DISCUSSION
Thymoma, a rare malignancy, accounts for 20%-25% of mediastinal tumors and exhibits a diverse range of clinical manifestations and an elusive etiology.4,5 The initial presentation of our patient was characterized by recurrent chest pain over five months, followed by a more subacute presentation with exertional dyspnea and decline in functional status. Although many cases of thymoma are asymptomatic, the indolent course, and pericardial involvement observed in this case is atypical and highlights the need for a high index of suspicion in patients presenting with persistent or recurrent symptoms.1 Riedel et al. previously reported several cases of indolent thymoma, corroborating our observation that thymoma can exhibit a largely indolent growth pattern.6
In this case, the decision to opt for a high-complexity fluoroscopy-guided pericardiocentesis was influenced by several key factors, each carrying significant implications for clinical practice. The patient’s initial presentation included a series of concerning symptoms, most notably exertional dyspnea and a significant decline in functional status, necessitating immediate symptomatic relief. In addition, the CT scan revealed an anterior mediastinal mass accompanied by a moderate to large pericardial effusion, yet without any indicators of significant obstruction or tamponade physiology, thereby allowing for a planned, rather than urgent, approach. Thus, fluoroscopy-guided pericardiocentesis, being a minimally invasive procedure, was the modality of choice serving a dual purpose: it facilitated symptom relief by enabling the removal of pericardial effusion and concurrently allowed for the examination of the fluid for malignant cells.7,8 However, prior studies have showed that cancer cells can migrate to the pericardial fluid and performing pericardiocentesis might pose risk for dissemination.9,10 Therefore, there existed substantial concerns regarding malignancy and the potential risk of tumor dissemination. In fluoroscopy-guided pericardiocentesis, the utilization of fluoroscopy ensured precision in needle placement, minimizing the risk of complications such as cardiac tamponade or puncture of surrounding structure, in addition to reducing the risk of malignant cells migration.
The histological classification of thymomas predominantly relies on tumor cytomorphology. However, the World Health Organization (WHO) classification has undergone several modifications over time, leading to a more nuanced understanding of specific tumor types.11 In this patient, the core biopsy tissue analysis confirmed a thymoma, subtype WHO B2, characterized by a mixture of small round lymphocytes and epithelial cells with ill-defined cell borders, separated by broad fibrous bands and highlighted by immunohistochemical staining for CK5 and p40. The absence of necrosis or cytologic features of carcinoma suggested a lower risk of aggressive behavior. The chosen subtype (WHO B2), while being more aggressive than B1 subtype, is not linked with high invasiveness or aggressive migration, reaffirming the suitability of the chosen approach.11 However, the literature scarcely addresses the indolent course of the B2 subtype, making this case potentially indicative of broader implications that warrant further exploration and research.12
Within the expansive arsenal for managing thymoma, surgical resection is a cornerstone, especially for localized entities. The indolent nature and subacute presentation of our case allowed for a non-urgent, thoughtful approach to intervention. This aligns with the case reported by Azuma et al., where a giant tumor necessitated immediate surgical intervention.13 In Azuma’s case, the patient showed various clinical symptoms and was also diagnosed with WHO B2 thymoma. Despite being the same subtype, our patient’s gross pathology of the tumor showed a more aggressive and expansive pattern, which further testified to the surgical approach. In addition, our patient showed a concurrent pericardial effusion, which necessitated an in-depth exploration. However, it’s worth noting that B2 subtype thymoma has a high recurrence rate at 18.6% for the particular subtype and up to 50% for Masaoka stage.14 This implies necessity for vigilant postoperative surveillance and comprehensive long-term management plan.
Comparing this case with similar instances documented in the literature highlights some distinct characteristics. For example, Bakhriansyah J. et al. detailed a case of a patient with advanced thymoma complicated by purulent pericarditis.15 Similar to our approach, Bakhriansyah J. et al. also chose fluoroscopy-guided pericardiocentesis, reinforcing the safety and effectiveness of this method. However, our case manifested a more indolent course and a semi-emergent situation, contrasting with the more acute presentation in the case reported by Bakhriansyah J. et al. This difference underscores the variability in the clinical presentation of thymomas and highlights the necessity for individualized, case-by-case decision-making in managing these patients. Khan et al. reported a case with cardiac tamponade, which they chose to open an emergent pericardial window for pericardial drainage.16 This difference in approach between the case reported by Khan et al. and our own highlights the importance of considering the overall health status of the patient and the specific characteristics of the tumor when selecting an appropriate treatment strategy. In the case reported by Khan et al., the presence of cardiac tamponade, a life-threatening emergency, necessitated immediate intervention to drain the pericardial effusion, thereby justifying the choice for an emergent pericardial window. In contrast, our patient presented with a more subacute course, without signs of significant obstruction or tamponade physiology, allowing us to opt for a less invasive, yet equally effective, fluoroscopy-guided pericardiocentesis. This not only provided immediate symptomatic relief but also enabled us to obtain a sample for cytological examination, thereby aiding in the diagnosis and subsequent treatment planning.