Case Report
Giant thymolipoma in an infant Ankit Parakh1, Varinder Singh1, R. Subramaniam1, Mahender Kaur Narula2, Surendra Kumar Agarwala3, Shailaja Shukla4 Departments of 1Pediatrics, 2Radiology, 3Pediatric Surgery and 4Pathology, Lady Hardinge Medical College and Kalawati Saran Children’s Hospital, New Delhi, India Thymolipomas are benign neoplasms that usually occur in adults and are rarely described in children. They are usually detected incidentally but can be of massive size and lead to respiratory compromise. A 6month-old boy presented with respiratory distress and an anterior mediastinal mass which proved to be a thymolipoma. He underwent surgical resection and remains well on follow-up. Although rare, thymolipomas should be considered in the differential diagnosis even in infants presenting with an anterior mediastinum mass. Keywords: Anterior mediastinal mass, Infant, Thymolipoma
Introduction Thymolipoma is a rare benign anterior mediastinal tumor mainly limited to adults.1–6 It is usually asymptomatic, but can enlarge significantly prior to diagnosis and can cause significant symptoms.7–9 A 6month-old boy presented with respiratory distress which was found to be caused by a giant thoracic thymolipoma.
Case Report A 6-month-old boy presented to Kalawati Saran children’s hospital with rapid breathing for the previous 3 months. There was no associated fever, cough or difficulty in feeding. He was born at term, was developmentally normal and appropriately immunised for his age. On examination, the heart rate was 136/min, respiratory rate 66/min, and there were mild intercostal and subcostal retractions. He was otherwise alert and active. His weight was 6.4 kg (3rd centile), length 66 cms (25th centile), and his weight-for-length was ,3rd centile. Pulse oximetry showed a saturation of 95% in room air. There was no significant lymphadenopathy. Chest examination demonstrated tracheal shift to the right side and the cardiac apex was shifted to the right. Breath sounds were reduced on the left side with an impaired percussion note. Heart sounds were heard better over the right hemithorax. S1 and S2 heart sounds were normal with no murmurs. There were no features of superior vena cava obstruction. Abdomen examination was normal with no hepatosplenomegaly. The remainder of the examination was normal.
Investigations. Complete blood count, renal and liver function tests, uric acid and serum lactate dehydrogenase levels were within normal limits. A chest radiograph demonstrated a homogenous opacity involving the entire left hemithorax with collapse of the lower lobe of the left lung and a marked mediastinal shift (Fig. 1a). The right lung appeared normal. A contrast-enhanced CT of the thorax showed a large heterogeneous mass with fat tissue density occupying the entire left hemithorax with extensions into the anterior mediastinum and partially into the right hemithorax, along with mediastinal shift and atelectasis of the surrounding lung tissue (Fig. 1b). There was no infiltration into the pericardium, chest wall or diaphragm. An echocardiogram was normal. An ultrasound-guided tru-cut biopsy was undertaken in the left anterior axillary line in the third intercostal space. Histopathological examination of the biopsy specimen deonstrated an admixture of mature adipose tissue and normal thymic tissue with Hassal’s corpuscles consistent with thymolipoma (Fig. 1c). A left anterior thoracotomy demonstrated a large mass occupying the left thoracic cavity and the anterior mediastinum with no evidence of any pericardial, vascular or hilar invasion. When excised, itt weighed 840 g (Fig. 1d). Histopathology confirmed a large multifocal thymolipoma. The child made a rapid and uneventful recovery. He was discharged 1 week after surgery and remains well under follow-up for the last year.
Discussion Correspondence to: A Parakh, Department of Pediatrics, Lady Hardinge Medical College and Kalawati Saran Children’s Hospital, New Delhi – 110001, India. Email: [email protected]
230
ß W. S. Maney & Son Ltd 2014 DOI 10.1179/2046905513Y.0000000108
Thymolipoma is a rare, well encapsulated, benign anterior mediastinal tumour which was first reported
Paediatrics and International Child Health
2014
VOL.
34
NO.
3
Parakh et al.
