|Year : 2019 | Volume
| Issue : 6 | Page : 529-532
Cystic thymoma presenting as recurrent empyema
Lata Sampatrao Rajwad, Ketaki Vasudeo Utpat, Unnati Desai, Jyotsna Madanmohan Joshi
Department of Pulmonary Medicine, Topiwala National Medical and BYL Nair Charitable Hospital, Mumbai, Maharastra, India
|Date of Submission||18-Oct-2018|
|Date of Acceptance||27-Feb-2019|
|Date of Web Publication||17-Oct-2019|
Jyotsna Madanmohan Joshi
Department of Pulmonary Medicine, 2nd Floor, OPD Bldg., TNMC and BYL Nair Hospital, AL Nair Road, Mumbai - 400 008, Maharastra
Source of Support: None, Conflict of Interest: None
The lymphoma, thymoma and germ cell tumour are most common anterior mediastinal tumours. Thymoma account for 20% of mediastinal tumours and is the most common anterior mediastinal tumour. According to the 2015 WHO classification, the thymomas are classified according to 2 major features namely the shape of the epithelial cells and second is the amount of immature lymphocytes. Cystic thymoma is a rare variant of thymic neoplasm characterized by almost complete cystic degeneration with mixed internal structure. The clinical demeanour can range from an incidentally detected radiological finding to grave Para thymic syndromes. We herein describe a case of a 38 year-old male who presented with recurrent empyema. A contrast enhanced computed tomography of thorax done in the diagnostic workup unveiled a mediastinal cystic mass in right cardio phrenic angle. Mediastinal thymomas may rarely undergo cystic and necrotic changes and present as recurrent empyema's seen in our case.
Keywords: Cystic thymoma, empyema, mediastinal mass
|How to cite this article:|
Rajwad LS, Utpat KV, Desai U, Joshi JM. Cystic thymoma presenting as recurrent empyema. Med J DY Patil Vidyapeeth 2019;12:529-32
| Introduction|| |
Thymic neoplasms constitute <1% of all malignant neoplasms in adults. The most common epithelial thymic neoplasms are thymoma and thymic carcinoma. Thymoma occurs in adults after physiological thymic shrinkage and replacement by adipose tissue at the age interval of 40–60 years. Most thymomas are solid chest masses which are encapsulated and located in the anterior mediastinum. One-third of these lesions exhibit necrosis, hemorrhage, or cystic components, and one-third of cases show local-regional tumor spread, infiltrating the capsule and the surrounding anatomical structures. Cystic thymoma is a rare variant of thymic neoplasm, and although cystic regions are present in up to 40% of thymomas, those that are nearly entirely cystic are very rare. Approximately half of the patients harboring a thymic neoplasm are asymptomatic, while the remaining 50% may present with thoracic symptoms, such as dyspnea, chest pain, and a productive cough. Patients with thymoma are often affected with myasthenia gravis. Diagnostic imaging techniques are mandatory to assess patients with thymoma, and tomographic studies are requested to evaluate tumor spread into the mediastinum. The imaging studies include computed tomography (CT), magnetic resonance imaging, and positron emission tomography (PET). We discuss an intriguing presentation of a rare cystic thymoma.
