The galaxy sign represents coalescing granulomatous inflammation in sarcoidosis. Large nodules with surrounding micronodules are characteristic – even pathognomonic – of sarcoidosis.
Two patients with sarcoidosis demonstrating the galaxy sign:
“Large Coalescent Parenchymal Nodules in Pulmonary Sarcoidosis: “Sarcoid Galaxy” Sign.” Am J Roentgenol 2002.
Black Hole Sign
Patients with angioinvasive fungal pneumonia caused by Mucormycosis develop necrotizing infarction of the lung parenchyma. This portion of the parenchyma will be completely non-enhancing at MRI and appear as a ‘black hole.’
Black hole sign in the right upper lobe
“Pulmonary Mucormycosis: Radiologic Features at Presentation and Over Time” Am J Roentgenol 2018.
We have collected several cases from our institution of proven CoVID-19 disease. The majority of these display typical imaging manifestations: on chest radiograph, either diffuse interstitial opacities or peripheral airspace opacities; on CT, peripheral predominant ground glass or consolidative opacities.
Chest Radiograph
40-year-old man with peripheral-predominant airspace disease84-year-old woman. Note peripheral predominance in the right lung.60-year-old woman with diffuse interstitial opacities60-year-old man with diffuse interstitial opacities59-year-old man
Chest CT – Typical
78-year-old woman
Note peripheral opacity with reverse halo signAnd other more nodular opacity
31-year-old man
Peripheral patchy ground glass opacities
Chest CT – Atypical
83-year-old woman
Note diffuse ground glass with some septal thickening
80-year-old female
Small subpleural nodular opacity, unclear if related to CoVID-19Minimal septal thickening and pleural effusions, likely related to edema.
