Ann Thorac Surg 2009;88:2013-2015. doi:10.1016/j.athoracsur.2009.05.041
© 2009 The Society of Thoracic Surgeons
Case Reports
PEComa (Clear Cell "Sugar" Tumor) of the Lung: A Benign Tumor That Presented With Trombocytosis
Serdar Sen, MDa,
Ekrem Senturk, MDa,*,
Nilgun Kanl
oglu Kuman, MDa,
Engin Pabuscu, MDa,
Firuzan Kacar, MDb
a Department of Thoracic Surgery, Adnan Menderes University, Faculty of Medicine, Aydin, Turkey
b Department of Pathology, Adnan Menderes University, Faculty of Medicine, Aydin, Turkey
Accepted for publication May 13, 2009.
* Address correspondence to Dr Senturk, Adnan Menderes University Medical Faculty, Department of Thoracic Surgeon, Aydin, 09100, Turkey (Email: ekremsenturk{at}hotmail.com).
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Abstract
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Perivascular epithelioid cell tumors of the lung are rare, benign neoplasms, usually presenting as a solitary pulmonary nodule on chest roentgenograms. Most lesions are solitary and asymptomatic, and are located within the peripheral lung. This is a case report of a 44-year-old woman who presented with thrombocytosis and solitary pulmonary nodule of the lung, which was removed by a thoracotomy.
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Introduction
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Perivascular epithelioid cell tumor (PEComa) (Clear cell "sugar" tumor) of the lungs is a rare, pulmonary lesion that was originally described by Liebow and Castleman [1] in 1971. The PEComa usually presents as a solitary pulmonary nodule on a chest roentgenogram [2]. Clinically, PEComa can occur in any age group (range, 8–73 years) with a slight female predominance [3]. Most lesions are solitary and asymptomatic, and are located within the peripheral lung [4]. Histologic perivascular epithelioid cell tumor (PEComa) shows perivascular epithelioid cell differentiation [2].
We believe that there are less than 50 cases of Clear Cell "Sugar" Tumor reported in the English literature [5]. Due to its intense post-contrast enhancement on computed tomographic scans, this tumor may simulate a malignant neoplasm, such as primary or metastatic lung cancer. Histologic and immunohistochemical findings differentiate this tumor from the metastatic renal cell carcinoma [6].
Transthoracic fine-needle biopsy is a valuable diagnostic method of diagnosis, especially in a suspected malignancy, and the performed thoracotomy and segmentectomy were both diagnostic and curative. Although general symptoms such as fever, fatigue, pallor, joint pain, and weight loss are commonly present in patients with some malignancies, they have not been reported in the cases of PEComa [7].
A 44-year-old woman had complaints of headaches and weakness. A physical examination of the patient indicated no abnormalities. From her workup, the laboratory analysis determined that she had a thrombocyte count at 1,000,000 mL. The other laboratory findings and respiratory function tests were normal. The hematology clinic referred her to the chest surgery clinic to evaluate the cause of the thrombocytosis. An intensive search for hematological disorders, such as essential thrombocytosis, was made of the patient. On the chest roentgenogram there was a pulmonary nodule seen with a smooth margin (5 x 5 cm) in the right middle zone. On the thoracic computerized tomography image (Fig 1), the lesion has been described as a peripheral and subpleural (37-mm diameter) nodule, with a smooth and lobulated margin and a solid density of 50 to 75 Hounsfield Units (HU) in the apical segment of the right lung, upper lobe. The radiologic diagnosis was hemangioma, with sclerosis and malignity.
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Fig 1. Thorax tomographic scan shows well-shaped homogeneous, solid lesion in parenchymal and mediastinal windows.
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The patient underwent an operation in which a 5-cm to 6-cm solid mass was palpated in the right upper lobe when the patient underwent the operation. The elastic tumor was reached through a pneumotomy and was enucleated from the lung parenchyma. The tumor weighed 16 g and measured 4 x 3 cm in diameter; the tumor was white in color and had bleeding areas shown in the macroscopic examination (Fig 2A). A rich blood supply was evident in many parts of the tumor.
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Fig 2. (A) Well-shaped tumor measuring 4 x 3 cm shown on macroscopic view. (B, C) Cells were rounded or oval with distinct cell borders and abundant clear cytoplasm microscopically. (Hematoxylin and eosin; x10 and x40, respectively.) (D) Immunohistochemically the tumor cells express human melanoma black (HMB-45). Due to the glycogen rich cytoplasm, there was strong diastase-sensitive. (Periodic acid-Schiff; x40.)
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In the microscopic examination, eosinophilic cytoplasm and diffuse growth pattern were determinate in all sections. Tumor cells staining with periodic acid-Schiff/distaste periodic acid-Schiff positive, with musine negative. Immunohistochemically, these were stained with s100 diffuse and with HMB45 focally (Figs 2B–D). There is no staining with cytoceratin and CD68. The vascular structures are determinate by vimentin and CD34. The histopathologic diagnosis is reported as the clear cell (sugar) tumor of lung (ie, PEComa).
Thrombocyte counts were 853,000 UL, 795,000 mL, and 768,000 UL on postoperative days 2, 4, and 10, respectively. No complication or recurrence occurred in the postoperative follow-up period.