| Case Report|| |
A 38 year old man was referred to our department for symptoms of cough with mucoid expectoration not associated with hemoptysis, right-sided chest pain, and exertional dyspnea of the Modified Medical Research Council Grade 1 for 5–6 years. He was a nonsmoker. History suggested an intake of empirical antituberculosis therapy thrice for right-sided large pleural effusion 20 years, 7 years, and 5 years ago. Diagnostic pleural fluid aspiration was done. However, in view of nonrelief, the patient had followed to our side. On general examination, the patient had Grade 1 clubbing. On respiratory system examination, movements were reduced along with signs of volume loss on the right side with breath sounds reduced in the right lower hemithorax. Routine hematological and biochemical laboratory investigations were within normal limits. Chest radiograph (CXR) [Figure 1] confirmed the right loculated pleural effusion with pleural thickening. The patient was evaluated further for the etiology. Diagnostic pleurocentesis was done. Pleural fluid routine microscopy revealed pus-like fluid which on analysis was exudates with degenerated neutrophils and normal adenosine deaminase level. The pleural fluid cartridge-based nucleic acid amplification test did not detect Mycobacterium tuberculosis. Pleural fluid was negative for parasitology. Electrocardiogram was within normal limits. A provisional diagnosis of right-sided empyema was made. The patient was managed with pigtail catheter insertion and antibiotics. After insertion of a pigtail, the patient was evaluated with a contrast-enhanced CT (CECT) of the thorax and 1200-ml fluid was aspirated [Figure 2] and [Figure 3], which showed a predominant cystic mass at the right cardiophrenic recess with calcific enhancing wall measuring 13.9 cm × 13 cm transverse dimensions and superoinferior extent with eccentric enhancing solid component measuring 5.1 cm × 2.8 cm along the posteromedial aspect of lower half. CT-guided biopsy of solid component was done. Histopathological examination was compatible with a diagnosis of thymoma, WHO Type AB, described as cores of the thymic tissue composed of lymphoid tissue intricately admixed with spindle-shaped cells [Figure 4]. The lymphoid cells showed mild variation in size and mitoses, a rich vascular network seen throughout the mass, with no necrosis and granuloma. Fluorodeoxyglucose PET-CT showed predominantly cystic mass lesion with peripheral low-grade metabolic activity and eccentric solid component involving the mediastinum and the right hemithorax. This was consistent with a known site of primary neoplasm with no distant metastases. The patient was referred for surgical excision. A right thoracotomy, decortication of the pleura, and excision of the mass were done.
|Figure 2: Contrast-enhanced computed tomography thorax showing a cystic mass in the right cardiophrenic recess|
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|Figure 3: Computed tomography thorax (coronal section) – cystic mass in the right cardiophrenic recess|
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| Discussion|| |
Thymoma is the most common primary anterior mediastinal tumor, with an overall incidence of 0.13 cases/100,000 person-years. Various tumors, including thymomas, may present with cystic degeneration developing mixed structure with solid and cystic components, and when degeneration is extensive, they might be almost entirely cystic. About 35%–40% of thymomas can undergo cystic degeneration. Cystic degeneration may vary from inconspicuous spaces that contain clear fluid to some larger cavities that contain blood or yellow-brown granular material. Occasionally, cystic changes result in a unilocular or multilocular cystic mass that has only a few recognizable small tumor nodules attached to its walls. They may be adherent to nearby structures and may simulate an invasive neoplasm at thoracotomy. Thymoma may rarely be associated with multilocular thymic cyst. Cystic thymoma can result in a gross pathologic appearance that simulates multilocular thymic cyst, but its histopathological examination shows a complete absence of epithelial lining within the cystic wall which is an important feature of cystic thymoma that differentiates it from thymic cyst. The WHO histological classification of thymoma, depending on the type of tumor cells, classifies thymoma as Type A containing oval- or spindle-shaped cells, Type B containing polygonal cells, and Type AB containing both types of cells. Type B tumors are subdivided into B1, B2, and B3 depending on the shape of tumor cell and extent of infiltration of lymphocytes. Thymic carcinoma is classified as Type C. The thymomas were also classified by the Masaoka staging system. Clinical stages were defined as Stage I – macroscopically encapsulated and microscopically no capsular invasion; Stage II – 1: macroscopic invasion into surrounding fatty tissue of mediastinal pleura or 2: microscopic invasion into