"Cough and Fatigue Last for Months"... What Is This Little-Known Disease? [Health Talk]

[Financial News] If a cough lingers for a long time and unexplained fatigue continues, most people suspect a cold or bronchitis. But if symptoms persist for months or an abnormality is found in a health screening, it may be worth considering a rare disease called sarcoidosis.
Sarcoidosis is a systemic inflammatory disease that most often affects the lungs, but it can also cause inflammation in the skin, eyes, lymph nodes, heart, liver, and other organs. Experts say a proper understanding of the disease is needed, as it is often discovered incidentally on screening images without any clear symptoms.
Sarcoidosis was previously called "yuhyukjongjeung" in Korean. Its English name comes from the Greek word sarx, meaning "flesh," and eidos, meaning "like." The Korean term yuhyukjongjeung, written with Chinese characters, means a disease that takes on a form similar to sarcoma.
Moon Sung-woo, a pulmonology and allergy professor at Konkuk University Medical Center, explained, "The former name, yuhyukjongjeung, sounded like a malignant tumor, so many patients who were first diagnosed fell into fear and despair." He added, "But it is simply an inflammatory disease in which inflammatory cells cluster in the body. It is completely different from cancer, and in many patients it improves naturally without special treatment." To reduce unnecessary fear, the English name Sarcoidosis is now used as the official disease name. It is also listed in the NHIS disease classification and the national rare disease registry as sarcoidosis, including pulmonary sarcoidosis and lymph node sarcoidosis, under disease code D86.
Sarcoidosis is a disease in which the immune system, which should act as the body's defense barrier, overreacts for reasons that are not yet understood and forms tiny inflammatory clusters called noncaseating granulomas throughout the body. No clear single cause has been identified so far, but experts believe that an abnormal immune response may be triggered when people with a genetic predisposition are exposed to viruses, bacteria, or certain environmental substances. A nationwide study found that the average age at diagnosis in Korea is in the late 40s, the incidence rate is highest in people in their 50s, and the prevalence rate is highest in those in their 60s. Female patients were slightly more numerous than male patients. The disease is not known to be contagious between people.
The organs most commonly affected by granulomas are the lungs and the lymph nodes inside the chest, which are involved in more than 90% of patients. However, involvement does not necessarily mean symptoms. About 30% to 60% of patients with lung involvement live without obvious symptoms and are referred to a hospital after an abnormality is found incidentally on a chest X-ray during a health screening. When symptoms do appear, a dry cough, chest pain, and mild shortness of breath are common at first. As the disease progresses, it can affect the skin or eyes. In rare cases, when the heart or nervous system is involved, palpitations, dizziness, or weakness in the arms and legs may occur, so caution is needed.
Moon said, "Sarcoidosis appears in so many different ways that it is difficult to diagnose based on a single symptom." He added, "If a cough lasts for a long time or unexplained inflammation keeps recurring in multiple organs, it is best to seek specialist care."
Diagnosis begins with chest X-rays and CT scans to check for abnormally enlarged lymph nodes and lung nodules. A biopsy through bronchoscopy, or tissue sampling from the skin or lymph nodes, can help confirm noncaseating granulomas and support the diagnosis. It is important to distinguish sarcoidosis from diseases with similar imaging findings, such as tuberculosis, lymphoma, and fungal infections. If needed, lung function tests, blood tests, heart tests, and eye exams are performed to comprehensively assess the affected organs and the extent of the disease.
Moon explained, "The process of distinguishing sarcoidosis from other diseases is more important than anything else." He added, "Only by combining imaging tests, biopsy results, and clinical findings can doctors make an accurate diagnosis and determine the right treatment plan."


Treatment varies depending on the patient's condition. If symptoms are mild or there is no organ damage, regular follow-up alone may be enough. But if lung function declines or major organs such as the heart, eyes, or nervous system are affected, steroid treatment becomes the standard approach. Immunosuppressants may also be used when necessary, and biologic agents are now being applied in some patients. The length of treatment depends on the patient's symptoms and the degree of organ involvement, and long-term management may be required. Sarcoidosis is designated as a nationally managed rare disease, so patients who meet the diagnostic criteria can reduce medical costs by registering for the NHIS's catastrophic expense coverage program.
Although the label of a rare and incurable disease can feel heavy, experts say many patients improve naturally or remain stable with regular follow-up alone. However, some cases progress chronically and lead to pulmonary fibrosis. In rare cases involving the heart, the disease can have a major impact on prognosis, making ongoing monitoring, including regular electrocardiograms, necessary. It is also important to stay in close communication with medical staff, avoid smoking completely, and maintain overall physical strength through a balanced diet and proper exercise.
Moon emphasized, "Not every case of sarcoidosis follows a severe course." He added, "With regular medical care and consistent follow-up, most patients can maintain their daily lives, so rather than worrying too much, it is important to focus on an accurate diagnosis and timely treatment." 


[email protected] Reporter Jeong Myeong-jin Reporter