Answer:
Atoll / Reversed halo sign in Cryptogenic organising pneumonia.
Findings:
Images show peribronchovascular areas of consolidation, one of these lesions has focal round area of ground-glass attenuation and surrounding air-space consolidation of ring shape, giving positive.
Discussion:
Reversed halo sign is defined as a central ground glass opacity surrounded by denser consolidation shaped like a crescent (forming more than three quarters of a circle) or ring (forming a complete circle) that is at least 2 mm in thickness. The reversed halo sign seen on CT appears to be relatively specific to a diagnosis of cryptogenic organizing pneumonia . It is also reported in lymphomatoid granulomatosis, sarcoidosis, pulmonary paracoccidioidomycosis and other pulmonary fungal infections . Voloudaki et al. reported that the central ground glass opacity corresponds histopathologically to the area of alveolar septal inflammation (inflammatory infiltratesin the alveolar septum with macrophages, lymphocytes, plasmatic cells and some giant cells, with a relative preservation of alveolar spaces) and cellular debris and that the ring-shaped or crescentic peripheral air-space consolidation corresponds to the area of organizing pneumonia within the alveolar ducts.
Reference:
Signs in chest imaging; Diagn Interv Radiol 2011; 17:18–29 © Turkish Society ofRadiology 2011
Contributed By: Dr. Karunakaran M. Kalathi MD, Dr. Arun Chelladurai MD
Consultant Radiologists, Aarthi Scans, Thirunelveli, Tamilnadu, India
Atoll / Reversed halo sign in Cryptogenic organising pneumonia.
Findings:
Images show peribronchovascular areas of consolidation, one of these lesions has focal round area of ground-glass attenuation and surrounding air-space consolidation of ring shape, giving positive.
Discussion:
Reversed halo sign is defined as a central ground glass opacity surrounded by denser consolidation shaped like a crescent (forming more than three quarters of a circle) or ring (forming a complete circle) that is at least 2 mm in thickness. The reversed halo sign seen on CT appears to be relatively specific to a diagnosis of cryptogenic organizing pneumonia . It is also reported in lymphomatoid granulomatosis, sarcoidosis, pulmonary paracoccidioidomycosis and other pulmonary fungal infections . Voloudaki et al. reported that the central ground glass opacity corresponds histopathologically to the area of alveolar septal inflammation (inflammatory infiltratesin the alveolar septum with macrophages, lymphocytes, plasmatic cells and some giant cells, with a relative preservation of alveolar spaces) and cellular debris and that the ring-shaped or crescentic peripheral air-space consolidation corresponds to the area of organizing pneumonia within the alveolar ducts.
Reference:
Signs in chest imaging; Diagn Interv Radiol 2011; 17:18–29 © Turkish Society ofRadiology 2011
Contributed By: Dr. Karunakaran M. Kalathi MD, Dr. Arun Chelladurai MD
Consultant Radiologists, Aarthi Scans, Thirunelveli, Tamilnadu, India