Figure 1 (A): Chest radiograph demonstrating a homogeneous mass in the left hemithorax; (B) Contrast CT of thorax showing the anterior mediastinum with an extensive fat component (arrow); (C) Photomicrograph (H&E 610) showing an admixture of adipocytes (arrow) with thymus tissue (arrow head); inset demonstrating Hassal’s corpuscles (arrow); (D) Gross appearance showing a lobulated pink/ yellow mass weighing 840 g
by Lange in 1916.1 Lange described it as a lipoma of the thymus; however, the term ‘thymolipoma’ was used first by Hall in 1948.2 Overall, thymic neoplasms comprise only 4% of all mediastinal tumours in children,3 and only 2–9% of these are reported to be thymolipomas.4,5 The ages of patients range from 2 to 64 years (mean 33) with no gender predilection.6 A thorough search of the literature using PubMed found very few cases in the paediatric population6–9 and no case reported in infancy. The youngest case in the literature was 2 years old.6 Thymolipomas usually run an indolent, asymptomatic course, with most cases discovered incidentally as huge anterior mediastinal masses on chest roentgenogram. The tumour can enlarge, mould and accommodate in the thoracic cavity, often achieving massive dimensions before presentation. In most cases they weigh more than 500 g with 25% weighing more than 2000 g and the largest size reported in the literature being 6000 g.10 The mass can be very large, as in our case (840 g in a 6.4-kg infant 13% of bodyweight) and can lead to respiratory compromise or failure.11 In adults, thymolipoma is known to be associated with other diseases such as myasthenia gravis,12 cystic lymphangioma13 and Graves’ disease,14 although none of these were present in our case. On routine chest radiograph, the tumour may appear as a sharply circumscribed mediastinal density simulating cardiomegaly, pericardial effusion or a pericardial tumour.15 The CT and MRI appearance of thymolipoma is characteristic and is very helpful in diagnosing anterior mediastinum lesions, especially thymic masses. On thoracic CT, the tumour appears as linear strands and whorls of soft tissue intermixed
Infantile thymolipoma
with fat or as rounded islands of soft tissue surrounded by fat.16 On MRI, the adipose tissue within the tumour appears iso-intense in T1-weighted images whereas it remains suppressed in T2-weighted images, when the remainder of the thymic tissue is enhanced.16 The pathogenesis of thymolipoma is controversial. Replacement of diffuse thymic hyperplasia by adipose tissue seems to be the most widely accepted explanation.10 It has also been suggested that both thymic and fatty tissue are neoplastic and contribute equally to the development of the thymolipoma.2 Recent reports also suggest that thymolipoma is a neoplasm of thymic fat with translocation involving the HMGA2 gene on chromosome 12q15.17 Owing to the small number of cases in the literature, there are no clear recommendations on the best management of thymolipomas. In patients presenting with respiratory distress (as in this case), surgical resection of the tumour is required and is curative. Whether small lesions detected incidentally can be managed conservatively is still unclear. Spontaneous involution of the tumour has not been described. Although benign, thymolipomas have rarely been associated with malignancies such as thymic carcinoid tumours,18 thymomas and thymic carcinomas.19 Variants such as thymofibrolipomas,21 thymoliposarcomas21 and thymohaemangiolipoma22 have also been described. Hence, it is justified to consider a biopsy in all cases even with characteristic imaging. In view of its associations such as with myasthenia gravis, immune disorders, unusual variants and a small risk of malignancy, surgery should be considered in all cases. The above associations have been reported in adults only. The encapsulated nature of thymolipomas and lack of invasion into adjacent structures allows for relatively uncomplicated surgical excision of the tumour.23 Recurrences have not been reported. This case highlights the occurrence of a rare tumour which usually affects adults but can occur as early as in infancy.
