| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
|
Interact CardioVasc Thorac Surg 2007;6:676-678. doi:10.1510/icvts.2007.154039 © 2007 European Association of Cardio-Thoracic Surgery
Pecoma of the lung: a benign tumor with extensive 18F-2-deoxy-D-glucose uptake
a Department of Thoracic Surgery, 251 General Hospital of the Hellenic Air Force, Athens, Greece Received 16 February 2007; received in revised form 2 May 2007; accepted 21 May 2007
*Corresponding author. Universitätsklinik für Thorax- und Gefässchirurgie, Universität Ulm, Steinhövelstrasse 9, 89075 Ulm, Germany. Tel.: +49 731/500-27301; fax: +49 731/500-27289.
A case of lung pecoma (i.e. tumors showing perivascular epithelioid cell differentiation) with extensive 18F-2-deoxy-D-glucose (FDG) uptake in PET/CT study is reported. Pecomas of the lung – which include the better known clear cell ‘sugar’ tumor – are a subset of extremely rare lung tumors which usually react positively to both melanocytic and smooth muscle markers. Although widely presumed as benign in computed tomography (CT) and positron emission tomography (PET)/CT studies they depict as malignant, thus complicating the preoperative diagnosis. A subset of pecomas could conceal a malignant potential.
Key Words: Lung tumor; Positron emission tomography
A 71-year-old female smoker presented to her family doctor with vague pain over the left hemithorax radiating to the neck. Physical exam and laboratory results were unremarkable, except for arterial hypertension. The chest radiographs showed a well demarcated round mass in the left lower lobe and a CT scan confirmed the existence of a round uniform mass of ca. 2.8 cm in the left lower lobe which presented post-contrast enhancement and that had increased in size compared to a previous CT five years before. The patient was reluctant at that time to proceed to any further investigation of the mass and because of the abscense of objective symptoms within those five years she followed no follow-up protocol. Bronchoscopy failed to detect signs of endobronchial tumor and bronchial washings were negative for both microorganisms and malignancy. Given the increased number of false negative results for so small lesions, we succumbed to the patient's wish not to undergo percutaneous CT-guided needle biopsy of the mass, which is our standard practice, and proceeded straight to PET/CT which revealed a well demarcated lobulated round-like mass in the apical segment (S6) of the left lower lobe, with dimensions of 2.9x2.8 in ‘pulmonary window’ and 2.5x2.2 in ‘ostial window’, with extensive 18FDG uptake (Fig. 1). No other pulmonary, mediastinal, cervical, intra- or retro-abdominal focus of increased FDG uptake was depicted. Lymph nodes were unremarkable in all regions. The patient was then referred to us for further treatment.
In the preoperative work-up normal cardiac function but severe COPD were constituted. An S6 segmentectomy was carried out through an open thoracotomy. Grossly the tumor was 2.5 cm in diameter, gray-whitish and well demarcated from the surrounding lung parenchyma. The visceral pleura was intact. The tumor consisted of round or oval epithelioid cells with eosinophilic cytoplasm. The tumor was strongly positive to PAS sensitive-diastase, HMB-45, Vimentin and CD34, while c-Kit, S-100, Cytokeratin, Myosin, Actin and CD99 were not expressed, showed no signs of necrosis and had a mitotic activity of <1 per 1000 (Ki-67 score) (Fig. 2). Thus, it was defined as a benign clear cell tumor of the lung (CCTL) or as a pecoma of the lung and no further treatment was implemented or suggested, other than routine follow-up. The postoperative course was surprisingly free of major complications and the patient was discharged on the 8th postoperative day. The patient is alive and well, one year after the operation.
Pecomas are a group of mesenchymal neoplasms that incorporates angiomyolipoma, lymphagiomyomatosis, CCTL and a set of similar visceral and soft tissue lesions that are all characterized by the ‘perivascular epithelioid cell’ [1]. CCTL shows no particular sexual predominance. Patients range from 8 to 73 years of age. As CCTL usually presents as an asymptomatic solitary pulmonary nodule, they pose a significant diagnostic problem. Only two cases thus far have evidently presented themselves with hemoptysis, and the complaints of our patient were unrelated to the CCTL that was finally discovered [2]. CCTL radiographically presents as a round, peripheral, parenchymal nodule with no evidence of cavitation or calcification. In CT, it can show intense post-contrast enhancement, attributed to its rich vascular stroma, and only in one report a diagnosis could be achieved through transbronchial lung biopsy [2–4]. Our finding of extensive 18FDG-uptake in PET/CT, which to the best of our knowledge is being reported for the first time, comes to complicate preoperative diagnosis even further. Positive 18FDG study in patients over 60 years of age points to malignancy with a probability of 90% [5]. The sensitivity, specificity and accuracy of PET/CT to differentiate a malignant from a benign lesion are 96%, 88% and 94%, respectively, in lesions as small as 10 mm [6]. According to the above, coupled with the post-contrast enhancement on CT and the slow – but nevertheless existing – growth over five years, one could presume a concealed malignancy in our case. On the other hand, our patient presented severe COPD (FEV1=0.68 l, FVC=1.6 l, pO2=66.9) unaffected by respiratory exercise and bronchodilators, thus precluding a lobectomy. Therefore, we proceeded with segmentectomy and abstained from fast histological examination, as technically and physiologically an atypical resection would equal segmentectomy and the result of the fast examination could not exclude 100% a malignant potential. The proposals for the origin of CCTL have included over the years the pericytic or smooth muscle cell, the Kulchitsky cell, the Clara cell and lately the ‘perivascular epithelioid cell’ [1, 7]. CCTL should be distinguished from clear cell carcinoid of the lung, metastatic renal cell carcinoma, metastatic melanoma, granular cell tumors, oncocytoma and acinic cell tumor [7, 8]. CCTL is traditionally considered benign, with only one argued report of fatal recurrence and metastasis [9, 10]. Nevertheless, Gaffey et al. advocate that CCTL with a diameter of 2.5 cm and necrosis should be considered as a potentially metastasizing neoplasm [7, 9]. Necrosis, mitotic index of 1 per 50 high-power fields, marked pleomorphism and nuclear atypia could also point to a malignant potential [1]. According to WHO directives, excision is the treatment of choice and no other adjuvant therapy is recommended [8]. The extent of the excision is still a matter of debate between surgeons. We believe that a lung preserving resection with tumor-free margins is sufficient for this tumor.
We would like to thank Prof. Dr. med Karl H. Orend and Prof. Dr. med Ludger Sunder-Plassmann of University Ulm, Germany for providing us with their experience on how to deal with this unusual case and for reviewing the article.
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| ANN THORAC SURG | ASIAN CARDIOVASC THORAC ANN | EUR J CARDIOTHORAC SURG |
| J THORAC CARDIOVASC SURG | ICVTS | ALL CTSNet JOURNALS |
Top
Abstract
1. Case report
red arrow, left figure, soft tissue windowing) In the lung window (left figure below) lobulated uniform mass with dimensions of 2.9 cmx 2.8 cm, surrounding lung parenchyma was normal. In the axial slice of positron emissions tomography (PET) using fluorine-18-2-deoxy-2-fluoro-D-glucose (FDG) focal FDG-uptake with a SUV mean of 1.9 and SUV max of 2.0 was measured. Integrated fused PET/CT slice visualized focal FDG-uptake in the middle of the tumor.