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Comment
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PEComa (clear cell "sugar" tumor) is an unusual, benign, pulmonary tumor that was first described by Liebow and Castleman [1] in 1971, and resembles the renal cell carcinoma both theoretically and practically. Liebow and Castleman [1], reported a study that included 12 cases. There were no significant findings from the physical examinations of their patients, and none of the tumors could be visualized by bronchoscopy. Radiographic visualization revealed that the tumors were rounded or ovoid, smoothly countered, peripheral parenchymal masses. The microscopic appearance through stained sections (by hematoxylin and eosin) was distinctive and rather uniform [1].
The reported cases each presented as a solitary, pulmonary nodule, and all of them were asymptomatic, except only one case that was reported as a mass [4, 8]. The tumor was usually detected accidentally on roentgenogram as a circumscribed peripheral mass [7]. Densitometry measurements should be performed on mediastinal sections to minimize partial-volume effects. These should also be obtained by placing regions of interest to occupy approximately 70% of the short-axis and long-axis dimension of the lung nodule on computed tomographic image [7]. Swensen and colleagues [8] demonstrated 98% sensitivity and 58% specificity for benign results using less than 15 Hounsfield Units (HU) as the maximal amount of enhancement from pre-contrast images. In the study by Swensen and colleagues [9], nodule dimensions ranged between 5 and 40 mm; however, most of the mean diameters of the nodules were greater than 10 mm (mean, 14 mm and 17 mm for benign and malignant nodules, respectively).
Our patient complained of headaches and weakness, and the essential thrombocytosis was defined with the hematologic examination. No pathologic finding was found to explain the cause of thrombocytosis, which can have prognostic significance in lung cancer and is associated with poor outcome in patients with adenocarcinoma and epidermoid cancers [9]. In our case, the thrombocyte count was decreasing regularly after the tumor resection. The level of thrombocyte count was 1,075,000 uL before the operation, and has been dramatically decreased to level of 758,000 uL after the resection on postoperative day ten. Until now, we have not described any PEComa case that had been presented with thrombocytosis in the literature. We believed that the cause of thrombocytosis that had been considered as essential by hematologists was PEComa. We believed that the renal cell tumor could be presented with thrombocytosis, but there was no pathologic finding from the abdominal and pelvic ultrasonography. There was an increase found in thrombocytosis among individuals with ovarian malignancy, with as great as 33% of those with ovarian germ cell tumors demonstrating preoperative thrombocytosis [10].
Definitive diagnosis of PEComa can be obtained by transthoracic tissue biopsy or open biopsy through a thoracotomy. Others have stated that the resection of tumor was enough for the treatment [2, 3, 11]. In our case, the radiologic diagnoses were sclerosing hemangioma and malignancy. The transthoracic biopsy was not advised because of the suspicion of hemangioma. The diagnostic and therapeutic thoracotomy and enucleation were performed after the frozen section was investigated.
Perivascular epithelioid cell tumor of the lung is a benign tumor that is rarely seen, and it would be presented with symptoms such as headaches, weakness, and essential thrombocytosis as with our patient.
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References
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- Liebow AA, Castleman B. Benign clear cell ("sugar") tumors of the lung Yale J Biol Med 1971;43:213-222.[Medline]
- Shimosato Y, Miller RR. Biopsy interpretation of the lungNew York: Raven Press; 1995.
- Folpe AL. Neoplasms with perivascular epithelioid cell differentiation (PEComas)In: Fletcher CD, Unni KK, Mertens F, editors. World health organization classification of tumors. . Pathology and genetics of tumors of soft tissue and bone. Lyon: IARC Press; 2002. pp. 221-222.
- Policarpio-Nicolas ML, Covell J, Bregman J, Atkins K. Fine needle aspiration cytology of clear cell "sugar" tumor (PEComa) of the lung: report of a case Diagn Cytopathol 2005;36:91-93.
- Nguyen GK. Aspiration biopsy cytology of benign clear cell ("sugar") tumor of the lung Acta Cytol 1989;33:511-515.[Medline]
- Santana ANC, Nunes FS, Ho N, Takagaki TY. A rare cause of hemoptisis: benign sugar (clear) cell tumor of the lung Eur J Cardiothorac Surg 2004;25:652-654.[Abstract/Free Full Text]
- Gora-Gebka A, Liberek W, Bako M, Szumera M, Korzon K, Jaskiewicz K. The "sugar" clear cell tumor of the lung—clinical presentation and diagnostic difficulties of an unusual lung tumor in youth J Pediatr Surg 2006;41:27-29.
- Swensen SJ, Morin RL, Schueler BA, et al. Solitary pulmonary nodule: CT evaluation of enhancement with iodinated contrast material—a preliminary report Radiology 1992;182:343-347.[Abstract/Free Full Text]
- Kula O, Bekci TT, Senol T, Pazarli P. Akcigerin iyi Huylu Clear Cell Tumoru Akciger Arsivi 2002;2:67-69.
- Ferrigno D, Buccheri G. Hematologic counts and clinical correlates in 1201 newly diagnosed lung cancer patients Monaldi Arch Chest Dis 2003;59:193-198.[Medline]
- Haddad LB, Laufer MR. Thrombocytosis associated with malignant ovarian lesions within a pediatric/adolescent population J Pediatr Adolesc Gynecol 2008;21:243-246.[Medline]
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Abstract
Introduction
