Cancer is not a risk factor for severe COVID-19 in children, except in patients with recent allogeneic hematopoietic stem cell transplantation or comorbidities.

The EPICO (Spanish general registry of COVID-19 in children)-SEHOP (Spanish Society of Pediatric Hematology and Oncology) platform gathers data from children with SARS-CoV-2 in Spain, allowing comparison between children with cancer or allogeneic hematopoietic stem cell transplantation (alloHSCT) and those without. The infection is milder in the cancer/alloHSCT group than in children without comorbidities (7.1% vs. 14.7%), except in children with recent alloHSCT (less than 300 days), of which 35.7% experienced severe COVID-19. These data have been shared with the SEHOP members to support treatment and isolation policies akin to those for children without cancer, except for those with recent alloHSCT or additional comorbidities. This highlights the collaborative registries potential in managing pandemic emergencies.

Metastatic pulmonary dissemination as differential diagnosis of COVID-19 disease.

A 13-year-old boy presented to hospital with 3-day self-limited fever, followed by dry cough, persistent asthenia and impaired general condition of 2 weeks' duration. Blood analyses showed a severe inflammatory status and chest X-ray images were consistent with bilateral COVID-19 pneumonia. He developed an acute respiratory failure that required paediatric intensive care admission and non-invasive ventilation. A targeted COVID-19 treatment was initiated with hydroxicloroquine, corticosteroids, enoxaparine and a single dose of tocilizumab. Repeated serological tests and real-time reverse transcription PCR for SARS-CoV-2 were negative. Other infectious pathogens were also ruled out. Thoracic high resolution CT showed an intense bilateral pulmonary dissemination with lytic vertebral bone lesions. After diagnostic investigations, Ewing's sarcoma with metastatic pulmonary dissemination was diagnosed. Nowadays, in the context of SARS-CoV-2 community pandemic, we cannot forget that COVID-19 clinical presentation is not specific and other entities can mimic its clinical features.