# What is the thymus gland and where is it located in the body? Canonical page: https://clinicsjo.com/en/faq/ma-hiya-al-ghudda-al-zaatariyah-wa-ayna-taqa-fi-al-jism Language: en Category: oncology Publisher: ClinicsJo Published: 2026-09-13T08:09:53.194Z Content updated: 2026-09-13T08:09:53.194Z Translation (ar): https://clinicsjo.com/ar/faq/ma-hiya-al-ghudda-al-zaatariyah-wa-ayna-taqa-fi-al-jism The thymus gland, also known as the thymus, is a small organ located in the upper chest, specifically behind the sternum and above the heart. This gland is an essential part of the lymphatic system, which plays a vital role in the body's immune function. Its primary function is to produce white blood cells, known as T-lymphocytes (T-cells), which help the body fight infections and other diseases [\[1\]](). The thymus grows gradually until puberty, after which it begins to shrink and is replaced by fatty tissue. However, in many adults with certain conditions such as myasthenia gravis, the thymus may remain enlarged. It is believed that the thymus may play a role in misdirecting immune cells, causing the immune system to attack its own healthy cells and tissues [\[3\]](). ## The Importance of the Thymus in the Immune System During childhood, the thymus plays a critical role in the development of the immune system. It is responsible for the production and differentiation of T-lymphocytes, a specialized type of white blood cell that protects the body against viruses and infections. These cells are essential for the adaptive immune response, as they learn to recognize and fight specific pathogens [\[3\]](). ## Tumors That May Form in the Thymus Different types of tumors can form in the thymus. The most notable are thymoma and thymic carcinoma, both of which are known as thymic epithelial tumors. These tumors arise from the cells covering the outer surface of the thymus [\[1\]](). - **Thymoma:** In this type, the cancer cells look very similar to normal thymus cells, grow slowly, and rarely spread outside the thymus [\[1\]](). - **Thymic Carcinoma:** In contrast, the cancer cells in this type do not look like normal thymus cells, grow more rapidly, and are more likely to spread to other parts of the body. Thymic carcinoma is considered more difficult to treat than thymoma [\[1\]](). These tumors are rare and are often discovered incidentally during a chest X-ray for other reasons [\[1\]](). You can learn more about this topic by visiting [Thymus Cancer: Symptoms, Diagnosis, and Treatment Options (Arabic)](). ## Conditions Associated with the Thymus The thymus is sometimes associated with autoimmune conditions, where the immune system attacks healthy body tissues. Myasthenia gravis is one of the most common autoimmune diseases associated with thymoma. In this condition, the immune system attacks the receptors that allow nerves to communicate with muscles, leading to muscle weakness [\[3\]](). Other conditions associated with thymoma include Good syndrome and pure red cell aplasia associated with thymoma [\[1\]](). ## When Should You See a Doctor? Because most patients do not show symptoms in the early stages of thymoma or thymic carcinoma, it is important to be aware of any unusual changes. If you suffer from a persistent cough, shortness of breath, chest pain, hoarseness, or swelling in the face, neck, upper body, or arms, you should consult a doctor. These symptoms may indicate a problem that requires medical evaluation [\[1\]](). In rare cases, if symptoms severely affect breathing, such as severe myasthenia gravis causing difficulty breathing, immediate emergency medical care may be required [\[3\]](). ## Medical references - [Thymoma and Thymic Carcinoma]() - [Myasthenia Gravis]() General health education; not a substitute for individualized clinical assessment. Citation URL: https://clinicsjo.com/en/faq/ma-hiya-al-ghudda-al-zaatariyah-wa-ayna-taqa-fi-al-jism#answer