Ann Thorac Surg 2009;87:956-957. doi:10.1016/j.athoracsur.2008.07.078
© 2009 The Society of Thoracic Surgeons
Case Reports
A Small Alveolar Adenoma Resected by Thoracoscopic Surgery
Hiroshige Nakamura, MD*,
Yoshin Adachi, MD,
Takayuki Arai, MD,
Ken Miwa, MD,
Tomohiro Haruki, MD,
Shinji Fujioka, MD,
Yuji Taniguchi, MD
Division of General Thoracic Surgery, Center for Clinical Residency Program, Tottori University Hospital, Yonago, Japan
Accepted for publication July 25, 2008.
* Address correspondence to Dr Nakamura, Division of General Thoracic Surgery, Tottori University Hospital, 36-1 Nishi-cho, Yonago, Tottori, 683-8504, Japan (Email: hnaka{at}med.tottori-u.ac.jp).
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Abstract
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Alveolar adenoma (AA) is a rare lung benign tumor originated from type II pneumocytes. It presents as a well-defined nodule in clinical images, but is difficult to differentiate from early-stage lung cancer. We treated a 58-year-old woman with a small-sized AA measuring 8 x 6 mm in the upper lobe of the left lung by performing a thoracoscopic resection. The AA does not cause any symptoms and it is often incidentally detected as an abnormal shadow. There have been no reported cases of recurrence after a resection of AA, but a subsequent increase in such cases is expected, and we believe that it is necessary to understand the characteristics of this typical benign lung tumor.
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Introduction
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Alveolar adenomas (AA) have been found in only 27 cases in the English medical literature. It is a highly rare benign lung tumor, but it is difficult to differentiate from small early-stage lung cancer. We experienced a case presenting with an AA measuring 8 mm in diameter, which we believe is the smallest size ever reported, and we describe its histologic characteristics with bibliographical considerations.
The case was a 58-year-old woman who was found to have an abnormality in the nasal cavity when she visited a local physician with a complaint of a common cold, and she underwent a detailed examination to rule out Wegener's granuloma. A chest computed tomographic image revealed a well-defined nodule measuring slightly less than 10 mm in diameter in the lingua of the upper lobe of the left lung (Fig 1A). There were no abnormal findings in a blood test. The patient's history of disorders included pacemaker insertion due to a complete atrioventricular block. The possibility of malignancy could not be ruled out from the image findings and Wegener's granulomatosis was also suspected; therefore, a thoracoscopic partial lung resection was performed. The tumor measured 8 x 6 mm in size, was solid and was well-defined from the periphery (Fig 1B). A histopathologic examination (Figs 2A and 2B) revealed cells with substantially round nuclei and columnar cytoplasms growing in a tubular manner. Atypia of the nuclei was mild and there were no indications of nuclear division. In immunohistochemical staining, the tumor cells were positive for cytokeratin 7, surfactant appoprotein A, and thyroid transcriptase factor-1, and were negative for cytokeratin 20. The mindbomb homolog-1 (MIB-1) positive rate was less than 1%. The patient was diagnosed to have an AA originated from type II alveolar epithelial cells. The postoperative course was good and there has been no recurrence during the 3-month postoperative follow-up.
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Fig 1. (A) Chest computed tomographic scan showed a small, well-defined nodule in the left upper lobe. (B) The resected specimen showed a small and well-defined solid nodule (arrow).
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Fig 2. (A) Pathologic findings with hematoxylin and eosin staining showed well-demarcated, multi-cystic tumors in the low power field (original magnification, x4). (B) Cells with substantially round nuclei and columnar cytoplasms growing in a tubular manner in the high-power field (original magnification, x200).
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Comment
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The AA was first reported by Yousem and Hochholzer [1] in 1986. It is identified with clinical images as a well-defined nodule in the peripheral lung, and we found it has been reported in only 27 cases in the English medical literature [1–6], but it is also possible that there have been cases in which it was misidentified as a similar disease; therefore an accurate rate of occurrence remains to be determined. Sak and colleagues [6] reviewed the past reported cases and described that AA occurs most often in the middle and lower lobes of middle-aged and older female patients. There was only 1 case of multiple occurrences and the sizes ranged from 10 mm to 60 mm, with the 8-mm diameter seen in our case being the smallest reported size. The pathologic characteristics mainly include the growth of type II alveolar epithelial cells with no signs of nuclear division or cell necrosis [1–4, 6]. Differential diagnoses such as sclerosing hemangioma and papillary adenoma for cases of benign tumor or atypical adenomatous hyperplasia and bronchio-alveolar carcinoma for cases of malignancy are often problematic. In particular, sclerosing hemangioma is characterized by a polymorphic histologic appearance with a mixture of solid, vascular, and sclerotic and papillary patterns [6], which is different from the progression of AA that occurs along the alveolar structure. In addition, the expression of thyroid transcriptase factor-1, which was positive in our case, has also been reported to be important for differentiation purposes [6]. A preoperative diagnosis and intraoperative pathologic diagnosis of AA are often difficult [5], and a diagnosis can often only be confirmed after a resection, but fortunately, there have been no cases of recurrence after a resection [1, 3, 4, 6]. Although the progression of AA is very similar to those of atypical adenomatous hyperplasia or bronchio-alveoral carcinoma, the cell images are clearly different, because AA showed a diploid cell pattern based on the findings of a flow cytometry analysis and the mindbomb homolog-1 (MIB-1) positive rate is less than 1% [6]. The AA has thus far been considered to be a rare disease, but it is possible that the number of detected cases will gradually increase as progress is made in diagnostic imaging, and we believe there is a need to be aware of its characteristics as a benign tumor.
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References
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- Yousem SA, Hochholzer L. Alvelar adenoma Hum Pathol 1986;17:1066-1071.[Medline]
- Semeraro D, Gibbs AR. Pulmonary adenoma: a variant of sclerosing haemangioma of lung? J Clin Pathol 1989;42:1222-1227.[Free Full Text]
- Bruke LM, Rush WI, Khoor A, et al. Alveolar adnoma: a histochemical, immunohistochemical, and ultrastructural analysis of 17 cases Hum Pathol 1999;30:158-167.[Medline]
- Cakan A, Samancilar O, Nart D, Cagirici U. Alveolar adenoma:an usual lung tumor Interact Cardiovasc Thorac Surg 2003;2:345-347.[Abstract/Free Full Text]
- Hartman MS, Epstein DM, Geyer SJ, Keenan RJ. Alveolar adenoma Ann Thorac Surg 2004;78:1842-1843.[Abstract/Free Full Text]
- Sak SD, Koseoglu RD, Demirag F, Akbulut H, Gungor A. Alveolar adenoma of the lung. Immunohistochemical and flow cytometric characteristics of two new case and review of the literature. APMIS 2007;115:1443-1449.[Medline]
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Abstract
Introduction
