Ann Thorac Surg 2001;72:2115-2117
© 2001 The Society of Thoracic Surgeons
Case report
Intrapulmonary lymph nodes enlarged after lobectomy for lung cancer
Itaru Nagahiro, MD*a,
Akio Andou, MDa,
Motoi Aoe, MDa,
Hiroshi Date, MDa,
Nobuyoshi Shimizu, MDa
a Department of Surgery II, Okayama University Medical School, Okayama, Japan
Accepted for publication September 26, 2000.
* Address reprint requests to Dr Nagahiro, Department of Surgery II, Okayama University Medical School, 2-5-1 Shikata-cho, Okayama, 700-8558, Japan
e-mail: nagahiro{at}nigeka2.hospital.okayama-u.ac.jp
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Abstract
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A 62-year-old man, who had had a left upper lobectomy for mucoepidermoid lung carcinoma, was admitted again 3 months later because of enlargement of four small nodules in the left lower lobe. A computed tomography–guided needle aspiration biopsy obtained insufficient material for diagnosis, and because pulmonary metastases were suspected, two of the four tumors were extirpated. Intraoperative frozen section found the nodules to be intrapulmonary lymph nodes. Intrapulmonary lymph nodes should be included in the differential diagnosis of coin lesions in the peripheral lung field.
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Introduction
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An intrapulmonary lymph node is a benign nodule that frequently is encounterd, and should be distinguished from a malignant tumor. We describe one in a patient whose intrapulmonary lymph nodes were enlarged after lobectomy for lung cancer, and briefly review the available literature.
A 62-year-old man had had a left upper lobectomy and mediastinal lymph node dissection for a mucoepidermoid carcinoma located in the left upper bronchus on November 18, 1998. Preoperative computed tomography (CT) scan showed some angular, small (3 to 5 mm diameter) nodules located in the subpleural region in the bilateral lungs (Fig 1A). The nodules were so small that they could not be found during the operation, so the operation was followed by CT scan. The mucoepidermoid carcinoma was diagnosed pathologically as low-grade malignancy with no lymph node metastasis. The postoperative course was uneventful and the patient was discharged on December 11, 1998. In February 1999, a follow-up CT scan showed enlargement of the nodules, so the patient was admitted for further examination. Blood cell count and blood chemistry examinations were within normal limits, except for a mild acceleration of the erythrocyte sedimentation rate. Four nodules in the left lower lobe had enlarged to as much as 8 to 12 mm in diameter (Fig 1B). The enlargement was obvious in only the left lower lobe, and the nodules in the right lung remained the same size and shape. A CT-guided needle aspiration biopsy was done on April 2, 1999, and the result was nonspecific inflammation. Although the mucoepidermoid carcinoma that was resected previously was a low-grade malignancy, there was a possibility that the enlarged nodules were intrapulmonary metastases, and the decision was made to resect them. Two were marked with hook wires preoperatively under CT scan. The sixth intercostal space, which was one intercostal space beneath the previous thoracotomy, was opened and a dense adhesion between the chest wall and left lower lobe was encountered. The hook wires were found adjacent to the adhesion, and the nodules were enucleated and sent for intraoperative pathologic examination. The nodules were diagnosed as intrapulmonary lymph nodes (LNs), and the operation was completed, leaving the other nodules. The postoperative course was uneventful.
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Fig 1. (A) Chest computed tomographic scan taken before first operation. Small thin stick-like nodules (arrow) were seen in the subpleural region in the left lower lobe. (B) Chest computed tomographic scan taken 3 months after left upper lobectomy. All nodules in left lower lobe (arrow) were enlarged and had changed into an oval shape.
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Comment
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As the use of high-resolution CT scan and helical CT scan has spread for general investigation, the chance of detecting small nodules in the lung field that had previously gone undetected is increasing. Therefore, the differential diagnosis of such small nodules is becoming more important. Intrapulmonary LNs are one of the important lesions that should be included in the differential diagnosis of small peripheral pulmonary nodules [1].
We resected 13 intrapulmonary LNs in nine patients between 1998 and 2000 (Table 1). All of these intrapulmonary LNs were located at or below the level of the carina, similar to the description by Kradin and colleagues [2]. Seven of nine patients (78%) were heavy smokers. Seven patients had single nodes and two patients had multiple nodes. Nodules were detected in three patients by screening chest x-ray, and others were detected by preoperative or follow-up CT scan for coexisting lung diseases. The diameters ranged from 3 to 13 mm (mean, 6.5 ± 3.0 mm). The characteristics of the resected nodules on high-resolution CT scan were (a) the border was sharp and clear (13 of 13, 100%); (b) the shape was oval (12 of 13, 92.3%); (c) they were located in the subpleural region (range, 0 to 13 mm; mean, 4.0 ± 4.0 mm from visceral pleura), and (d) internal density was high and homogeneous (12 of 13, 92.3%). Five of 13 nodules (38.5%) had some short spicules around them, but no nodules had notches, cavities, or calcifications. Three patients had transbronchial biopsy or CT-guided needle aspiration biopsy, but these techniques did not precisely diagnose the nodules as intrapulmonary LNs.
Nodule growth has been documented in two previous reports [3, 4], over 8 months and 4 years, respectively. The shapes were both oval and did not change so dramatically. In the present case, the shape of the intrapulmonary LNs changed remarkably as they grew from a thin stick-like shape to oval in a period as short as 3 months. Although the reason for the growth of the intrapulmonary LNs is not known in the present case, we suspected that the operation was a triggering mechanism for growth for the following reasons. First, an obstruction of lymphatic ducts by mediastinal lymph node dissection can cause congestion of lymph fluid in the peripheral area, resulting in enlargement of intrapulmonary LNs. Second, postoperative nonspecific inflammatory reaction in the thoracic cavity can extend into lung parenchyma, causing enlargement of intrapulmonary LNs. Interestingly, the same thin sticklike shadows in the right upper lobe, which could also be intrapulmonary LNs, did not change in size and shape, thereby supporting this hypothesis.
Intrapulmonary LNs should be included in the differential diagnosis of small peripheral nodules, because they will be encountered more frequently as the precision of diagnostic systems increases. Although some characteristics of intrapulmonary LNs can be seen on x-rays, it is still hard to distinguish them from small lung cancers; therefore, we should not hesitate to perform thoracoscopic or open biopsy.
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References
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Yokomise H., Mizuno H., Ike O., Wada H., Hitomi S., Itoh H. Importance of intrapulmonary lymph nodes in the differential diagnosis of small pulmonary nodular shadows. Chest 1998;113:703-706.[Abstract/Free Full Text]
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Kradin R.L., Spirn P.W., Mark E.J. Intrapulmonary lymph nodes: clinical, radiologic, and pathologic features. Chest 1985;87:662-667.[Abstract/Free Full Text]
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Houk Z.N., Osborne D.P. Subvisceral pleural lymph node presenting as an expanding intrapulmonary nodule. Am Rev Respir Dis 1965;91:596-599.[Medline]
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Ehrenstein F.I. Pulmonary lymph node presenting as an enlarging coin lesion. Am Rev Respir Dis 1970;101:595-599.[Medline]
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Abstract
Introduction
