Giant thymolipoma in a 16-year-old girl with multimodal diagnostic approach and surgical management: a case report

Introduction

Thymolipomas are rare benign tumors, constituting approximately 2–9% of all thymic tumors (1,2). They typically originate in the anterior mediastinum and are comprised of adipose tissue and thymic elements. Despite their benign nature, thymolipomas can grow to considerable sizes, presenting diagnostic and therapeutic challenges, particularly in pediatric populations where they are less common. While these tumors are typically asymptomatic and discovered incidentally, their potential for growth and large size can cause symptoms of mass effect (3). Thymolipomas, due to their rarity and asymptomatic nature, often go undiagnosed until they reach a significant size, potentially impacting surrounding anatomical structures. In pediatric patients, the presentation of such tumors can be particularly alarming due to the limited thoracic space and the potential for rapid growth. Current literature provides limited guidance on the optimal diagnostic and management strategies for large thymolipomas in pediatric patients, underscoring a critical knowledge gap that this case aims to address. This case report aims to illustrate the effective use of a multimodal imaging approach in diagnosing a giant thymolipoma in a pediatric patient, detailing the surgical management and postoperative outcomes. By documenting this case, we hope to enhance understanding of the presentation and progression of thymolipomas in young patients and to highlight the importance of tailored diagnostic and therapeutic strategies in achieving optimal outcomes. We present this case in accordance with the CARE reporting checklist (available at https://acr.amegroups.com/article/view/10.21037/acr-24-157/rc).

Case presentation

A teenage girl presented to our clinic after an incidental finding on a routine chest radiograph during a school health check-up in January 2019. She had no previous medical history of note and reported no symptoms, specifically no breathlessness, cough, or weight loss, which are occasionally associated with mediastinal masses. Upon presentation, her physical examination was unremarkable, with no palpable masses or lymphadenopathy. Her vital signs were stable, and she appeared well-developed and well-nourished for her age. Given the findings on the chest radiograph, further diagnostic evaluation was pursued. A contrast-enhanced computed tomography (CT) scan of the thorax revealed a large, well-defined mass measuring approximately 15 cm × 10 cm × 20 cm in the anterior mediastinum extending into the right hemithorax (Figure 1). The mass was noted to compress the right lung and displace the mediastinal structures slightly to the left, without signs of invasion into adjacent tissues. Subsequent magnetic resonance imaging (MRI) of the chest confirmed the presence of a heterogeneously enhancing, predominantly fatty mass consistent with thymolipoma characteristics (Figure 2). Although both CT and MRI provided information on the tumor’s relationship with vascular structures, MRI offered superior soft tissue contrast and was particularly beneficial in confirming the tumor’s fatty composition. While CT and MRI provided comprehensive anatomical details, contrast-enhanced ultrasound (CEUS) contributed additional functional information by assessing the vascularity of the tumor. The CEUS pattern of uniform, slow, low enhancement fading away gradually suggested benign characteristics, complementing the anatomical findings (Figure 3). Moreover, CEUS played a key role in guiding the fine-needle aspiration biopsy, allowing for safe and accurate sampling of the tumor. Despite the diagnostic information provided by CT and MRI, a fine-needle aspiration biopsy was deemed necessary due to the large size and heterogeneous nature of the tumor. The biopsy provided cytological confirmation of the benign characteristics of the thymolipoma, thus ruling out any potential malignancy and reinforcing the surgical treatment plan. Cytological analysis identified adipose tissue and benign thymic elements, supporting the diagnosis of thymolipoma. Given the size of the tumor and its effects on surrounding structures, surgical intervention was recommended after multi-discipline treatment discussion.

Figure 1 Thoracic contrast-enhanced computed tomography scanning. High-density images in the lung window and low-density images in the soft tissue window showing a giant thymoma, tumor size approximately 15 cm × 10 cm × 20 cm.

Figure 2 Magnetic resonance imaging. The images show lumps with predominantly fat. The first image is a T2 weighted fat suppressed. The second image is a T1 weighted image without fat suppression.

Figure 3 Enhanced ultrasound. (A) In the arterial phase, the enhancement pattern showed uniform, slow. (B) In the venous phase, low enhancement then fading away slowly.

The patient underwent a median sternotomy, which allowed complete excision of the mass. Intraoperative findings confirmed that the tumor was well-capsulated and could be separated from surrounding tissues without significant complications. The excised tumor weighed approximately 2.9 kg (Figure 4A). Histopathological examination of the surgical specimen further confirmed the diagnosis of a benign thymolipoma, characterized by mature adipose tissue interspersed with normal thymic tissue (Figure 4B). No signs of malignancy or atypical features were observed.

