COVID-19-Associated Erythema Nodosum Detected on FDG PET/CT

We report the case of a 69-year-old woman who underwent 18F-FDG PET/CT due to prolonged fever. One month before, the patient was diagnosed with COVID-19 infection. The 18F-FDG PET/CT showed several subcutaneous nodules with 18F-FDG uptake on the thorax and upper extremities and bilateral lung infiltrates due to organizing pneumonitis. Clinical examination revealed multiple tender nodules on thorax, arms, and legs, consistent with erythema nodosum (EN) induced by COVID-19 infection. The woman was treated with prednisone with a good effect on EN. To our knowledge, this is the first report on EN secondary to COVID-19 infection diagnosed on 18F-FDG PET/CT.

Automated summary

We present a case of a 69-year-old female with prolonged fever who underwent 18F-FDG PET/CT. The scan revealed subcutaneous nodules with increased 18F-FDG uptake on the thorax and upper extremities, as well as bilateral lung infiltrates due to organizing pneumonitis. Clinical examination confirmed erythema nodosum induced by COVID-19 infection. Prednisone treatment resulted in improvement of the erythema nodosum. This is the first report of COVID-19-induced erythema nodosum diagnosed on 18F-FDG PET/CT.