Giant thymolipoma of mediastinum and neck - initially misdiagnosed as liposarcoma by core needle biopsy

Surgical resection of a giant thymolipoma causing respiratory failure: A case report

BACKGROUND

Thymolipoma is a rare benign tumor arising from the anterior mediastinal thymus and is composed of mature fatty tissue and interspersed nonneoplastic thymic tissue. This tumor accounts for only a small percentage of mediastinal masses, and the majority of them are asymptomatic and found incidentally. To date, fewer than 200 cases have been published in the world literature, of which most excised tumors weighed less than 0.5 kg and the largest weighed 6 kg.

CASE SUMMARY

A 23-year-old man presented with a complaint of progressive breathlessness for 6 mo. His forced vital capacity was only 23.6% of the predicted capacity, and his arterial partial pressure of oxygen and carbon dioxide were 51 and 60 mmHg, respectively, without oxygen inhalation. Chest computed tomography revealed a large fat-containing mass in the anterior mediastinum that measured 26 cm × 20 cm × 30 cm in size and occupied most of the thoracic cavity. Percutaneous mass biopsy revealed only thymic tissue without signs of malignancy. A right posterolateral thoracotomy was successfully performed to remove the tumor along with the capsule, and the excised tumor weighed 7.5 kg, which to our knowledge, was the largest surgically removed tumor of thymic origin. Postoperatively, the patient’s shortness of breath was resolved, and the histopathological diagnosis was thymolipoma. No signs of recurrence were observed at the 6-mo follow-up.

CONCLUSION

Giant thymolipoma causing respiratory failure is rare and dangerous. Despite the high risks, surgical resection is feasible and effective.

Cases

Thymolipoma is a rare benign anterior mediastinal tumour of thymic origin containing both thymic and mature adipose tissues. In most cases it has a silent course and can grow to large sizes before presenting with respiratory symptoms. We report a case of a giant thymolipoma in a 4-year-old girl treated at Chris Hani Baragwanath Academic Hospital, South Africa.

Trends, Symptoms, and Outcomes of Resectable Giant Mediastinal Tumors

Describing the changes in surgical procedures and factors affecting the surgical outcome of patients who have undergone complete resection of giant mediastinal tumors (GMTs, diameter ≥ 10 centimeters) could improve preoperative decision-making and prognostic evaluations. We accessed data from three sources, which are case reports on surgical treatment of GMTs from PubMed, Web of Science, and EMBASE until June 1, 2019; patients with resected GMT from the Surveillance, Epidemiology, and End Results (SEER) database; and retrospective review of medical records in our institution from 2000 to 2019. The worldwide distribution, clinicopathological characteristics, symptom profile, prognosis of patients with GMT resection, and nomogram for surgical outcome prediction are reported. A total of 242 rare GMT cases from four continents (Asia, North America, South America, and Europe) were included. The median age of the patients was 40 (IQR: 27, range: 13–83) years, and the male-to-female ratio was 1.57:1. Dyspnea, shortness of breath, cough, and chest pain or discomfort were the major symptoms at presentation. The prognosis of benign and low-grade malignant GMTs was superior to that of high-grade malignant GMTs. Tumor malignancy played the most critical role in predicting postoperative survival, followed by longest tumor diameter and a posterior mediastinum location. The findings of this study suggest that the number of successful GMT surgeries has increased over the last decade and describe clinical features of GMTs. Physicians should prioritize tumor malignancy as a leading factor in predicting outcome rather than tumor size.

Thymolipoma - the frontier between hamartoma and neoplasia?

Thymolipoma is an uncommon benign thymus lesion, with a partially deciphered etiopathogeny, being most frequently diagnosed in young patients, regardless of gender. Incidentally diagnosed in asymptomatic patients, larger thymolipomas lead to symptoms related to neighboring mediastinal structures compression, with an intensity which is correlated with the mass size. Our review presents the main epidemiological, pathogenic, clinicopathological and morphological characteristics of this rare pathology. Sometimes, thymolipomas may be associated with paraneoplastic syndromes, which are alleviated by the mass complete surgical resection. Imagistics may orientate the diagnosis, which is certified by the microscopic examination of the resection specimens. Extensive thymectomy remains the current therapeutic option and new tools have been developed to increase the accuracy of the surgical procedure to avoid incidental lesions of the important elements of the anterior mediastinum. Although rare, thymolipomas should be considered in the differential diagnosis of mediastinal masses and of paraneoplastic syndromes.