD HIV-negative cases. Of the nine HIV-negative MCD cases treated with Rituximab-based chemotherapy or Rituximab-alone reported in literature, only one (the present case) showed KS reactivation with an abrupt onset and an aggressive clinical course. However, the occurrence of such event is not entirely surprising considering that both HHV8-positive MCDs and KS, outside of HIV-positive cohort, mostly occur in elderly people believed to have some “criptic” form of immunosuppression. In this context, the B cell depletion induced by Rituximab could represent a doubled-edged sword: the benefit obtained by inducing MCD remission may be offset by a reduced immunosurveillance against cancer or other infectious agents. …