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Adenocarcinoma of the Lung Presenting as a Mycetoma With an Air Crescent Sign* FREE TO VIEW

Lan-Fu Wang, MD; Hsi Chu, MD; Yuh-Min Chen, MD, PhD, FCCP; Reury-Perng Perng, MD, PhD, FCCP
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*From the Chest Department, Taipei Veterans General Hospital, Taipei, Taiwan, Republic of China.

Correspondence to: Yuh-Min Chen, MD, PhD, FCCP, Chest Department, Taipei Veterans General Hospital, 201 Section 2, Shih-Pai Rd, Taipei 112, Taiwan, Republic of China; e-mail: ymchen@vghtpe.gov.tw



Chest. 2007;131(4):1239-1242. doi:10.1378/chest.06-1551
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An 89-year-old man was admitted to the hospital due to intermittent anterior chest wall pain for > 1 month. A chest radiograph obtained on November 9, 2004, demonstrated a mass with an irregular border, inside a thin-walled cavity, located in the superior segment of the left lower lobe. A chest CT scan revealed an irregular thin-walled cavity, 5.9 × 5.4 × 4 cm in size, with an air-crescent sign in the superior segment of the left lower lobe, and an intracavitary fungus ball-like mass. A bronchoscopic examination was performed, revealing only external compression of the left lower lobe bronchial lumen. Cultures from both the brushing cytology and brushing fungus specimens were negative. Since the patient was a heavy smoker and the chest radiograph obtained 23 months before had revealed no active pulmonary lesion, neoplastic growth was still highly suspected. Thus, an 18F-fluoro-2-deoxyglucose positron emission tomography study was performed on November 25, and a mass with a slightly increased standard uptake value (3.17; cutoff value, 2.5) was found. He received a left lower lobe lobectomy on December 23, and a tumor with many septum-like structures connecting the surrounding pulmonary parenchymal tissue was found in the superior segment of the left lower lobe. The final pathologic diagnosis was adenocarcinoma of the lung (pT2N0M0). Thus, even though the chest radiograph and chest CT scan showed a typical air-crescent sign (ie, mass inside a cavity) favoring a mycetoma, the physician should still keep in mind that lung cancer may also unusually present in this way.

Figures in this Article

An 89-year-old man was admitted to the hospital on November 9, 2004, due to intermittent anterior chest wall pain for > 1 month. No fever, cough, or body weight loss was noted. His medical history included ischemic heart disease, which was under regular medical control. He had smoked 10 cigarettes daily for > 40 years. A physical examination revealed no remarkable findings. The chest radiograph obtained on hospital admission revealed a thin-walled cavity and a mass with an irregular border inside the cavity, which was located in the superior segment of the left lower lobe. A chest CT scan revealed a thin-walled cavity with irregular outer border, 5.9 × 5.4 × 4 cm in size, with an air-crescent sign, in the superior segment of the left lower lobe, and an intracavitary fungus ball-like mass (Fig 1 ). The thickness of this thin, wall-like structure was approximately 2 to 5 mm, with a less clear outside border infiltrating into the pulmonary parenchyma. Bronchoscopic examination disclosed a narrowing of the left lower lobe bronchial lumen, caused by external compression. Brushing cytology, acid-fast bacilli smear and culture, and fungus culture showed negative results. Since the patient was a smoker and the chest radiograph obtained in December 2003 had shown no active pulmonary lesion, pulmonary neoplastic growth was still highly suspected. Thus, an 18F-fluoro-2-deoxyglucose (FDG) positron emission tomography (PET) scan was arranged, and the resulting images showed a homogenous mass 6.1 × 6 × 6.1 cm in the left lower lobe (Fig 2 ). The standard uptake value (SUV) of the FDG uptake was 3.17 for this mass. Since a mycetoma would not be expected to have any uptake on PET scanning, because it does not have a blood supply, any uptake at all within the central solid lesion would rule out the presence of a mycetoma. Thus, the PET scan results excluded the possibility of mycetoma in our patient. He then underwent a left lower lobe lobectomy. The operative findings were a mass with many septum-like structures connecting the surrounding pulmonary parenchymal tissue in the superior segment of the left lower lobe (Fig 3 ), and the final pathologic diagnosis was adenocarcinoma of the lung (pT2N0M0) [Fig 4 ].

