Case Study
Thymoma type B1 arising in a giant supradiaphragmatic thymolipoma
Asian Cardiovascular & Thoracic Annals 2014, Vol. 22(9) 1109–1111 ß The Author(s) 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0218492313504576 aan.sagepub.com
Tevfik Kaplan1, Serdar Han1, Unsal Han2, Gokce Kaan Atac3 and Serdar Yanik4
Abstract Thymolipomas are uncommon tumors of the anterior mediastinum. They may extend into, but rarely stem from, the chest cavity. Furthermore, thymoma arising in a thymolipoma is extremely rare. We report a unique case of thymoma type B1 that originated form a giant thymolipoma located in the chest cavity, which was resected by a lateral thoracotomy in a 23-year-old woman. To our knowledge, this is the first reported case of thymoma type B1 arising within a giant thymolipoma.
Keywords Lipoma, Mediastinal neoplasms, Neoplasms, multiple primary, Thymoma, Thymus Neoplasms
Introduction Thymolipoma is a rare, benign tumor of the anterior mediastinum, accounting for 2%–9% of all thymic neoplasms.1,2 Thymolipoma is usually asymptomatic and incidentally identified as a large well-circumscribed mass containing normal thymic parenchyma mixed with mature adipose tissue.2,3 Thymolipomas may sometimes extend into the chest cavity, but extra-mediastinal presentation is extremely rare.3 There have been two cases of type B2 thymoma arising within a thymolipoma;1 but type B1 thymoma in a thymolipoma has not been reported previously in the English literature.
Case report A 23-year-old woman was admitted to the emergency department with thoracic trauma. A chest radiograph and computed tomography of the chest revealed a slightly heterogeneous solid fatty mass next to the right border of the myocardium, 20 to 15 cm in size, with similar density to subcutaneous fat tissue, but there were no findings of acute thoracic injury (Figure 1a). Magnetic resonance imaging of the thorax revealed a hyperintense mass with tiny hypointense septae inside, located between the right lung base and the right diaphragm, best seen on coronal T1-weighted images. Medial and superior extension of the mass
dissected the space between the medial part of the right lung and the right border of the heart, and traveled proximally until the mid part of the mediastinum (Figure 1b). Total mass excision was performed via a right lateral thoracotomy after reaching a preoperative diagnosis of intrathoracic lipoma or diaphragmatic hernia (Figure 2a). An intraoperative frozen section procedure on the soft, fatty, and well-encapsulated mass, without evidence of invasion into the surrounding tissue, confirmed the diagnosis of a benign lesion, thus no additional surgery was performed. Macroscopic investigation of the excised mass, weighing 1485 g and measuring 20 15 3 cm, surrounded by a thin fibrous capsule (Figure 2b), revealed a circumscribed firm
1 Department of Thoracic Surgery, Ufuk University School of Medicine, Ankara, Turkey 2 Department of Pathology, Diskapi Yildirim Beyazit Teaching and Research Hospital, Ankara, Turkey 3 Department of Radiology, Ufuk University School of Medicine, Ankara, Turkey 4 Department of Pathology, Iskenderun State Hospital, Hatay, Turkey
Corresponding author: Tevfik Kaplan, MD, Department of Thoracic Surgery, Ufuk University School of Medicine, Dr. Ridvan Ege Teaching and Research Hospital, Mevlana Bulvarı (Konya Yolu) No: 86-88, 06520 Balgat, Ankara, Turkey. Email: [email protected]
Downloaded from aan.sagepub.com at CARLETON UNIV on May 11, 2015
1110
Asian Cardiovascular & Thoracic Annals 22(9)
Figure 1. (a) Computed tomography of the thorax showing a heterogeneous solid mass, 20 to 15 cm in size, with similar density to subcutaneous fat tissue, next to the border of the heart. (b) T1-weighted coronal magnetic resonance image of the thorax showing medial and superior extension of the mass that dissected the space between the medial part of the right lung and right border of the heart, and traveled proximally up to the anterior mediastinum.
