The Covid-19 pandemic has created exceptional challenges for patients and medical care systems. Among many factors influencing postponed cancer diagnosis, mask-wearing created difficulties in initial diagnosis of head and neck tumours. This report features a patient who had been covering a submandibular tumour under a surgical mask for more than 6 months. He visited his general practitioner due to a significant weight loss, but he neither took his mask off, nor was he asked to do so. When he reported to our emergency room, we noticed a massive ulcerous mass in the right submandibular region. Histological examination confirmed primary squamocellular carcinoma of submandibular salivary gland. During the Covid-19 pandemic, significant clinical observations may be missed if a surgical mask or respirator are not removed during examination with the potential for increased incidence of medical malpractice claims.