References 1 Lange L. Uberein Lipom des Thymus [A lipoma of the thymus]. Zentralbl Allg Pathol. 1916;27:97–101. 2 Hall GFM. A case of thymolipoma with observations on a possible relationship to intrathoracic lipomata. Br J Surg. 1948;36:321–4. 3 Takeda S, Miyoshi S, Akashi A, Ohta M, Minami M, Okumura M, et al. Clinical spectrum of primary mediastinal tumors: a comparison of adult and pediatric populations at a single Japanese institution. J Surg Oncol. 2003;83:24–30. 4 Teplick JG, Nedwick A, Haskin ME. Roentgenographic features of thymolipoma. Am J Roentgenol Radium Ther Nucl Med. 1973;117:873–7. 5 Roque C, Rodriguez P, Quintero C, Santana N, Hussein M, Freixinet J. Giant thymolipoma. Arch Bronconeumol. 2005; 41:402–3. 6 Moran CA, Rosado-de-Christenson M, Suster S. Thymolipoma: clinicopathologic review of 33 cases. Mod Pathol. 1995;8:741–4.
Paediatrics and International Child Health
2014
VOL .
34
NO .
3
231
Parakh et al.
Infantile thymolipoma
7 Tan TW, Kim DS, Wallach MT, Mangray S, Luks FI. Thoracoscopic resection of a giant thymolipoma in a 4-yearold girl. J Laparoendosc Adv Surg Tech A. 2008;18:903–5. 8 Gregory AK, Connery CP, Resta-Flarer F, Davis JE, Semel L, Holgersen LO. A case of massive thymolipoma. J Pediatr Surg. 1997;32:1780–2. 9 Kitano Y, Yokomori K, Ohkura M, Kataoka T, Narita M, Takemura T. Giant thymolipoma in a child. J Pediatr Surg. 1993;28:1622–5. 10 Dunn BH, Frkovick G. Lipomas of the thymus gland. Am J Pathol. 1956;32:41–51. 11 Abi Ghanem M, Habambo G, Bahous J, Chouairy C, Abu Khalil B. Large thymolipoma causing primarily respiratory distress. J Med Liban. 2012;60:106–9. 12 Retigen D, Fetter BF, Roses A, McCarty KS Jr. Thymolipoma in association with myasthenia gravis. Arch Pathol Lab Med. 1978;102:463–6. 13 Scully NM. Lipothymoma with cystic lymphangioma. Am Surg. 1960;26:400–4. 14 Benton C, Gerard P. Thymolipoma in a patient with Graves’ disease. J Thorac Cardiovasc Surg. 1966;51:428–32. 15 Mohan Rao PS, Moorthy N, Shankarappa RK, Bhat P, Nanjappa MC. Giant mediastinal thymolipoma simulating cardiomegaly. J Cardiol. 2009;54:326–9.
232
Paediatrics and International Child Health
2014
VOL .
34
NO .
16 Rosado-de-Christenson ML, Pugatch RD, Moran CA, Galobardes J. Thymolipoma: analysis of 27 cases. Radiology. 1994;193:121–6. 17 Hudacko R, Aviv H, Langenfeld J, Fyfe B. Thymolipoma: clues to pathogenesis revealed by cytogenetics. Ann Diagn Pathol. 2009;13:185–8. 18 Steger C, Steiner HJ, Moser K, Fiechtl H, Moser P, Schmid T, et al. A typical thymic carcinoid tumour within a thymolipoma: report of a case and review of combined tumours of the thymus. BMJ Case Rep. 2010; doi: 10.1136/bcr.04.2010.2958. 19 Haddad H, Joudeh A, El-Taani H, Mansour A, Morcos B, Fayoumi S, et al. Thymoma and thymic carcinoma arising in a thymolipoma: report of a unique case. Int J Surg Pathol. 2009;17:55–9. 20 Morini M, Bettini G, Diana A, Spadari A, Casadio Tozzi A, Santi M, et al. Thymofibrolipoma in two dogs. J Comp Pathol. 2009;141:74–7. 21 Sivaraman A, Jaikaran GK, Suresh RV, Sashank RK. Giant thymoliposarcoma presented like thymolipoma. Eur J Cardiothorac Surg. 2011;39:e146–7. 22 Ogino S, Franks TJ, Deubner H, Koss MN. Thymohemangiolipoma, a rare histologic variant of thymolipoma: a case report and review of the literature. Ann Diagn Pathol. 2000;4:236–9. 23 Gamanagatti S, Sharma R, Hatimota P, Guleria R, Arvind S. Giant thymolipoma. Am J Roentgenol. 2005;185:283–4.