Lung cancer is the leading cause of cancer death in the world. The common radiologic presentations of lung cancer patients include a solitary pulmonary nodule, lung consolidation, collapse, pleural effusion, and/or mediastinal widening. Lung cancer presenting with an air-crescent sign or as a mycetoma-like lesion is very rare. This air-crescent sign seen (ball-in-hole) in the chest radiograph or chest CT scan is most often associated with an inflammatory process such as mycetoma, a hydatid cyst, lung abscess, or pulmonary tuberculosis (TB).1Mycetoma frequently occurs in preexisting cavitary lesions of the lung formed by a previous pulmonary tuberculous infection. In addition to combining with mycetoma, pulmonary TB can also be found together with lung cancer, simultaneously or sequentially.2 However, in our previous large-scale retrospective analysis2of 31 patients with pulmonary TB and lung cancer from 1988 to 1994, including 3,928 lung cancer patient profiles, we never found a cavitary TB lesion with mycetoma inside the cavity, combined with another lung cancer lesion, in the same patient. Mycetoma was more frequently suspected or misdiagnosed as lung cancer,3and only rarely did mycetoma arise from a cavitary lesion within lung cancer.4

Although lung cancer can occur after previous pulmonary injury, such as a scar cancer growing from a fibrotic or granuloma lesion due to previous pulmonary TB infection, the majority of lung cancers are due to smoking. Even in those lung cancers that derive from previous pulmonary injury, the majority of lesions are located at or derived from a fibrotic or granuloma lesion, instead of a TB cavity. When lung cancer does occur in a previously existing cavity, one will find, in addition to typical fibronodular lesions distributed in the lung, an irregular nodular lesion, which progressively enlarges, inside a chronic preexisting TB cavity. In contrast, no evidence of any pulmonary TB lesions was found in the image study of our case; thus, pulmonary TB with a TB cavity and tumor growth inside the cavity was much less likely to have been our clinical impression before the patient received surgical intervention. The reason why our patient had a ball-in-hole or an air-crescent sign appearance in the chest image was that the tumor infiltrated with a paracicatrical effect around the peripheral pulmonary parenchyma, thus inducing compensatory emphysematous or cystic change between the tumor-infiltrating bands. This was documented by both the surgical gross specimens and pathologic findings.

In addition, in patients with a pulmonary mycetoma (fungal ball), the radiographic feature is usually evident as an upper lobe cavitary lesion with an intracavitary mobile mass and an air-crescent sign on the periphery.56 A change in the position of the mycetoma occurring when the patient changes his position is a valuable radiologic sign for the diagnosis of mycetoma.5,7 Thus, the classic CT scan workup of a mycetoma would include both supine and prone scanning studies to demonstrate whether the central mass is free or attached to the cystic wall.

The reason we performed a PET scan to rule out a malignancy is that the patient was a heavy smoker and his chest radiograph examination from 23 months before had negative findings, implying a greater possibility of cancer formation. PET scanning is a sensitive imaging method for both inflammatory processes and malignancies.8Many inflammatory lesions have a maximal SUV of < 2.5, and the specificity of this cutoff SUV was approximately 70 to 90% in one study.9In addition to the SUV data, PET imaging itself is another important differentiating clue, as a fungus ball will show a cavitary lesion with an increased SUV at the wall of the cavity, with no radioactivity inside the cavity, since mycetoma does not have a blood supply. Thus, any uptake at all within the central solid lesion would rule out the presence of a mycetoma (Fig 5 ). Topologically, the hyphae are still outside the patient’s body, so the mycetoma is more of a colonization than an infection, similar to the microbes found on the skin surface; this also explains why there would be no uptake at all within the solid portion of a mycetoma, but only around the edges of the host cavity, as shown in Figure 5. Thus, a mycetoma will have increased uptake in the wall of the cavity on PET scans, but not in the fungal ball. In contrast, in patients with lung cancer a mass with increased SUV (Fig 2) is revealed. In patients with lung cancer, PET scanning is usually incorporated into the conventional staging algorithms for a patient with non-small cell lung cancer10 and is also able to evaluate the primary lesion.9

In conclusion, the physician should keep in mind that lung cancer may have an air-crescent sign or mycetoma-like appearance in the roentgenographic images. In addition to clinical history and chest imaging studies obtained with the patient in both the supine and prone positions, PET scan images can help in the differential diagnosis.

