INCIDENTALLY DETECTED DIFFUSE LUNG UPTAKE ON TC-99M MIBI PARATHYROID SCAN DUE TO SMOKING-RELATED INTERSTITIAL LUNG DISEASE: FIRST CASE REPORT

Abstract

Diffuse lung uptake of Tc-99m MIBI is a rare condition on the parathyroid scan. A parathyroid scan was performed to localize parathyroid adenoma in a 42-year-old male with primary hyperparathyroidism. In dual-phase Tc-99m MIBI imaging, there was a focal persistent radiotracer uptake in the inferior aspect of the right thyroid lobe suggesting a parathyroid adenoma. In addition, unexpected diffusely increased MIBI uptake was noted in the lungs on both early and delayed images. The patient did not have a cardiac disorder and chest computed tomography (CT) was performed to investigate the underlying cause of diffuse MIBI uptake in the lungs. CT images showed ground-glass opacities (GGO) localized more prominently in the peripheral zones, pericardiac and peribronchovascular areas in both lungs.  Mosaic attenuation and bronchiectasis were not present. The patient had a smoking history of 30 packs/year. The findings favoured smoking-related lung disease. Thus, the presence of diffuse MIBI lung uptake in our case was considered to be associated with smoking-related lung disease and probably desquamative interstitial pneumonia (DIP). This type of diffuse uptakes has been reported in cases with COVID-19 infection, HIV-associated lymphocytic interstitial pneumonitis, chemical pneumonitis, miliary tuberculosis, pulmonary interstitial fibrosis and end-stage restrictive heart failure in the literature. Determination of the underlying cause of diffuse MIBI lung uptake in scintigraphic studies is a fairly atypical condition. To the best of our knowledge, it is the first case report on this subject. Incidental MIBI lung uptake merits further evaluation.