What Are the Different Types of Thymus Cancer?

Thymic carcinoma is a rare mediastinal malignancy derived from thymic epithelial cells. The most common tissue types are squamous cell carcinoma and undifferentiated carcinoma. The histological behavior of thymoma is significantly different from the malignant biological behavior of thymoma. Thymic carcinoma is more common in adult men, with an average age of 50 years. Lymphoid epithelial carcinoma is also seen in children. Basal cell-like carcinoma is more common in middle-aged and older men. Mucoepidermoid and adenosquamous carcinoma are also found in middle-aged and elderly women.

Basic Information

Visiting department: Oncology, Thoracic Surgery
Multiple groups: Adult male

Common symptoms: Chest pain, chest discomfort
Contagious: no

Causes of thymic cancer

Thymic cancer is a tumor derived from cytological malignant thymic epithelium.

Clinical manifestations of thymic cancer

Most patients show chest pain or chest discomfort, and some patients may have symptoms such as weight loss, night sweats, cough, and dyspnea. If the tumor is large, the superior vena cava obstruction may appear. Most patients with thymic cancer have manifested invasion or metastasis when they were first discovered, and they usually invade peripheral organs or spread to the mediastinal lymph nodes, innominate veins, pleura, lungs, and pericardium. Individual patients may also show some subsymptoms of thymoma, such as with systemic lupus erythematosus. Very few patients with thymic cancer can be found only occasionally during physical examination without any clinical symptoms.

The clinical manifestations of thymic cancer are very similar to those of thymoma. In addition to the rapid metastatic symptoms of mediastinal metastases, they can also show extrathoracic metastases.

Thymic cancer test

X-ray and CT examinations of thymic cancer are non-specific, and the diagnosis is mainly based on pathological examination.

Immunohistochemical examination

It is the most important method to diagnose thymic cancer and distinguish thymic cancer from malignant thymoma, lung cancer and other malignant tumors. Most scholars have found through numerous studies that cytokeratin monoclonal antibodies are positive for almost all thymic cancers, and the application of different cytokeratin monoclonal antibodies is helpful for the diagnosis of thymic cancer subtypes.

2. EB virus antibody determination

EBV antibody testing is currently available for the diagnosis of thymic lymphoepithelial carcinoma. Patients with thymic lymphoepithelial carcinoma often have significantly higher antibody titers.

3. Chest X-ray

The most common manifestation is a solid mass. Most of the shadows are located in the anterior superior mediastinal thymus region. The masses vary in size, are irregular in shape, and dense in density, but they are uniform and dense. If the mass protrudes to one side of the thorax, it can overlap with the hilar and large vessel shadows. A few cases show sternal bone destruction.

4.CT inspection

It is of great value for judging the presence and extent of invasion of thymic cancer. Often manifested as a round or irregular mass in the anterior superior mediastinum, and can clearly show the extent of pleural or pericardial effusion. The enhanced CT film can clearly show the relationship between the mass and large blood vessels, which is of great reference value for the design of the surgical plan.

Thymic cancer diagnosis

Chest X-ray, CT, and percutaneous mediastinal tumor puncture are the main methods to diagnose the disease. The key to the diagnosis of thymic cancer is pathological examination. The diagnostic criterion is that tumor epithelial cells have obvious malignant cytological characteristics.

Differential diagnosis of thymic cancer

Anterior mediastinal metastatic adenocarcinoma

Because thymic cancer is very similar to nasopharyngeal, lung, kidney, genital, rectal anterior mediastinal adenocarcinoma. Unlike clear cells in the kidney and female genitourinary organ ducts, thymic clear cell carcinomas contain a large number of cytoplasmic tension filaments and well-formed cytoplasmic bodies, lack of microfilament formation and a large amount of glycogen. However, as long as the case is diagnosed with thymic cancer, detailed clinical data defining the primary extrathymic carcinoma must be considered.

2. Lymphoid epithelioma-like squamous cell carcinoma

Similarity to large cell lymphoma in the thymus region. Generally in thymic cancer, cytokeratin and EMA are positive and CLA negative.

3.Sperm cell tumor, embryo adenocarcinoma

Most are identified by histopathological examination, but occasional cases must use electron microscopy and immunocytochemical techniques. Testoma athymic carcinoma has cytoplasmic tension filaments and well-structured bridge bodies; on the other hand, testomas have a large amount of cytoplasmic glycogen and complex nucleoli. Embryo adenocarcinoma usually includes ultrastructured cytoplasmic AFP globules and lacks true tension filaments. Immunohistochemically, testomas were placental alkaline phosphatase positive, EMA negative, and cytokeratin negative. Embryonic adenocarcinoma is EMA negative, cytokeratin positive, and includes PLAP and AFP. Thymic carcinomas with thymic cysts may be indistinguishable from the pathology known as "proliferative thymic cysts," which are characterized by irregularities in the concave substratum of the cell nests within squamous cysts. However, unlike squamous adenocarcinoma, this type of hyperplasia is benign from a cellular perspective and has no spontaneous necrosis.

Thymus Cancer Treatment

Thymic cancer is a rare disease, standard treatment models have not been established, and there are few studies on the prognostic factors affecting survival. For cases where extensive or distant metastases have not occurred, surgical resection is the best option, and invasion of innominate veins is feasible for vascular reconstruction. Those who invade the pericardium and phrenic nerves are seeking resection together. For cases that are difficult to completely remove, palliative resection of the lesion can also reduce the tumor burden. Widely metastasis-prone lesions can be opened by thoracotomy or video-assisted thoracoscopy to clarify the pathological type. Chemotherapy. The effects of preoperative and postoperative radiotherapy on thymic cancer are unclear. Lymphocytic epithelioma is generally considered to be more sensitive to radiotherapy. The effect of postoperative adjuvant chemotherapy has not been determined.