Figure 2. (a) Intraoperative view of the mass. (b) The mass was soft, fatty, and well-encapsulated without evidence of invasion into the surrounding tissue. (c) Microscopic findings revealed mature fatty tissue and thymic tissue structures. Hematoxylin and eosin stain, original magnification 40. (d) Histopathological examination of sections from the firm mass showed proliferation of epithelial cells without atypia, among abundant lymphocytes, resembling thymic tissue. Hematoxylin and eosin stain, original magnification 200.
grayish mass measuring 7 3 cm at one pole upon sectioning. Microscopic images from the main mass showed mature fatty tissue harboring scattered foci of unremarkable thymic tissue, consistent with thymolipoma (Figure 2c). Sections of the firm mass stained with hematoxylin and eosin revealed proliferation of inconspicuous epithelial cell with no atypia, in a lymphocyte-rich background, resembling thymic tissue without capsular invasion (Figure 2d). The second tumor inside the thymolipoma was classified as a type BI and stage I thymoma according to World Health Organization criteria
and the Masaoka clinical staging system.4,5 Follow-up imaging studies for 2 years have not revealed any recurrence.
Discussion As a rare benign tumor of the thymus gland, thymolipoma is usually asymptomatic and incidentally discovered as a large well-circumscribed anterior mediastinal mass containing fat and thymic tissue, in patients with an age range of 3 to 76 years, without a
Downloaded from aan.sagepub.com at CARLETON UNIV on May 11, 2015
Kaplan et al.
1111
gender difference.1,2 Extra-mediastinal presentation of thymolipomas is extremely rare.3 In this case, the mass was unusually supradiaphragmatic in the right hemithorax, extending into the mediastinum. Thymolipoma can be misinterpreted as a pericardial effusion, atelectasis, sequestration, lipoma, or cardiomegaly on radiographic investigations. Chest computed tomography and/or magnetic resonance imaging are usually diagnostic, showing a mixture of soft tissue and fat in the lesion.2,3 In our case, there was no invasion into the surrounding structures, and the preoperative diagnosis based on imaging studies was intrathoracic lipoma or diaphragmatic hernia. We found only 2 case reports in the English literature of thymoma type B2 within a thymolipoma.1 Our patient is the third case of thymoma arising in a thymolipoma; however, thymoma type B1 arising in a giant thymolipoma has not been reported previously. The histopathological view of type B1 thymoma, with a relatively better prognosis, can be confused with B2 thymoma; both may have abundant lymphocytes and a few epithelial cells, but type B1 has numerous scattered pale medullary foci, which are not found in type B2.5 Surgical removal of the thymolipoma is curative as recurrence is not seen following surgery if complete resection is performed.3 A 4% recurrence rate of stage I thymomas after surgery has been described, even after complete resection.6 Although a completion thymectomy appeared to be justified in this patient, the recommendation of a second operation, because the literature demonstrates the multicentric nature of thymomas, was refused.4,6 We have followed up this case
with annual computed tomography imaging for an uneventful two years. Funding This research received no specific grant from any funding agency in the public, commerical, or not-for-profit sectors.
Conflict of interest statement None declared.
References 1. Haddad H, Joudeh A, El-Taani H, et al. Thymoma and thymic carcinoma arising in a thymolipoma: report of a unique case. Int J Surg Pathol 2009; 17: 55–59. 2. Thingnam SK, Puri D, Jha N, Vasishta RK and Suri RK. Thymolipoma of the anterior mediastinum. Asian Cardiovasc Thorac Ann 1999; 7: 62–4. (Available at: http://aan.sagepub.com/content/7/1/62.full.pdfþhtml. Accessed August 20, 2013. 3. Damadoglu E, Salturk C, Takir HB, et al. Mediastinal thymolipoma: an analysis of 10 cases. Respirology 2007; 12: 924–927. 4. Masaoka A, Monden Y, Nakahara K and Tanioka T. Follow-up study of thymomas with special reference to their clinical stage. Cancer 1981; 48: 2485–2492. 5. Kim DJ, Yang WI, Choi SS, Kim KD and Chung KY. Prognostic and clinical relevance of the World Health Organization schema for the classification of thymic epithelial tumors: a clinicopathologic study of 108 patients and literature review. Chest 2005; 127: 755–761. 6. Blumberg D, Port JL, Weksler B, et al. Thymoma: a multivariate analysis of factors predicting survival. Ann Thorac Surg 1995; 60: 908–913.
