Aim of the study Patients with cancer might have an increased risk for severe outcome of coronavirus disease 2019 (COVID-19). To identify risk factors associated with a worse outcome of COVID-19, a nationwide registry was developed for patients with cancer and COVID-19. Methods This observational cohort study has been designed as a quality of care registry and is executed by the Dutch Oncology COVID-19 Consortium (DOCC), a nationwide collaboration of oncology physicians in the Netherlands. A questionnaire has been developed to collect pseudonymised patient data on patients’ characteristics, cancer diagnosis, and treatment. All patients with COVID-19 and a cancer diagnosis or treatment in the past 5 years are eligible. Results Between March 27 th and May 4 th , 442 patients were registered. For this first analysis, 351 patients were included of whom 114 patients died. In multivariable analyses, age ≥65 years ( p <0.001), male gender ( p =0.035), prior or other malignancy ( p =0.045), and active diagnosis of haematological malignancy ( p =0.046) or lung cancer ( p =0.003) were independent risk factors for a fatal outcome of COVID-19. In a subgroup analysis of patients with active malignancy, the risk for a fatal outcome was mainly determined by tumour type (haematological malignancy or lung cancer) and age (≥65 years). Conclusion The findings in this registry indicate that patients with a haematological malignancy or lung cancer have an increased risk of a worse outcome of COVID-19. During the ongoing COVID-19 pandemic, these vulnerable patients should avoid exposure to SARS-CoV-2, whereas treatment adjustments and prioritizing vaccination, when available, should also be considered.

Key Clinical MessagePrimary cardiac lymphoma (PCL), a rare disease, often presents with symptoms resembling other cardiac diseases. The correct diagnosis is crucial, as cardiac lymphoma can be cured with immuno‐chemotherapy. PCL has a high risk of central nervous system recurrence (CNS); therefore, screening for CNS involvement and even prophylaxis may be necessary.

An 18-year-old negroid woman presented with progressive cramps in both hands. She was Jamaican and had moved to The Netherlands 8 months before. On physical examination Trousseau's sign was positive. Laboratory analysis showed severe hypocalcaemia (1.17 mmol/L) and hyperphosphatemia (2.0 mmol/L). Urinary excretion of both calcium (0.8 mmol/day) and phosphate (5 mmol/day) was low, as is seen in hypoparathyroidism. However, the PTH level was increased (22.1 pmol/L), whereas 25-(OH)-vitamin D was low (31 nmol/L). An Ellsworth-Howard test showed only a fivefold increase in urinary phosphate excretion after administration of synthetic PTH, supporting the diagnosis pseudohypoparathyroidism. Upon treatment with calcium supplementation and alfacalcidol, her symptoms disappeared. Pseudohypoparathyroidism (PHP) is a rare hereditary disorder resembling hypoparathyroidism, although plasma PTH levels are elevated. PHP is caused by alterations in the PTH receptor, inducing target tissue resistance to PTH. This results in hypocalcaemia and hyperphosphatemia, while PTH levels are elevated. The diagnosis is confirmed by the Ellsworth-Howard test, which will show a 100-fold increase in phosphate excretion if the PTH receptor functions properly. Treatment is lifelong supplementation of calcium and alfacalcidol. In our patient, symptoms were probably evoked by the lack of sunlight in Dutch winter, decreasing vitamin D levels and thereby aggravating hypocalcaemia.