Ann Thorac Surg 2008;86:1698. doi:10.1016/j.athoracsur.2007.12.078
© 2008 The Society of Thoracic Surgeons
Images in Cardiothoracic Surgery
Imaging Characteristics of a Mucinous Colorectal Pulmonary Metastasis
Elizabeth Belcher, MDa,b,c,
Andrew G. Nicholson, MDa,b,c,
David M. Hansell, MDa,b,c,
Peter Goldstraw, MDa,b,c,*
a Department of Thoracic Surgery, The Royal Brompton Hospital, London, United Kingdom
b Department of Histopathology, The Royal Brompton Hospital, London, United Kingdom
c Department of Radiology, The Royal Brompton Hospital, London, United Kingdom
* Address correspondence to Dr Goldstraw, Department of Thoracic Surgery, Royal Brompton Hospital, Sydney St, London, SW3 6NP, United Kingdom (Email: p.goldstraw{at}rbht.nhs.uk).
A 59-year-old farmer presented with a 6-month history of dry cough. A lifelong nonsmoker, he had undergone anterior resection 6 years previously for an adenocarcinoma of the rectum. A chest roentgenogram showed a lobulated mass obscuring the left heart border and abutting the left hilum. Computerized tomography of the chest showed a 9 x 5 cm lobulated left hilar mass obstructing the left upper lobe bronchus and compressing the lower lobe bronchus (Fig 1). Using 18-French fluorodeoxyglucose positron emission tomography (FDGPET) showed no abnormal increased metabolic activity in the mass (Fig 2). Carcinoma embryonic antigen was marginally raised at 9.1 units/mL (reference, <2.5 units/mL). Bronchoscopy revealed a necrotic tumor obstructing the left upper lobe. Biopsy confirmed a thyroid transcription factor-1 negative mucinous adenocarcinoma. At thoracotomy, a large mucinous cystic mass was seen occupying the lingular, extruding along the bronchus, but not involving the upper lobe bronchus. A left upper lobectomy was performed, and the patient made an uneventful recovery. Histologic examination confirmed mucinous adenocarcinoma consistent with a colorectal metastasis (Fig 3).
Positron emission tomography has been shown to be more sensitive than conventional diagnostic imaging for metastatic disease in colorectal cancer [1]. However, in review of 22 patients with a variety of primary or metastatic mucinous carcinomas greater than 1 cm, who underwent FDGPET, increased metabolic activity was shown in only 13 patients, giving a false negative rate of 41%. There was a positive correlation between tumor fluorodeoxyglucose uptake and cellularity, but a negative correlation with mucin content of the tumor [2]. Despite their tendency to be FDGPET negative, paradoxically, mucinous carcinomas of the rectum occur at an advanced stage more frequently than nonmucinous rectal carcinomas, thus having a worse 5-year survival (11% vs 57%) [3]. Although small tumors (<1 cm) and bronchioloalveolar cell carcinomas manifesting as predominantly ground glass opacification on computed tomography are well known to be associated with a lack of metabolic activity on positron emission tomography [4], an understanding of the limitations of FDGPET in mucinous adenocarcinoma is necessary when interpreting positron emission tomographic scans of patients with pulmonary nodules in the context of previous colorectal carcinoma.
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References
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- Berger KL, Nicholson SA, Dehdashti F, Siegel BA. FDG PET evaluation of mucinous neoplasms: correlation of FDG uptake with histopathologic features AJR 2000;174:1005-1008.[Abstract/Free Full Text]
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