132 AJTCCM VOL. 30 NO. 3 2024
PICK OF THE PICS
A 37-year-old immunocompetent man
presented to a local clinic with a 6-month
history of pleuritic chest pain and dry
cough. He had no background medical
history and reported no other respiratory
or constitutional symptoms. Clinical
examination was unremarkable. A chest
computed tomography scan revealed the
reversed halo sign (RHS) in both upper
lobes (Fig.1), and serological investigations
revealed strongly positive anti-proteinase
3 antibody, which is suggestive of
granulomatosis with polyangiitis (GPA).
GPA is a small-vessel antineutrophil
cytoplasmic antibody-associated vasculitis
with multisystem involvement including
the musculoskeletal system, skin, kidney
and heart, but typically aecting the upper
airway with nasal and ear symptoms.[1] e
radiological pulmonary manifestations of
GPA include nodules, ground-glass opacities
and consolidation.[2]
The reversed halo comprises two parts:
an inner area of ground-glass opacication
and a complete or near-complete outer
ring of surrounding consolidation, initially
thought to be a specic feature of cryptogenic
organising pneumonia.[3] e central area of
ground-glass opacification represents an
area of alveolar septal inflammation with
non-disrupted alveolar air spaces, while the
surrounding denser ring is consistent with
debris in the alveolar space.[4]
In the past, the RHS was considered almost
pathognomonic for cryptogenic organising
pneumonia, but the differential diagnosis
is vast and includes many non-infectious
and infectious pathologies (Table 1). In
immunocompromised patients, fungal
pneumonias are a major concern.[4]
The differential diagnosis of the RHS is
vast and requires an in-depth clinical and
radiological assessment in order to make a
diagnosis. Although GPA may be uncommon,
it remains an important consideration in the
correct clinical context.
1. Frankel SK, Schwarz MI. e pulmonary vasculitides.
Am J Respir Crit Care Med 2012;186(3):216-224.
https://doi.org/10.1164/rccm.201203-0539ci
2. Gómez-Gómez A, Martínez-Martínez MU,
Cuevas-Orta E, et al. Pulmonary manifestations
of granulomatosis with polyangiitis. Reumatol
Clín 2014;10(5):288-293. https://doi.org/10.1016/j.
reumae.2014.03.007
3. Godoy MCB, Viswanathan C, Marchiori E, et al. e
reversed halo sign: Update and dierential diagnosis.
Br J Radiol 2012;85(1017):1226-1235. https://doi.
org/10.1259/bjr/54532316
4. Maturu VN, Agarwal R. Reversed halo sign: A
systematic review. Respir Care 2014;59(9):1440-1449.
https://doi.org/10.4187/respcare.03020
What is the cause of the reversed halo sign in this patient?
W du Plessis, MB ChB
Division of Pulmonology, Department of Medicine, Faculty of Medicine and Health Sciences, Stellenbosch University and Tygerberg Hospital, Cape Town, South Africa
duplessiswesley5@gmail.com
Fig. 1. Computed tomography scan image depicting the reversed halo sign, with outer ring of
consolidation (rightward arrow) and inner ring of ground-glass opacication (upward arrow).
Table 1. Causes of the reversed halo sign[3]
Infectious Non-infectious, benign Malignant and related
Invasive or endemic fungal
infection
Pneumocystis jirovecii
Tuberculosis
Bacterial
Organising pneumonia
Nonspecic interstitial
pneumonia
Sarcoidosis
Lipoid pneumonia
Granulomatosis with
polyangiitis
Lymphomatoid
granulomatosis
Lung adenocarcinoma
Pulmonary metastases
Post radiofrequency
ablation or radiation