Abbreviations: FDG = 18F-fluoro-2-deoxyglucose; PET = positron emission tomography; SUV = standard uptake value; TB = tuberculosis

The authors have reported to the ACCP that no significant conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Figure Jump LinkFigure 1. Chest CT scan shows one 5.9 × 5.4 × 4 cm cavitary lesion with an irregular thin wall, and one 4.6 × 3.1 × 3 cm lobulated mass in the center (with an air-crescent sign), in the superior segment of the left lower lobe. Top, A: coronal section of the three-dimensional reconstruction. Bottom, B: cross section of the lung window view. The thickness of this irregular wall was about 2 to 5 mm, with a less clear outside border infiltrating into the pulmonary parenchyma.Grahic Jump Location
Figure Jump LinkFigure 2. FDG-PET scan shows an obvious and homogeneous mass with an SUV of 3.17, located over the left lower lobe (arrow).Grahic Jump Location
Figure Jump LinkFigure 3. A gray-white firm tumor, 4.2 × 3.5 × 2.2 cm in size, with some septum-like structures in the peripheral region, was noted inside the left lower lobe (17 × 7.2 × 4.8 cm).Grahic Jump Location
Figure Jump LinkFigure 4. Microscopic finding of sections of the left lower lobe tumor shows well-differentiated adenocarcinoma with a papillary growth pattern (hematoxylin-eosin, original ×100).Grahic Jump Location
Figure Jump LinkFigure 5. Chest CT scan (top, A) and PET scan image (bottom, B) of a 74-year-old man with a pulmonary mycetoma of the right upper lobe. The CT scan (top, A) shows a mass inside a thin-walled cavity located in the right upper lobe (arrow). A PET scan (bottom, B) from November 16, 2000, shows a mass in the lung with an absence of radioactivity in the central portion and a slightly increased FDG uptake (SUV, 1.63 vs 0.45 in a contralateral normal lung) at the periphery of the lesion, which is compatible with mycetoma of the lung rather than a malignancy (arrow).Grahic Jump Location
Abramson, S (2001) The air crescent sign.Radiology218,230-232. [PubMed]
 
Chen, YM, Lee, PY, Chao, JY, et al Shortened survival of lung cancer patients with active pulmonary tuberculous infection.Jpn J Clin Oncol1996;26,322-327. [PubMed] [CrossRef]
 
Torpoco, JO, Yousuffuddin, M, Pate, JW Aspergilloma within a malignant pulmonary cavity.Chest1976;69,561-563. [PubMed]
 
Osinowo, O, Softah, AL, Zahrani, K, et al Pulmonary aspergilloma simulating bronchogenic carcinoma.Indian J Chest Dis Allied Sci2003;45,59-62. [PubMed]
 
Shuji, B, Jiro, F, Yoko, F, et al Cavitary lung cancer with an aspergilloma-like shadow.Lung Cancer1999;26,195-198. [PubMed]
 
Ayman, OS, Pranatharthi, HC The clinical spectrum of pulmonary aspergillosis.Chest2002;121,1988-1999. [PubMed]
 
Roberts, CM, Citron, KM, Strickland, B Intrathoracic aspergilloma: role of CT in diagnosis and treatment.Radiology1987;165,123-128. [PubMed]
 
Reichenberger, F, Habicht, JM, Gratwohl, A, et al Diagnosis and treatment of invasive pulmonary aspergillosis in neutropenic patients.Eur Respir J2002;19,743-755. [PubMed]
 
