AJR 2004; 182:92-94
© American Roentgen Ray Society
CT with Histopathologic Correlation of FDG Uptake in a Patient with Pulmonary Granuloma and Pleural Plaque Caused by Remote Talc Pleurodesis
Minh Nguyen1,
Vijay Varma2,
Rafael Perez3 and
David M. Schuster4
1 Department of Radiology, Division of Nuclear Medicine, Atlanta VAMC, 1670
Clairmont Rd., Decatur, GA 30033.
2 Department of Pathology, Atlanta VAMC, Decatur, GA 30033.
3 Department of Pulmonary, Allergy, and Critical Care Medicine, Atlanta VAMC,
Decatur, GA 30033.
4 Department of Radiology, Division of Nuclear Medicine, Emory University
Hospital, 1364 Clifton Rd., NE, Atlanta, GA 30322.
Received April 4, 2003;
accepted after revision June 10, 2003.
Address correspondence to D. M. Schuster
(david_schuster{at}emoryhealthcare.org).
Introduction
FDG scanning with coincidence and dedicated full-ring positron emission
tomography (PET) systems is valuable in the diagnosis and staging of lung
cancer. However, false-positive uptake in benign lung lesions has also been
documented [1]. Talc
pleurodesis (3 MgO x 4 SiO2 x H2O) is an
increasingly common procedure used in the treatment of persistent pneumothorax
and pleural effusions from malignant and nonmalignant causes
[2]. Murray et al.
[3] described a case of
presumed benign FDG uptake within high-attenuation pleural plaques from talc
pleurodesis performed 10 months before imaging. It was not known how long this
pleural inflammation would be seen on PET. We describe a case of FDG uptake
within both high-attenuation pulmonary nodules and pleural plaque from talc
pleurodesis completed 3 years earlier. Biopsy of the lung nodules confirmed
the benign nature of the findings.
Case Report
A 53-year-old man presented to the pulmonary service from an outside
facility with a right lower lobe lung nodule that was discovered on chest
radiography and confirmed with subsequent chest CT and with positive findings
on a FDG PET scan. Bronchoscopy performed at the outside facility was
nondiagnostic. The patient complained of occasional right-sided pleuritic
chest wall pain and cough, but denied hemoptysis or weight loss. Medical
history was remarkable for 90-pack-year tobacco abuse and chronic obstructive
pulmonary disease. Three years earlier, the patient had been treated for a
spontaneous right-sided pneumothorax with a chest tube and talc pleurodesis.
There was no history of tuberculosis exposure, and purified protein derivative
test result was negative. There was no known history of asbestos exposure. The
patient's physical examination was unremarkable.
Because 6 months had passed since his initial evaluation, a repeated
focused chest CT scan was obtained and FDG coincidence imaging was performed
to follow up and further characterize the nodule. CT revealed a
well-circumscribed, lobulated, partially calcified 11 x 9 mm nodule in
the posterior segment of the right upper lobe adjacent to the fissure
(Fig. 1A) that showed FDG
uptake (Fig. 1B). A curvilinear
high-attenuation plaque within the right posterior costophrenic sulcus
(Fig. 1C) with intense FDG
uptake (Fig. 1D) was also
present. No hilar or mediastinal lymphadenopathy was seen. In addition, a
second 5-mm noncalcified nodule with FDG uptake was present in the superior
segment of the right lower lobe near the pleural surface (not shown). No other
areas of abnormal FDG uptake were noted.
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Fig. 1A. —53-year-old man with history of talc pleurodesis and right
pulmonary nodules. CT scan shows partially calcified pulmonary nodule
(arrow) in posterior segment of right upper lobe adjacent to
fissure.
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Fig. 1B. —53-year-old man with history of talc pleurodesis and right
pulmonary nodules. FDG positron emission tomography (PET) image shows
increased metabolic activity (arrow) at location of pulmonary nodule
seen in A.
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The patient was highly anxious because of the possibility of cancer within
the lung nodules, and he requested surgical removal. The patient then
underwent a right lateral exploratory thoracotomy. Microscopic examination of
the two excised nodules showed foreign-body reactions with birefringence,
which is characteristic of talc granulomas (Figs.
1E and
1F). The presence of
multinucleated giant cells admixed with lymphocytes is indicative of ongoing
inflammation. Although the high-attenuation pleural plaque was not biopsied,
it was presumed to represent the same benign process.
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Fig. 1E. —53-year-old man with history of talc pleurodesis and right
pulmonary nodules. Photomicrograph of histopathologic specimen shows granuloma
composed of numerous multinucleated giant cells (arrow) admixed with
lymphocytes. Note intracellular material. (H and E, x400)
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Fig. 1F. —53-year-old man with history of talc pleurodesis and right
pulmonary nodules. Photomicrograph of histopathologic specimen from E
under polarized light shows intracellular birefringent crystals
(arrow), characteristic of talc granuloma. (H and E, x100)
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Discussion
Talc pleurodesis is an inexpensive and effective treatment for pneumothorax
[2]. Pleural talc deposits are
most often described as areas of increased attenuation in the posterior caudal
regions of the pleural space that are best imaged on CT
[4,
5]. Murray et al.
[3] hypothesized that these
areas can also have increased FDG uptake on PET because of granulomatous
inflammation. FDG uptake was noted in their patient 10 months after the
initial pleurodesis.
Talc pleurodesis may produce high-attenuation pulmonary parenchymal
nodules, probably because of talc-particle absorption through the pleura.
Werebe et al. [6] described the
rapid absorption of talc in a rat model through the pleura into the systemic
circulation that was deposited in the coronary arteries, meninges, and
pulmonary arteries within 24 hr. Another possibility, as shown by Kennedy et
al. [7] in their rabbit model,
is that talc particles are transported into the parietal pleural lymphatics
and then to the mediastinal lymph nodes and thoracic duct, where they enter
the systemic venous circulation and are deposited into the lung periphery.
Although there has not been, to our knowledge, a human study of this nature,
several cases of acute respiratory distress syndrome after talc pleurodesis
have been reported [8]. These
patients had talc crystals in their bronchoalveolar lavage performed
10–12 hr after thoracoscopy.
False-positive FDG uptake can be seen in various granulomatous,
inflammatory, and infectious diseases such as Wegener's granulomatosis,
sarcoidosis, histiocytosis, rheumatoid arthritis, fungal or mycobacterial
infections, bacterial pneumonia, and postradiation pneumonitis or fibrosis
[1].
In this case, another cause of false-positive uptake simulating malignant
lung nodules and pleural deposits is reported: remote talc pleurodesis.
Intense FDG uptake was seen in the high-attenuation nodules and plaque, even
though the pleurodesis had been performed 3 years previously. We hypothesize
that granulomatous inflammation from talc pleurodesis is intense and chronic.
Therefore, FDG uptake would persist as long as the talc crystals are present.
Long-term follow-up PET scanning could confirm this persistent uptake. Careful
correlation with the patient's clinical history and correlative imaging
techniques such as CT are required to avoid misdiagnosing malignancy in
patients with a history of talc pleurodesis.
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Introduction
Case Report
