ABSTRACT
ATC is a rare cancer with a slightly growing incidence and a poor prognosis determined by the delay of treatment, usually revealed by an enlarging goiter with compressive symptoms and, more rarely, by inflammatory and thyrotoxic symptoms, a clinic entity called malignant pseudothyroiditis (MPT) mimicking subacute thyroiditis (SAT). With the advent of COVID-19 pandemic, many cases of COVID-19 related SAT were described with the usual clinical presentation enriched by the COVID-19 symptoms, leading to the emergence of atypic clinical pictures. We present the case of a 60-year-old patient who developed, one month after a COVID 19 acute infection, a clinical presentation of SAT with atypical ultrasound features leading to the diagnosis of MPT; histological atypia was misleading, finally making precise diagnosis was difficult. To our best knowledge, this is the first ever reported case of MPT mimicking COVID-19 SAT. We reviewed thirty five cases published to date and discuss the mechanisms underlying MPT physiopathogenesis and the ultrasound and histological features. We point out the similarities between MPT and SAT and the role of ultrasound at clinical presentation workup. Finally there are two key points to remind: First, to perform neck ultrasound in any painful goiter and, in case of atypia, perform a US guided core-needle biopsy, a complementary CT-scan and quickly refer the patient to an expert center. Second, always think that COVID-19 infection is a recent entity and be aware that it can influence the clinical presentation of any disease.