Figure 4 Surgical specimens and longitudinal sections and postoperative pathologic findings on tissue. (A) The resected tumor weighed about 2.9 kg; the tumor was well-coated and separable from the surrounding tissue. (B) H&E stain of thymolipoma, original magnification ×40. The pathology is characterized by mature adipose tissue interspersed with normal thymic tissue. H&E, hematoxylin & eosin.

Postoperatively, the patient’s recovery was uneventful. She was discharged five days after surgery and followed up regularly. At her 1, 2-, 3-, 4-, and 5-year follow-up with MRI examination, she remained asymptomatic with no signs of recurrence on imaging studies, demonstrating an excellent surgical and postoperative outcome. The patient is very satisfied with the treatment process.

Timeline: During the 1st–9th days after hospitalization, laboratory examination and preoperative evaluation for detailed multidisciplinary evaluation and optimization of surgical planning. The 10th day was operation day. The 11th–22th days were postoperative duration (Figure 5).

Figure 5 Timeline of the case. CT, computed tomography; MRI, magnetic resonance imaging; CEUS, contrast enhanced ultrasound.

All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Helsinki Declaration (as revised in 2013). Written informed consent was obtained from the patients’ legal guardian for publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Discussion

This case illustrates the successful identification and management of a giant thymolipoma in a pediatric patient using a multimodal imaging approach. The key findings include the effective use of contrast-enhanced CT, MRI and ultrasound to not only diagnose thymolipoma but also accurately map its extent and relationships with surrounding structures, crucial for surgical planning (4-6). It is worth emphasizing that while CT and MRI were essential for mapping the anatomical extent of the tumor and its relationships with surrounding structures, CEUS complemented the anatomical details from CT and MRI by contributing dynamic, real-time functional data crucial for both diagnosis and surgical planning. The case underscores the importance of imaging in distinguishing thymolipomas from other mediastinal masses such as teratomas or more aggressive thymomas.

One of the strengths of this case was the use of a comprehensive diagnostic approach that integrated various imaging modalities, enhancing diagnostic accuracy and surgical outcome. The surgical strategy benefited significantly from the detailed anatomical information provided by MRI, which is less commonly used in the routine evaluation of thymolipomas but proved invaluable here. Specifically, MRI confirmed the fatty composition of the tumor, typical of thymolipomas, and provided a more detailed visualization of how the tumor displaced surrounding structures, including the vasculature. This level of detail allowed the surgical team to plan a safer and more precise resection by identifying and preserving critical blood vessels and minimizing the risk of intraoperative complications.

However, the case also highlights certain limitations. Although ultrasound-guided biopsy confirmed the diagnosis preoperatively, it carries inherent risks of sampling error, especially in large heterogeneous masses (1,3,7). Additionally, the rarity of pediatric thymolipomas may limit the generalizability of these findings (8).

Comparative literature suggests that while thymolipomas are often managed conservatively when asymptomatic, the decision for surgical intervention as in this case, is guided by symptoms, size, and potential for complications. In one set of studies, more than 50% patients may present with dyspnea, tachypnea, chest pain, upper respiratory tract infections, and rarely myasthenia gravis (9,10). A case has reported that pure red cell aplasia is an uncommon cause of anaemia rarely associated with thymolipoma (11). These patients were asymptomatic before detection. The literature corroborates our approach that complete surgical resection is curative and associated with excellent prognosis, echoing findings from larger cohorts (3).

The benign nature and slow growth pattern of thymolipomas make them suitable for complete surgical resection when indicated. This treatment is helpful in reducing symptoms caused by the compression of adjacent structures and autoimmune diseases (12,13). The absence of postoperative complications and recurrence in this case aligns with the benign characteristics of thymolipomas, where malignant transformation is exceedingly rare.

This case adds to the pediatric literature on thymolipomas, suggesting that a meticulous imaging and surgical approach can result in favorable outcomes even in cases involving large tumors (14,15). It calls for heightened awareness of this rare entity in differential diagnosis of anterior mediastinal masses in children and adolescents. Future research should aim to establish more defined guidelines or clinical diagnosis and treatment consensus for the management of large, asymptomatic thymolipomas in pediatric patients (16).

Conclusions

The successful management of a giant thymolipoma in this 16-year-old patient illustrates the critical role of multimodal imaging in diagnosing and planning treatment for this rare benign tumor. While complete surgical resection is often indicated for large or symptomatic thymolipomas, this case underscores the need for a tailored approach. This case highlights the importance of a balanced and individualized therapeutic strategy in pediatric oncology, with both proactive and conservative options depending on the clinical presentation.