3
Copyright of Paediatrics & International Child Health is the property of Maney Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
Giant thymolipoma in an infant Ankit Parakh1, Varinder Singh1, R. Subramaniam1, Mahender Kaur Narula2, Surendra Kumar Agarwala3, Shailaja Shukla4 Departments of 1Pediatrics, 2Radiology, 3Pediatric Surgery and 4Pathology, Lady Hardinge Medical College and Kalawati Saran Children’s Hospital, New Delhi, India Thymolipomas are benign neoplasms that usually occur in adults and are rarely described in children. They are usually detected incidentally but can be of massive size and lead to respiratory compromise. A 6month-old boy presented with respiratory distress and an anterior mediastinal mass which proved to be a thymolipoma. He underwent surgical resection and remains well on follow-up. Although rare, thymolipomas should be considered in the differential diagnosis even in infants presenting with an anterior mediastinum mass. Keywords: Anterior mediastinal mass, Infant, Thymolipoma
Introduction Thymolipoma is a rare benign anterior mediastinal tumor mainly limited to adults.1–6 It is usually asymptomatic, but can enlarge significantly prior to diagnosis and can cause significant symptoms.7–9 A 6month-old boy presented with respiratory distress which was found to be caused by a giant thoracic thymolipoma.
Case Report A 6-month-old boy presented to Kalawati Saran children’s hospital with rapid breathing for the previous 3 months. There was no associated fever, cough or difficulty in feeding. He was born at term, was developmentally normal and appropriately immunised for his age. On examination, the heart rate was 136/min, respiratory rate 66/min, and there were mild intercostal and subcostal retractions. He was otherwise alert and active. His weight was 6.4 kg (3rd centile), length 66 cms (25th centile), and his weight-for-length was ,3rd centile. Pulse oximetry showed a saturation of 95% in room air. There was no significant lymphadenopathy. Chest examination demonstrated tracheal shift to the right side and the cardiac apex was shifted to the right. Breath sounds were reduced on the left side with an impaired percussion note. Heart sounds were heard better over the right hemithorax. S1 and S2 heart sounds were normal with no murmurs. There were no features of superior vena cava obstruction. Abdomen examination was normal with no hepatosplenomegaly. The remainder of the examination was normal.
Investigations. Complete blood count, renal and liver function tests, uric acid and serum lactate dehydrogenase levels were within normal limits. A chest radiograph demonstrated a homogenous opacity involving the entire left hemithorax with collapse of the lower lobe of the left lung and a marked mediastinal shift (Fig. 1a). The right lung appeared normal. A contrast-enhanced CT of the thorax showed a large heterogeneous mass with fat tissue density occupying the entire left hemithorax with extensions into the anterior mediastinum and partially into the right hemithorax, along with mediastinal shift and atelectasis of the surrounding lung tissue (Fig. 1b). There was no infiltration into the pericardium, chest wall or diaphragm. An echocardiogram was normal. An ultrasound-guided tru-cut biopsy was undertaken in the left anterior axillary line in the third intercostal space. Histopathological examination of the biopsy specimen deonstrated an admixture of mature adipose tissue and normal thymic tissue with Hassal’s corpuscles consistent with thymolipoma (Fig. 1c). A left anterior thoracotomy demonstrated a large mass occupying the left thoracic cavity and the anterior mediastinum with no evidence of any pericardial, vascular or hilar invasion. When excised, itt weighed 840 g (Fig. 1d). Histopathology confirmed a large multifocal thymolipoma. The child made a rapid and uneventful recovery. He was discharged 1 week after surgery and remains well under follow-up for the last year.
Discussion Correspondence to: A Parakh, Department of Pediatrics, Lady Hardinge Medical College and Kalawati Saran Children’s Hospital, New Delhi – 110001, India. Email: [email protected]
230
ß W. S. Maney & Son Ltd 2014 DOI 10.1179/2046905513Y.0000000108
Thymolipoma is a rare, well encapsulated, benign anterior mediastinal tumour which was first reported
Paediatrics and International Child Health
2014
VOL.
34
NO.
3
Parakh et al.
