What is the difference between a thymoma and thymic carcinoma?

Thymoma and thymic carcinoma are two types of epithelial tumors that arise in the thymus, a small organ located in the upper chest behind the breastbone. Although they originate from the same cell type, they differ in their behavior, appearance under a microscope, and ability to spread.

Collectively, these tumors are known as thymic epithelial tumors (TETs) [1]. Thymoma is the more common of the two, while thymic carcinomas account for about one in five of these tumors. These tumors are often discovered incidentally during chest X-rays performed for other reasons [1].

Thymoma

In thymoma, the cancer cells look very similar to normal cells of the thymus. This type of tumor tends to grow slowly and rarely spreads outside the thymus [1]. However, thymoma can be associated with autoimmune conditions, such as myasthenia gravis, a chronic neuromuscular disease that causes weakness in voluntary muscles [3]. Other conditions associated with thymoma can include thymoma-associated hypogammaglobulinemia (Good syndrome) and pure red cell aplasia [1].

Thymic Carcinoma

In contrast, the cancer cells in thymic carcinoma do not look like normal thymus cells. This type of cancer grows faster and is more likely to spread to other parts of the body [1]. Thymic carcinoma is considered more difficult to treat than thymoma, and it has often already spread to other parts of the body by the time of diagnosis [1].

Diagnosis and Treatment

To diagnose thymoma and thymic carcinoma, doctors may order a range of tests such as a physical exam and medical history, chest X-rays, computed tomography (CT) scans, magnetic resonance imaging (MRI), and positron emission tomography (PET) scans. A biopsy is necessary to confirm the diagnosis, during which a tissue sample is removed and examined under a microscope [1].

Treatment options depend on the type and stage of the tumor and may include surgery to remove the tumor, radiation therapy, chemotherapy, hormone therapy, and targeted therapy. In some cases, chemotherapy may be used before surgery or radiation to shrink the tumor [1]. Because thymoma can recur long after treatment, and there is an increased risk of developing other types of cancer, lifelong follow-up is necessary [1]. For more detailed information on symptoms, diagnosis, and treatment, you can visit our page on Thymic Cancer: Symptoms, Diagnosis, and Treatment Options (Arabic).

The Importance of Distinguishing Between Them

Distinguishing between thymoma and thymic carcinoma is crucial because it directly affects the treatment plan and prognosis. Thymoma, being less aggressive, often responds well to surgery, which may be followed by radiation therapy [1]. Thymic carcinoma, due to its aggressive nature and tendency to spread, often requires a more comprehensive treatment approach that may include chemotherapy and targeted therapy in addition to surgery and radiation [1].

Medical references

• Thymoma and Thymic Carcinoma
• Myasthenia Gravis