Yonago Acta medica 2008;51:69–72

Inflammatory Pseudotumor of the Lung Identified by18F-Fluorodeoxyglucose Positron Emission Tomography:
A Patient Report
Yuzo Takagi, Hiroshige Nakamura*, Ken Miwa*, Yoshin Adachi*, Shinji Fujioka*,
Tomohiro Haruki*, Yuji Taniguchi* and Yasushi Horie†
Center for Clinical Residency Program, *Division of General Thoracic Surgery and †Pathology
Division, Tottori University Hospital, Yonago 683-8504 Japan

The patient was a 71-year-old man with an abnormal shadow on chest X-ray. Computed
tomography (CT) of the chest showed a tumor of 38 mm in size in the upper lobe of theleft lung S3. A CT-guided lung biopsy was performed, but no malignancy was observed.
18 F-fluorodeoxyglucose (FDG) positron emission tomography (PET) revealed a high
FDG uptake in the tumor: the maximum and mean values of the standard FDG uptake
in the early phase were 7.3 and 5.3, respectively, and those in the latter phase, 8.3 and5.9, respectively. The hilar and mediastinal lymph nodes also showed positive for high
FDG uptakes. We strongly suspected lung cancer, and performed a left upper lobectomy by video-assisted thoracic surgery. The pathological diagnosis was an inflammatory
pseudotumor of the lung: it is a rare disease but often requires differentiation from lungcancer. Literature has been few on FDG-PET about inflammatory pseudotumor of thelung. Differentiation of the disease from lung cancer was especially difficult in the present patient, because both lymph nodes and the tumor showed high FDG uptakes.
Key words: 18F-fluorodeoxyglucose positron emission tomography; lung inflammatory pseudotumor; video-assisted thoracic surgeryof our patient, with bibliographical considerations
as well.

Inflammatory pseudotumor of the lung has been
more frequently detected due to the recent progressin diagnostic imaging, but it is difficult to differentiate from lung cancer. In many patients, the diagnosis is confirmed with surgery. We have encountered a male patient highly suspected of lung cancer due to his high uptake of 18F-fluorodeoxyglucose (FDG) in FDG-positron emission tomography(PET). We diagnosed his disease as inflammatory
pseudotumor of the lung via video-assisted thoracicsurgery. Few literature focuses on FDG-PET andinflammatory pseudotumor of the lung. The present patient showed a high FDG uptake also in thelymph node, which made us confused in differentiating from lung cancer. We herein present the case

Patient Report
This 71-year-old man had undergone medical examinations every year, but no abnormalities weredetected. In July 2007, he had general fatigue andhemosputum, and visited nearby hospital where anabnormal shadow in the left upper lung was foundon examination. He was referred to our University Hospital. Laboratory findings at the time ofadmission were a white blood cell count of 6,100/
μL without any left shift of the nucleus, and theAbbreviations: CT, computed tomography; FDG, 18F-fluorodeoxyglucose; PET, positron emission tomography

69

Y. Takagi et al.

C-reactive protein level of 0.52 mg/dL. General orbiochemical examinations of the blood showed noother abnormalities, and all of the tumor markers
were negative. Chest X-ray showed a nodular density with approximately 40 mm in size in the left
upper lung (Fig. 1). Chest computed tomography(CT) visualized a 38 × 32 mm tumor in size having broad contact with the parietal pleura in the left
upper lobe S3 (Fig. 2). The periphery of the tumor
was irregular, and the boundary was relatively
well defined. Lymph nodes were enlarged at boththe hilar and the mediastinal regions. In FDGPET (Fig. 3), we observed a high FDG uptake justmatching the tumor. The maximum and meanvalues of the standard FDG uptake in the earlyphase were 7.3 and 5.3, respectively, and those in
the latter phase, 8.3 and 5.9, respectively. In addition, high FDG uptake was also observed inboth the hilar and the mediastinal regions, so lungFig. 1. Chest X-ray showed an irregular-circumscribed
abnormal shadow in the left middle field of the lung.

cancer and metastases to the lymph nodes werestrongly suspected. The CT-guided lung biopsy
resulted in nonspecific inflammatory findings, andno malignant cells were observed. However, on
considering FDG-PET findings, lung cancer could
not be ruled out. Therefore, thoracoscopic surgery
was performed after obtaining informed consent
from the patient. The tumor had firmly adhered tothe parietal pleura, and a needle biopsy exhibitedno malignant cells on pathological tissues frozen
intraoperatively. We suspected an inflammatory
pseudotumor, and performed a simple left upper
lobectomy by video-assisted thoracic surgery. The
resected tumor (Fig. 4) was 38 × 32 mm in size,
sectionally xanthochromatic with mild anthracosis. Its shape was relatively regular in the periphery, well defined, solid and elastically soft. In thepathological tissue (Fig. 5), we found a lesion thatwas mainly comprised of organized pneumonic fibrosis, with inflammatory cell infiltration involving
lymphocytes and plasma cells. When the image ofthe area was enlarged on the monitor, we observed
inflammatory cells, fibrosis and spindle-shaped
mesenchymal cells, which led us to the diagnosis
of inflammatory pseudotumor, fibrous histiocytic
type of the lung. The patient’s postoperative course
was good, and no recurrence has been observed.

Fig. 2. Chest CT revealed an irregular tumor, 38 32
mm in size, having broad contact with the parietal pleurain the left upper lobe S3. CT, computed tomography.

Fig. 3. FDG-PET revealed a high FDG uptake justmatching the tumor, the hilar and mediastinal lymph
nodes (arrows). FDG, 18F-fluorodeoxyglucose; PET, positron emission tomography.

70