Dual checkpoint inhibitor therapy has known immune-related adverse events. However, checkpoint inhibitor-associated thrombotic thrombocytopenic purpura is very rarely reported. We present a case of a 70-year old man with advanced melanoma, presenting with severe thrombocytopenia, hemolytic anemia with schistocytes and suppressed ADAMTS-13 activity by ADAMTS-13 inhibitors. We discuss differential diagnoses and speculated mechanisms of this obviously therapy-related adverse event, which should be considered by clinicians prescribing these drugs.

AIMS OF THE STUDY: To investigate the prevalence of hypercalcemia (>2.60 mmol/l) and severe hypercalcemia (≥2.80 mmol/l) on admission. Symptoms, causes, course of serum calcium, treatment and outcome of severe hypercalcemia were evaluated and compared to historical data from previous studies. METHODS: In this retrospective cohort study, all patients presenting to the interdisciplinary emergency department of the Buergerspital Solothurn between 01 January 2017 and 31 December 2020 with measurements of serum calcium were included. Chart reviews were performed for patients with calcium ≥2.80 mmol/l to assess clinical presentation, course of disease and treatment for severe hypercalcemia. RESULTS: Of 31,963 tested patients, 869 patients (2.7%) had hypercalcemia on the admission, of which 161 had severe hypercalcemia. Non-albumin corrected calcium was 3.07 (0.32) while albumin corrected calcium was 3.34 (0.44). Calcium was higher in patients with malignancy-related hypercalcemia (3.18 [0.34] versus 3.00 [0.3], p <0.001). Neuropsychiatric (35%) and gastrointestinal (24%) were the leading symptoms. Malignancy was the most common identifiable cause of hypercalcemia (40%), with lung cancer (20%), multiple myeloma (14%) and renal cell carcinoma (11%) being the main cancer types. 36% of patients with severe hypercalcemia took calcium supplements. Bisphosphonate treatment was an independent predictor of a fall in calcium until day 5 (regression coefficient: –0.404, standard error 0.11, p <0.001). Hypercalcemia was not mentioned in the final discharge report in 38% of cases. CONCLUSION: Severe hypercalcemia is common and malignancy-related in almost half of the cases. Neuropsychiatric and gastrointestinal symptoms were most prevalent. Awareness of hypercalcemia, particularly in cancer patients and those with known triggering factors, should be raised in order to identify and treat this harmful disorder early.

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