title: The Case of a Zebra That Was Misdiagnosed as a Horse: Pulmonary Tumor Thrombotic Microangiopathy, a New Paraneoplastic Syndrome, Mimicking PD-1-Induced Pneumonitis.
abstract: A case report of a 47-year-old woman with triple-negative breast cancer on a clinical trial called PRIMETIME (NCT02518958) who received the anti-PD-1 inhibitor nivolumab and the experimental anticancer agent RRx-001 is presented. Although initially diagnosed and treated for anti-PD-1-induced pneumonitis, clinical and radiological abnormalities triggered further investigation, leading to the diagnosis of pulmonary tumor thrombotic microangiopathy (PTTM). This example highlights the importance of exercising due diligence in determining immune-related adverse events and suggests that PD-1-induced pneumonitis should be a diagnosis of exclusion rather than a diagnosis by default. A case history and review of the literature are presented for PTTM, which we propose to define as a paraneoplastic syndrome.
authors.affiliation: Walter Reed National Military Medical Center, Bethesda, Md., USA.
authors.forename: Corey A
authors.initials: CA
authors.lastname: Carter
authors.affiliation: Walter Reed National Military Medical Center, Bethesda, Md., USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Browning
authors.affiliation: EpicentRx, Mountain View, Calif., USA.
authors.forename: Bryan T
authors.initials: BT
authors.lastname: Oronsky
authors.affiliation: EpicentRx, Mountain View, Calif., USA.
authors.forename: Jan J
authors.initials: JJ
authors.lastname: Scicinski
authors.affiliation: Walter Reed National Military Medical Center, Bethesda, Md., USA.
authors.forename: Christina
authors.initials: C
authors.lastname: Brzezniak
keywords: PD-1-induced pneumonitis; Paraneoplastic syndrome; Pulmonary tumor thrombotic microangiopathy