By Alex Hsu, MD, PhD, Paul Stark, MD, and Paul J. Friedman, MD
Focal organizing pneumonia with reversed halo sign
A chest radiograph (Figure 1) showed pleural thickening in the
region of the costophrenic sulcus, enlargement of the hilar and
paratracheal lymph nodes, and a mass in the right upper lobe. A CT
rmed the mass and
its solid peripheral margin and heterogeneous center (Figure 2).
Bronchoscopy and ﬁ
aspiration of the right-upper-lobe opacity revealed lymphoid cells.
</<span class="end-tag" />P
>Over the next 3 years, the patient underwent
chemotherapy for CLL. A follow-up CT scan of the chest 3 years
later showed the same right-upper-lobe lesion, which was unchanged
in size and texture. </<span class="end-tag" />P
Organizing pneumonia occurs over a wide age range—
most commonly in the ﬁ
fth and sixth decades of
without a gender
preference. Patients have vague symptoms, usually a subacute
presentation of fever, nonproductive cough, malaise, weight loss,
and mild dyspnea over a time course of weeks to months.<Sup
>1 </<span class="end-tag"
/>Sup>The physical examination often yields lung crackles in
the affected areas, but the examination may be normal. On pulmonary
function tests, a mild-to-moderate restrictive pattern, reduced
carbon monoxide diffusion capacity, and mild hypoxemia are
exhibited. Laboratory ﬁ
ndings are consistent with an
including mild leukocytosis and elevations in C-reactive protein
and erythrocyte sedimentation rate. </<span class="end-tag"
>The histopathologic features of organizing pneumonia
reveal intra-alveolar and intrabronchiolar polypoid granulation
tissue, so-called Masson bodies, with ﬁ
broblasts, and loose connective
tissue. Sometimes the granulation tissue contains inﬂ
ammatory cells, eg, macrophages,
plasma cells, and neutrophils with eosinophilia.<Sup
>1,2 </<span class="end-tag"
/>Sup></<span class="end-tag" />P
>Chest radiography commonly shows patchy, bilateral lower
lobe areas of parenchymal opacity with a bias for the periphery of
the lung. Air bronchograms can be present. On CT, several different
manifestations of organizing pneumonia have been described. The
most common appearance consists of bilateral, patchy, consolidative
and ground-glass opacities, which are seen more often in the
peripheral and lower lung regions. The dimensions range from a few
centimeters to an entire lobe of the lung. Other presentations of
organizing pneumonia include focal lesions, ringlike shadows, and
nodular, bronchocentric, perilobular, and bandlike opacities.
</<span class="end-tag" />P
>Focal organizing pneumonia may be difﬁ
cult to distinguish from malignancy.
Diagnosis often requires biopsy or resection, which may yield a
solitary mass with an irregular margin and spiculation. The mass
tends to be ﬂ
at or ovoid
(rather than rounded) and may contain air bronchograms or may
cavitate. It tends to be peripheral in location and may be in
contact with the pleura. </<span class="end-tag" />P
>A linear pattern of organizing pneumonia occurs in
isolation or along with other patterns. It is seen as 2-cm or
longer bands or arcs of opacity that measure at least 8 mm in
width. Its margins may be smooth or irregular. Air bronchograms may
be present. These bands may either extend toward the lung periphery
in a radial fashion associated with bronchi or may appear
peripheral without association with bronchi. </<span
>A recently described unusual appearance of organizing
pneumonia consists of rings and crescents; initially 2 cases were
described by Voloudaki et al.<Sup
>3 </<span class="end-tag"
/>Sup>This appearance has also been dubbed the “
reversed halo sign”
(Figures 1 through 4). It consists of
a central area of ground-glass opacity that is surrounded
completely or partially by a ring or crescent of consolidation.
Histologically, the central ground-glass area corresponds to
alveolar septal inﬂ
and cellular debris, while the outside ring or crescent represents
granulation tissue within alveoli and bronchioles (Figures 5 and
6). </<span class="end-tag" />P
>Historical review of CT scans from patients with
biopsy-proven organizing pneumonia by Kim et al<Sup
>4 </<span class="end-tag"
/>Sup>revealed a ring or crescent pattern in 6 of 31
class="end-tag" />Sup>A small comparison group of patients
with biopsy-proven Wegener’
granulomatosis, bronchioloalveolar carcinoma, eosinophilic
pneumonia, or Churg-Strauss syndrome failed to show any similar CT
ndings of a ring or
crescent pattern. This suggests that the reversed halo, ring, or
crescent patterns are more speciﬁ
c for organizing pneumonia than are
the most commonly seen patchy ground-glass and consolidative
patterns. </<span class="end-tag" />P
class="end-tag" />B></<span class="end-tag"
>The reverse halo sign is an uncommon but relatively
c radiologic sign of
cryptogenic organizing pneumonia. Radiologists should become
familiar with this relatively new addition to the spectrum of
organizing pneumonia. </<span class="end-tag" />P
>Cordier JF. Organising pneumonia. Thorax.
2000;55:318-328. </<span class="end-tag" />LI
>Oikonomou A, Hansell DM. Organizing pneumonia: The many
morphological faces. Eur Radiol. 2002;12:1486-1496. </<span
>Voloudaki AE, Bouros DE, Froudarakis ME, et al.
Crescentic and ring-shaped opacities. CT features in two cases of
bronchiolitis obliterans organizing pneumonia (BOOP). Acta Radiol.
1996;37:889-892. </<span class="end-tag" />LI
>Kim SJ, Lee KS, Ryu YH, et al. Reversed halo sign on
high-resolution CT of cryptogenic organizing pneumonia: Diagnostic
implications. AJR Am J Roentgenol. 2003;180:1251-1254
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