Acknowledgments

Funding: This work was supported by grants from the International Cooperation Projects of the Science and Technology Department of Sichuan Province (Grant No. 2024YFHZ0322), the Sichuan Key Research and Development Project from the Science and Technology Department of Sichuan Province (Grant No. 2023YFS0044), and the Sichuan Province Clinical Key Specialty Construction Project ([2022]70).

Footnote

Reporting Checklist: The authors have completed the CARE reporting checklist. Available at https://acr.amegroups.com/article/view/10.21037/acr-24-157/rc

Peer Review File: Available at https://acr.amegroups.com/article/view/10.21037/acr-24-157/prf

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://acr.amegroups.com/article/view/10.21037/acr-24-157/coif). The authors have no conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee(s) and with the Helsinki Declaration (as revised in 2013). Written informed consent was obtained from the patients’ legal guardian for publication of this case report and accompanying images. A copy of the written consent is available for review by the editorial office of this journal.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Takeda S, Miyoshi S, Akashi A, 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. [Crossref] [PubMed]
2. Carapinha CP, Wainwright L, Loveland JA. A giant thymolipoma. SAJCH 2010;4:20.
3. Aghajanzadeh M, Alavi A, Pourrasouli Z, et al. Giant mediastinal thymolipoma in 35-year-old women. J Cardiovasc Thorac Res 2011;3:67-70. [PubMed]
4. Heimann A, Sneige N, Shirkhoda A, et al. Fine needle aspiration cytology of thymolipoma. A case report. Acta Cytol 1987;31:335-9. [PubMed]
5. Gupta R, Verma S, Bansal K, et al. Thymolipoma in child: a case diagnosed by correlation of ultrasound-guided fine needle aspiration (EUS-FNA) cytology and computed tomography with histological confirmation. Cytopathology 2014;25:278-9. [Crossref] [PubMed]
6. Halkos ME, Symbas JD, Symbas PN. Acute respiratory distress caused by massive thymolipoma. South Med J 2004;97:1123-5. [Crossref] [PubMed]
7. Aghajanzadeh M, Asgary MR, Mesbah A, et al. Giant thymolipoma of mediastinum and neck - initially misdiagnosed as liposarcoma by core needle biopsy. J Family Med Prim Care 2018;7:1079-82. [Crossref] [PubMed]
8. Joseph HT, Rathi RK, Goel H, et al. Symptomatic giant thymolipoma in a child. Lung India 2023;40:275-8. [Crossref] [PubMed]
9. Döngel I, İmamoğlu H, Şahin AF, et al. A Rare Mediastinal Tumor: Thymolipoma. Eur J Gen Med 2014;21-3.
10. Obeso Carillo GA, García Fontán EM, Cañizares Carretero MÁ. Giant thymolipoma: case report of an unusual mediastinal tumor. Arch Bronconeumol 2014;50:557-9. [Crossref] [PubMed]
11. Ferreira D, Ponraj R, Yeung A, et al. Pure Red Cell Aplasia Associated with Thymolipoma: Complete Anaemia Resolution following Thymectomy. Case Rep Hematol 2018;2018:8627145. [Crossref] [PubMed]
12. Savitt MA, Gao G, Furnary AP, et al. Application of robotic-assisted techniques to the surgical evaluation and treatment of the anterior mediastinum. Ann Thorac Surg 2005;79:450-5; discussion 455. [Crossref] [PubMed]
13. Ferrari G, Paci M, Sgarbi G. Thymolipoma of the anterior mediastinum: videothoracoscopic removal using a bilateral approach. Thorac Cardiovasc Surg 2006;54:435-7. [Crossref] [PubMed]
14. Soleimani H, Aminzadeh B, Hassannejad E, et al. A rare case of giant mediastinal thymolipoma in an 18-year man. Clin Case Rep 2024;12:e8530. [Crossref] [PubMed]
15. Benjamin SR, Miraclin T A, Mohammad A, et al. Giant mediastinal thymolipoma - complete resection through a sternotomy. Asian Cardiovasc Thorac Ann 2024;32:145-7. [Crossref] [PubMed]
16. Ufuk F, Ocak I. Enhancing Thymic Imaging: The Critical Need for Differentiating Thymolipoma from Liposarcoma in Clinical Practice. Radiographics 2024;44:e240112. [Crossref] [PubMed]