Persistent hyperplasia of thymus

This code describes an abnormal and sustained overgrowth of the thymus gland, a primary lymphoid organ located in the chest. This hyperplasia is persistent, meaning it does not resolve spontaneously and may lead to symptoms due to compression of surrounding structures or immune system dysfunction.

Use this code when documentation explicitly states "persistent hyperplasia of thymus" or similar terminology indicating a chronic enlargement of the thymus gland. This diagnosis is often made following imaging studies (e.g., CT scan) and may be associated with conditions like myasthenia gravis, although this code specifically addresses the thymic pathology.

• Differentiate from transient thymic enlargement, which would not be coded as persistent hyperplasia.
• Consider sequencing this code as a secondary diagnosis if the thymic hyperplasia is a manifestation of another primary condition (e.g., myasthenia gravis).
• Ensure documentation specifies "persistent" to justify the use of this code over more general or acute thymic conditions.