Figure 1 (A): Chest radiograph demonstrating a homogeneous mass in the left hemithorax; (B) Contrast CT of thorax showing the anterior mediastinum with an extensive fat component (arrow); (C) Photomicrograph (H&E 610) showing an admixture of adipocytes (arrow) with thymus tissue (arrow head); inset demonstrating Hassal’s corpuscles (arrow); (D) Gross appearance showing a lobulated pink/ yellow mass weighing 840 g
by Lange in 1916.1 Lange described it as a lipoma of the thymus; however, the term ‘thymolipoma’ was used first by Hall in 1948.2 Overall, thymic neoplasms comprise only 4% of all mediastinal tumours in children,3 and only 2–9% of these are reported to be thymolipomas.4,5 The ages of patients range from 2 to 64 years (mean 33) with no gender predilection.6 A thorough search of the literature using PubMed found very few cases in the paediatric population6–9 and no case reported in infancy. The youngest case in the literature was 2 years old.6 Thymolipomas usually run an indolent, asymptomatic course, with most cases discovered incidentally as huge anterior mediastinal masses on chest roentgenogram. The tumour can enlarge, mould and accommodate in the thoracic cavity, often achieving massive dimensions before presentation. In most cases they weigh more than 500 g with 25% weighing more than 2000 g and the largest size reported in the literature being 6000 g.10 The mass can be very large, as in our case (840 g in a 6.4-kg infant 13% of bodyweight) and can lead to respiratory compromise or failure.11 In adults, thymolipoma is known to be associated with other diseases such as myasthenia gravis,12 cystic lymphangioma13 and Graves’ disease,14 although none of these were present in our case. On routine chest radiograph, the tumour may appear as a sharply circumscribed mediastinal density simulating cardiomegaly, pericardial effusion or a pericardial tumour.15 The CT and MRI appearance of thymolipoma is characteristic and is very helpful in diagnosing anterior mediastinum lesions, especially thymic masses. On thoracic CT, the tumour appears as linear strands and whorls of soft tissue intermixed
Infantile thymolipoma
with fat or as rounded islands of soft tissue surrounded by fat.16 On MRI, the adipose tissue within the tumour appears iso-intense in T1-weighted images whereas it remains suppressed in T2-weighted images, when the remainder of the thymic tissue is enhanced.16 The pathogenesis of thymolipoma is controversial. Replacement of diffuse thymic hyperplasia by adipose tissue seems to be the most widely accepted explanation.10 It has also been suggested that both thymic and fatty tissue are neoplastic and contribute equally to the development of the thymolipoma.2 Recent reports also suggest that thymolipoma is a neoplasm of thymic fat with translocation involving the HMGA2 gene on chromosome 12q15.17 Owing to the small number of cases in the literature, there are no clear recommendations on the best management of thymolipomas. In patients presenting with respiratory distress (as in this case), surgical resection of the tumour is required and is curative. Whether small lesions detected incidentally can be managed conservatively is still unclear. Spontaneous involution of the tumour has not been described. Although benign, thymolipomas have rarely been associated with malignancies such as thymic carcinoid tumours,18 thymomas and thymic carcinomas.19 Variants such as thymofibrolipomas,21 thymoliposarcomas21 and thymohaemangiolipoma22 have also been described. Hence, it is justified to consider a biopsy in all cases even with characteristic imaging. In view of its associations such as with myasthenia gravis, immune disorders, unusual variants and a small risk of malignancy, surgery should be considered in all cases. The above associations have been reported in adults only. The encapsulated nature of thymolipomas and lack of invasion into adjacent structures allows for relatively uncomplicated surgical excision of the tumour.23 Recurrences have not been reported. This case highlights the occurrence of a rare tumour which usually affects adults but can occur as early as in infancy.