Downloaded from aan.sagepub.com at CARLETON UNIV on May 11, 2015
Thymoma type B1 arising in a giant supradiaphragmatic thymolipoma
Asian Cardiovascular & Thoracic Annals 2014, Vol. 22(9) 1109–1111 ß The Author(s) 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav DOI: 10.1177/0218492313504576 aan.sagepub.com
Tevfik Kaplan1, Serdar Han1, Unsal Han2, Gokce Kaan Atac3 and Serdar Yanik4
Abstract Thymolipomas are uncommon tumors of the anterior mediastinum. They may extend into, but rarely stem from, the chest cavity. Furthermore, thymoma arising in a thymolipoma is extremely rare. We report a unique case of thymoma type B1 that originated form a giant thymolipoma located in the chest cavity, which was resected by a lateral thoracotomy in a 23-year-old woman. To our knowledge, this is the first reported case of thymoma type B1 arising within a giant thymolipoma.
Keywords Lipoma, Mediastinal neoplasms, Neoplasms, multiple primary, Thymoma, Thymus Neoplasms
Introduction Thymolipoma is a rare, benign tumor of the anterior mediastinum, accounting for 2%–9% of all thymic neoplasms.1,2 Thymolipoma is usually asymptomatic and incidentally identified as a large well-circumscribed mass containing normal thymic parenchyma mixed with mature adipose tissue.2,3 Thymolipomas may sometimes extend into the chest cavity, but extra-mediastinal presentation is extremely rare.3 There have been two cases of type B2 thymoma arising within a thymolipoma;1 but type B1 thymoma in a thymolipoma has not been reported previously in the English literature.
Case report A 23-year-old woman was admitted to the emergency department with thoracic trauma. A chest radiograph and computed tomography of the chest revealed a slightly heterogeneous solid fatty mass next to the right border of the myocardium, 20 to 15 cm in size, with similar density to subcutaneous fat tissue, but there were no findings of acute thoracic injury (Figure 1a). Magnetic resonance imaging of the thorax revealed a hyperintense mass with tiny hypointense septae inside, located between the right lung base and the right diaphragm, best seen on coronal T1-weighted images. Medial and superior extension of the mass
dissected the space between the medial part of the right lung and the right border of the heart, and traveled proximally until the mid part of the mediastinum (Figure 1b). Total mass excision was performed via a right lateral thoracotomy after reaching a preoperative diagnosis of intrathoracic lipoma or diaphragmatic hernia (Figure 2a). An intraoperative frozen section procedure on the soft, fatty, and well-encapsulated mass, without evidence of invasion into the surrounding tissue, confirmed the diagnosis of a benign lesion, thus no additional surgery was performed. Macroscopic investigation of the excised mass, weighing 1485 g and measuring 20 15 3 cm, surrounded by a thin fibrous capsule (Figure 2b), revealed a circumscribed firm
1 Department of Thoracic Surgery, Ufuk University School of Medicine, Ankara, Turkey 2 Department of Pathology, Diskapi Yildirim Beyazit Teaching and Research Hospital, Ankara, Turkey 3 Department of Radiology, Ufuk University School of Medicine, Ankara, Turkey 4 Department of Pathology, Iskenderun State Hospital, Hatay, Turkey
Corresponding author: Tevfik Kaplan, MD, Department of Thoracic Surgery, Ufuk University School of Medicine, Dr. Ridvan Ege Teaching and Research Hospital, Mevlana Bulvarı (Konya Yolu) No: 86-88, 06520 Balgat, Ankara, Turkey. Email: [email protected]
Downloaded from aan.sagepub.com at CARLETON UNIV on May 11, 2015
1110
Asian Cardiovascular & Thoracic Annals 22(9)
Figure 1. (a) Computed tomography of the thorax showing a heterogeneous solid mass, 20 to 15 cm in size, with similar density to subcutaneous fat tissue, next to the border of the heart. (b) T1-weighted coronal magnetic resonance image of the thorax showing medial and superior extension of the mass that dissected the space between the medial part of the right lung and right border of the heart, and traveled proximally up to the anterior mediastinum.