Ho, CL Clinical PET imaging: an Asian perspective.Ann Acad Med Singapore2004;33,155-165. [PubMed]
 
Victor, K, Rodney, JH, Michael, PM, et al Clinical impact of F-fluorodeoxyglucose positron emission tomography in patients with non-small cell lung cancer: a prospective study.J Clin Oncol2001;19,111-118. [PubMed]
 

Figures

Figure Jump LinkFigure 1. Chest CT scan shows one 5.9 × 5.4 × 4 cm cavitary lesion with an irregular thin wall, and one 4.6 × 3.1 × 3 cm lobulated mass in the center (with an air-crescent sign), in the superior segment of the left lower lobe. Top, A: coronal section of the three-dimensional reconstruction. Bottom, B: cross section of the lung window view. The thickness of this irregular wall was about 2 to 5 mm, with a less clear outside border infiltrating into the pulmonary parenchyma.Grahic Jump Location
Figure Jump LinkFigure 2. FDG-PET scan shows an obvious and homogeneous mass with an SUV of 3.17, located over the left lower lobe (arrow).Grahic Jump Location
Figure Jump LinkFigure 3. A gray-white firm tumor, 4.2 × 3.5 × 2.2 cm in size, with some septum-like structures in the peripheral region, was noted inside the left lower lobe (17 × 7.2 × 4.8 cm).Grahic Jump Location
Figure Jump LinkFigure 4. Microscopic finding of sections of the left lower lobe tumor shows well-differentiated adenocarcinoma with a papillary growth pattern (hematoxylin-eosin, original ×100).Grahic Jump Location
Figure Jump LinkFigure 5. Chest CT scan (top, A) and PET scan image (bottom, B) of a 74-year-old man with a pulmonary mycetoma of the right upper lobe. The CT scan (top, A) shows a mass inside a thin-walled cavity located in the right upper lobe (arrow). A PET scan (bottom, B) from November 16, 2000, shows a mass in the lung with an absence of radioactivity in the central portion and a slightly increased FDG uptake (SUV, 1.63 vs 0.45 in a contralateral normal lung) at the periphery of the lesion, which is compatible with mycetoma of the lung rather than a malignancy (arrow).Grahic Jump Location

Tables

References

Abramson, S (2001) The air crescent sign.Radiology218,230-232. [PubMed]
 
Chen, YM, Lee, PY, Chao, JY, et al Shortened survival of lung cancer patients with active pulmonary tuberculous infection.Jpn J Clin Oncol1996;26,322-327. [PubMed] [CrossRef]
 
Torpoco, JO, Yousuffuddin, M, Pate, JW Aspergilloma within a malignant pulmonary cavity.Chest1976;69,561-563. [PubMed]
 
Osinowo, O, Softah, AL, Zahrani, K, et al Pulmonary aspergilloma simulating bronchogenic carcinoma.Indian J Chest Dis Allied Sci2003;45,59-62. [PubMed]
 
Shuji, B, Jiro, F, Yoko, F, et al Cavitary lung cancer with an aspergilloma-like shadow.Lung Cancer1999;26,195-198. [PubMed]
 
Ayman, OS, Pranatharthi, HC The clinical spectrum of pulmonary aspergillosis.Chest2002;121,1988-1999. [PubMed]
 
Roberts, CM, Citron, KM, Strickland, B Intrathoracic aspergilloma: role of CT in diagnosis and treatment.Radiology1987;165,123-128. [PubMed]
 
Reichenberger, F, Habicht, JM, Gratwohl, A, et al Diagnosis and treatment of invasive pulmonary aspergillosis in neutropenic patients.Eur Respir J2002;19,743-755. [PubMed]
 
Ho, CL Clinical PET imaging: an Asian perspective.Ann Acad Med Singapore2004;33,155-165. [PubMed]
 
Victor, K, Rodney, JH, Michael, PM, et al Clinical impact of F-fluorodeoxyglucose positron emission tomography in patients with non-small cell lung cancer: a prospective study.J Clin Oncol2001;19,111-118. [PubMed]
 
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