References 1 Lange L. Uberein Lipom des Thymus [A lipoma of the thymus]. Zentralbl Allg Pathol. 1916;27:97–101. 2 Hall GFM. A case of thymolipoma with observations on a possible relationship to intrathoracic lipomata. Br J Surg. 1948;36:321–4. 3 Takeda S, Miyoshi S, Akashi A, Ohta M, Minami M, Okumura M, et al. Clinical spectrum of primary mediastinal tumors: a comparison of adult and pediatric populations at a single Japanese institution. J Surg Oncol. 2003;83:24–30. 4 Teplick JG, Nedwick A, Haskin ME. Roentgenographic features of thymolipoma. Am J Roentgenol Radium Ther Nucl Med. 1973;117:873–7. 5 Roque C, Rodriguez P, Quintero C, Santana N, Hussein M, Freixinet J. Giant thymolipoma. Arch Bronconeumol. 2005; 41:402–3. 6 Moran CA, Rosado-de-Christenson M, Suster S. Thymolipoma: clinicopathologic review of 33 cases. Mod Pathol. 1995;8:741–4.
Paediatrics and International Child Health
2014
VOL .
34
NO .
3
231
Parakh et al.
Infantile thymolipoma
7 Tan TW, Kim DS, Wallach MT, Mangray S, Luks FI. Thoracoscopic resection of a giant thymolipoma in a 4-yearold girl. J Laparoendosc Adv Surg Tech A. 2008;18:903–5. 8 Gregory AK, Connery CP, Resta-Flarer F, Davis JE, Semel L, Holgersen LO. A case of massive thymolipoma. J Pediatr Surg. 1997;32:1780–2. 9 Kitano Y, Yokomori K, Ohkura M, Kataoka T, Narita M, Takemura T. Giant thymolipoma in a child. J Pediatr Surg. 1993;28:1622–5. 10 Dunn BH, Frkovick G. Lipomas of the thymus gland. Am J Pathol. 1956;32:41–51. 11 Abi Ghanem M, Habambo G, Bahous J, Chouairy C, Abu Khalil B. Large thymolipoma causing primarily respiratory distress. J Med Liban. 2012;60:106–9. 12 Retigen D, Fetter BF, Roses A, McCarty KS Jr. Thymolipoma in association with myasthenia gravis. Arch Pathol Lab Med. 1978;102:463–6. 13 Scully NM. Lipothymoma with cystic lymphangioma. Am Surg. 1960;26:400–4. 14 Benton C, Gerard P. Thymolipoma in a patient with Graves’ disease. J Thorac Cardiovasc Surg. 1966;51:428–32. 15 Mohan Rao PS, Moorthy N, Shankarappa RK, Bhat P, Nanjappa MC. Giant mediastinal thymolipoma simulating cardiomegaly. J Cardiol. 2009;54:326–9.
232
Paediatrics and International Child Health
2014
VOL .
34
NO .
16 Rosado-de-Christenson ML, Pugatch RD, Moran CA, Galobardes J. Thymolipoma: analysis of 27 cases. Radiology. 1994;193:121–6. 17 Hudacko R, Aviv H, Langenfeld J, Fyfe B. Thymolipoma: clues to pathogenesis revealed by cytogenetics. Ann Diagn Pathol. 2009;13:185–8. 18 Steger C, Steiner HJ, Moser K, Fiechtl H, Moser P, Schmid T, et al. A typical thymic carcinoid tumour within a thymolipoma: report of a case and review of combined tumours of the thymus. BMJ Case Rep. 2010; doi: 10.1136/bcr.04.2010.2958. 19 Haddad H, Joudeh A, El-Taani H, Mansour A, Morcos B, Fayoumi S, et al. Thymoma and thymic carcinoma arising in a thymolipoma: report of a unique case. Int J Surg Pathol. 2009;17:55–9. 20 Morini M, Bettini G, Diana A, Spadari A, Casadio Tozzi A, Santi M, et al. Thymofibrolipoma in two dogs. J Comp Pathol. 2009;141:74–7. 21 Sivaraman A, Jaikaran GK, Suresh RV, Sashank RK. Giant thymoliposarcoma presented like thymolipoma. Eur J Cardiothorac Surg. 2011;39:e146–7. 22 Ogino S, Franks TJ, Deubner H, Koss MN. Thymohemangiolipoma, a rare histologic variant of thymolipoma: a case report and review of the literature. Ann Diagn Pathol. 2000;4:236–9. 23 Gamanagatti S, Sharma R, Hatimota P, Guleria R, Arvind S. Giant thymolipoma. Am J Roentgenol. 2005;185:283–4.
3
Copyright of Paediatrics & International Child Health is the property of Maney Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use.
