Extended abstract: clinical diagnosis and workup of prevascular mediastinal tumors

The most frequent prevascular mediastinal masses are thymic tumors, lymphomas, teratomas, and intrathoracic thyroid. Most of the prevascular mediastinal masses are incidental findings. Due to the location, it is difficult to obtain a tissue diagnosis and clinical diagnosis is crucial before deciding the best treatment options.

Thymic tumors are rare, the incidence is 0.13–0.32/100,000/year and they represent 0.2–1.5% of all malignancies. The incidence reaches the peak at the age of 30s and 70s with similar distribution between male and female (1).

It is always important to evaluate the clinical presentation in patients with mediastinal mass. Thirty percent to 50% of patients are asymptomatic. Cough, chest pain, fever/chills and dyspnea are the most frequent symptoms at diagnosis. Lymphoma clinical signs such as fever or night sweats (B symptoms) have to be investigated and excluded. In case of large mediastinal mass direct tumor invasion or compression of airways, vascular structures or nerves can cause respiratory compromise, diaphragmatic elevation, vocal cords paralysis with hoarseness, Horner syndrome, superior vena cava syndrome and dysphagia (2).

In a series of 47 patients with thymic epithelial tumors, 42.5% of patients with thymoma were asymptomatic (n=17), 19.1% presented with chest pain (n=7), and 40% presented with autoimmune manifestations mainly myasthenia gravis (MG) (n=11). In thymic carcinoma patients, only 14% were asymptomatic and there were no case of MG (3).

The release of excess hormones, antibodies, or cytokines releases are responsible for systemic symptoms. Associations with MG, Graves’ disease, and hematological disorders have been reported in the literature. Thirty percent to 50% of patients with thymoma present MG, but only 10–15% MG patients are diagnosed with thymoma. Pure red cell aplasia is rare, only 2% to 5%, and it is more common in women. Also, hypogammaglobulinemia has been reported in 2% to 5% of patients with thymic tumors (1,2).

The typical presentation of MG includes exertional voluntary muscle weakness and fatigability. In 15% of patients, ocular symptoms could represent the only symptoms (4). Typically, patients complain of diplopia and ptosis. In more severe forms of MG, patients may present with slurred speech, arms and legs weakness, difficulty chewing or swallowing with progression to generalize weakness and to respiratory insufficiency. In these patients, clinical examination and neurological evaluation are important to make a correct diagnosis.

Antibodies against the acetylcholine receptor, abnormal results of electrolytes, renal, and liver function tests can be associated with thymoma. As part of the differential diagnosis serum parathyroid hormone (PTH), α-fetoprotein, and β-human chorionic gonadotropin (β-hCG) levels have to be checked. If the germ cell tumor markers are elevated, malignant, non-seminomatous germ cell tumor should be considered as main diagnosis. Chemotherapy should be considered in malignant germ cell tumors and radical surgery for teratoma. The markers provide crucial information for diagnosis, prognosis, and response to treatment. A tissue biopsy is recommended considering the different treatment options available, usually in non-operable patients. The exact diagnosis has crucial clinical implications for selecting the most appropriate chemotherapy regimens.

As part of the preoperative work up lung function test and echocardiogram are mandatory tests to optimize the perioperative management. The clinical staging is usually completed with a chest computed tomography (CT) scan, and a positron emission tomography (PET) scan. A transesophageal echocardiogram and cardiac magnetic resonance imaging (MRI) are considered when there is concern regarding possible cardiac involvement in order to establish resectability. The MRI can also be used to better characterized the content of the mediastinal lesion and exclude a possible benign cyst.

In conclusion, clinical presentation with radiological imaging is crucial when no tissue biopsy is feasible to make a diagnosis. The radiological findings play a pivotal role but clinical symptoms and signs are equally important. The blood tests have to be considered to make differential diagnosis with teratoma, thyroid mass, and lymphoma when biopsy is not available.

Acknowledgments

Funding: None.

Footnote

Provenance and Peer Review: This article was commissioned by the Guest Editors (Malgorzata Szolkowska, Chul Kim, Mohammad Ashraghi, and Claudio Silva) for “The Series Dedicated to the 13th International Thymic Malignancy Interest Group Annual Meeting (ITMIG 2023)” published in Mediastinum. The article has undergone external peer review.

Peer Review File: Available at https://med.amegroups.com/article/view/10.21037/med-24-1/prf

Conflicts of Interest: The author has completed the ICMJE uniform disclosure form (available at https://med.amegroups.com/article/view/10.21037/med-24-1/coif). “The Series Dedicated to the 13th International Thymic Malignancy Interest Group Annual Meeting (ITMIG 2023)” was commissioned by the editorial office without any funding or sponsorship. The author has no other conflicts of interest to declare.

Ethical Statement: The author is 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.

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References

1. Rich AL. Epidemiology of thymoma. J Thorac Dis 2020;12:7531-5. [Crossref] [PubMed]
2. Sperling B, Marschall J, Kennedy R, et al. Thymoma: a review of the clinical and pathological findings in 65 cases. Can J Surg 2003;46:37-42. [PubMed]
3. Altshuler E, Mathavan A, Mathavan A, et al. Clinical characteristics, prognostic factors, and long-term outcomes associated with epithelial malignancies of the thymus: A 20-year single-institution experience. Cancer Rep (Hoboken) 2023;6:e1750. [Crossref] [PubMed]
4. Behbehani R. Ocular Myasthenia Gravis: A Current Overview. Eye Brain 2023;15:1-13. [Crossref] [PubMed]