Cancer-associated thrombotic microangiopathy is a group of disorders defined by microvascular thrombosis, thrombocytopoenia and ischaemic end-organ damage. Rarely, it may be a manifestation of the malignancy itself or a side effect of its therapy.

We report on a 64-year-old male, diagnosed in 2017 with a T1N1M0 squamous cell carcinoma of the pyriform sinus treated by radio-chemotherapy (cisplatin + 70 Gy). The patient was hospitalised six months after the completion of the treatment, while he was still in complete remission, for fatigue and an altered general status. Laboratory results revealed haemolytic anaemia, thrombocytopenia, a negative coombs test, LDH 537, undetectable haptoglobin and acute renal insufficiency requiring haemodialysis. Investigations showed presence of schistocytes, a normal ADAMTS13 activity and absence of ADAMTS13 inhibition. A kidney biopsy confirmed the diagnosis of thrombotic microangiopathy and plasmapheresis was initiated which lead to a partial resolution of the thrombocytopenia and other microangiopathy factors. A PET-CT scan revealed multiple secondary lesions in the lungs along with the lymph nodes. A lymph node biopsy was performed and showed metastatic squamous cell carcinoma which confirmed the probable paraneoplastic nature of the disease. We conducted a literature review that revealed that when the thrombotic microangiopathy is cancer-associated it is necessary to treat the underlying disease. It was therefore decided to discontinue the plasmapheresis and treat with anti-PD1 antibody therapy (nivolumab). A PET-scan revealed progression after three cycles of nivolumab and we decided to stop the treatment, however we did not observe recurrence of the thrombotic microangiopathy.

Despite the debate about immunotherapy in active autoimmune diseases, this case demonstrates the safety of anti PD-1 therapy in case of a paraneoplastic immune disease.