Stages of Pulmonary Sarcoidosis — What Do They Really Mean?
In sarcoidosis, stages describe the location of granulomas—in the lungs, lymph nodes or both—and the nature of the disease. Staging is simply a way for doctors to categorise patients with sarcoidosis and should not be considered an indicator of severity.
Stage one indicates granulomas in the lymph nodes.
Stage two indicates lymph-node involvement together with granulomas in the lungs. At first this may appear to be a progressive diagnosis compared with stage one.
However, stage three indicates granulomas in the lungs but not in the lymph nodes. This shows that the stages are not a progression. A patient may move between stages—for example, someone may have stage two and later, with treatment or time, move to stage one or three, or enter complete remission.
Stage four is somewhat different from the other three. It indicates scarring in the lungs—pulmonary fibrosis—which is irreversible. For this reason, stage four is the most severe manifestation of sarcoidosis. This also contributes to the misconception that sarcoidosis stages necessarily progress.
A sarcoidosis stage does not indicate severity. Each stage can have a different level of severity. A person may have granulomas in the lungs but nowhere else (stage three) and be completely asymptomatic. Conversely, someone may have granulomas only in the lymph nodes (stage one) but experience severe pain, swelling or other complications.
All stages of pulmonary sarcoidosis can be serious. Any stage can cause significant symptoms and debilitating fatigue.
Source: https://www.stopsarcoidosis.org/stages-of-sarcoidosis/