capsule; Stage III – macroscopic invasion into neighboring organ; Stage IVa – pleural or pericardial dissemination; and Stage IVb – lymphogenous or hematogenous metastasis. The tumor affects men and women with equal propensity, and the 5th and 6th decades are the most commonly affected age groups. However, our patient was a young man in his fourth decade. The clinical presentation can be heterogeneous. A significant proportion of patients are asymptomatic and incidentally detected on a CXR done for some other purpose. Symptomatic patients can present with respiratory symptoms such as cough breathlessness or chest pain. A subset of patients may present with associated conditions such as myasthenia gravis or other systemic disorders, such as pure red cell aplasia, hypogammaglobulinemia, endocrine disorders, cutaneous disorders, and connective tissue disorders. These disorders coined as parathymic syndromes and are present in approximately 40% of patients with thymoma. Our patient had an offbeat presentation of a pleural involvement in form of empyema which persisted to be undiagnosed over several years and was treated with multiple courses of empirical antituberculous therapy before she visited us. However, this unusual presentation and recurrence of pleural effusion in our patient triggered suspicion and led us to evaluating for an alternative diagnosis or an associated condition. Hence, we proceeded with a CECT chest which uncovered a cystic mediastinal mass which was subsequently confirmed to be cystic thymoma. CT scan thus plays a crucial role in the detection as well as characterization of thymomas. The closest differential of a cystic mediastinal mass is an encysted pleural effusion. Encysted pleural effusions occur most commonly associated with conditions in which intense pleural inflammation emanates such as empyema, hemothorax, connective tissue disease malignancy, or tuberculosis. Sometimes, a focal intrafissural fluid collection may appear as a lung mass. This phenomenon is most commonly seen in patients with heart failure. Hence, it is pertinent to contemplate these differentials and to rule them out systematically. Meticulous history and timely imagine play pivotal roles.
Thymomas are located in the superior pericardium that is anterior to the aorta, pulmonary artery, or superior vena cava, although they have been described anywhere from the lower neck to the cardiophrenic border. The tumor is usually well defined, round or lobulated, homogeneous, which enhanced on contrast and sometimes heterogeneous or cystic, due to areas of hemorrhage and necrosis. It sheds light on the anatomic location of the lesion, its relationship to surrounding structures, and its tissue attenuation characteristics. CXR was deceptive in our case and was only suggestive of a loculated pleural collection. However, the unusual clinical picture triggered further evaluation in our case. Moreover, a CT scan helped us clinch the underlying mass lesion which on tissue assessment turned out to be a cystic thymoma. Based on Masaoka staging system, thymoma is treated by surgery, radiation therapy, and chemotherapy. All patients with resectable disease should undergo primary resection. The current treatment recommendations are as follows: (1) Stage I thymoma should be treated with surgery alone with microscopically complete resection; (2) Stage II and III thymoma should also be treated with surgical resection, and postoperative adjuvant radiation therapy is recommended for incompletely resected tumors; (3) Stage III and IVa thymoma should have surgery when possible and postoperative adjuvant radiation therapy is recommended, perioperative chemotherapy may be given to cases of incomplete resection; (4) Stage III and IVa thymoma which is not resectable is treated with multimodal therapy including chemotherapy, followed by surgery or radiation therapy; and (5) Stage IVb thymoma should be treated with chemotherapy. In adults, high response rates have been observed in cisplatin- and ifosfamide-based chemotherapeutic regimens. Standard chemotherapy regimens include cisplatin and etoposide (56%–60% response rate), cisplatin, adriamycin, and cyclophosphamide (51% response rate), adriamycin, cisplatin, vincristine, and cyclophosphamide (85%–92% response rate), and etoposide, ifosfamide, and cisplatin (32% response rate). As per the Masaoka staging, our patient was in the Stage of IVa without any other systemic manifestations; however, pleural dissemination was present. Hence, he was managed with a surgical resection.
| Conclusion|| |
Cystic thymoma may have uncommon clinical exhibitions as in our case. Furthermore, recurrent pleural effusions or empyema could have eclipsed etiologies such as mediastinal masses. Hence, a high index of suspicion for alternative diagnosis should be maintained in such unconventional circumstances.
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Conflicts of interest
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