Figure 2. (a) Intraoperative view of the mass. (b) The mass was soft, fatty, and well-encapsulated without evidence of invasion into the surrounding tissue. (c) Microscopic findings revealed mature fatty tissue and thymic tissue structures. Hematoxylin and eosin stain, original magnification 40. (d) Histopathological examination of sections from the firm mass showed proliferation of epithelial cells without atypia, among abundant lymphocytes, resembling thymic tissue. Hematoxylin and eosin stain, original magnification 200.
grayish mass measuring 7 3 cm at one pole upon sectioning. Microscopic images from the main mass showed mature fatty tissue harboring scattered foci of unremarkable thymic tissue, consistent with thymolipoma (Figure 2c). Sections of the firm mass stained with hematoxylin and eosin revealed proliferation of inconspicuous epithelial cell with no atypia, in a lymphocyte-rich background, resembling thymic tissue without capsular invasion (Figure 2d). The second tumor inside the thymolipoma was classified as a type BI and stage I thymoma according to World Health Organization criteria
and the Masaoka clinical staging system.4,5 Follow-up imaging studies for 2 years have not revealed any recurrence.
Discussion As a rare benign tumor of the thymus gland, thymolipoma is usually asymptomatic and incidentally discovered as a large well-circumscribed anterior mediastinal mass containing fat and thymic tissue, in patients with an age range of 3 to 76 years, without a
Downloaded from aan.sagepub.com at CARLETON UNIV on May 11, 2015
Kaplan et al.
1111
gender difference.1,2 Extra-mediastinal presentation of thymolipomas is extremely rare.3 In this case, the mass was unusually supradiaphragmatic in the right hemithorax, extending into the mediastinum. Thymolipoma can be misinterpreted as a pericardial effusion, atelectasis, sequestration, lipoma, or cardiomegaly on radiographic investigations. Chest computed tomography and/or magnetic resonance imaging are usually diagnostic, showing a mixture of soft tissue and fat in the lesion.2,3 In our case, there was no invasion into the surrounding structures, and the preoperative diagnosis based on imaging studies was intrathoracic lipoma or diaphragmatic hernia. We found only 2 case reports in the English literature of thymoma type B2 within a thymolipoma.1 Our patient is the third case of thymoma arising in a thymolipoma; however, thymoma type B1 arising in a giant thymolipoma has not been reported previously. The histopathological view of type B1 thymoma, with a relatively better prognosis, can be confused with B2 thymoma; both may have abundant lymphocytes and a few epithelial cells, but type B1 has numerous scattered pale medullary foci, which are not found in type B2.5 Surgical removal of the thymolipoma is curative as recurrence is not seen following surgery if complete resection is performed.3 A 4% recurrence rate of stage I thymomas after surgery has been described, even after complete resection.6 Although a completion thymectomy appeared to be justified in this patient, the recommendation of a second operation, because the literature demonstrates the multicentric nature of thymomas, was refused.4,6 We have followed up this case
with annual computed tomography imaging for an uneventful two years. Funding This research received no specific grant from any funding agency in the public, commerical, or not-for-profit sectors.
Conflict of interest statement None declared.
References 1. Haddad H, Joudeh A, El-Taani H, et al. Thymoma and thymic carcinoma arising in a thymolipoma: report of a unique case. Int J Surg Pathol 2009; 17: 55–59. 2. Thingnam SK, Puri D, Jha N, Vasishta RK and Suri RK. Thymolipoma of the anterior mediastinum. Asian Cardiovasc Thorac Ann 1999; 7: 62–4. (Available at: http://aan.sagepub.com/content/7/1/62.full.pdfþhtml. Accessed August 20, 2013. 3. Damadoglu E, Salturk C, Takir HB, et al. Mediastinal thymolipoma: an analysis of 10 cases. Respirology 2007; 12: 924–927. 4. Masaoka A, Monden Y, Nakahara K and Tanioka T. Follow-up study of thymomas with special reference to their clinical stage. Cancer 1981; 48: 2485–2492. 5. Kim DJ, Yang WI, Choi SS, Kim KD and Chung KY. Prognostic and clinical relevance of the World Health Organization schema for the classification of thymic epithelial tumors: a clinicopathologic study of 108 patients and literature review. Chest 2005; 127: 755–761. 6. Blumberg D, Port JL, Weksler B, et al. Thymoma: a multivariate analysis of factors predicting survival. Ann Thorac Surg 1995; 60: 908–913.
Downloaded from aan.sagepub.com at CARLETON UNIV on May 11, 2015
