Discussion of Thymic hyperplasia
- Two distinct histologic types of thymic hyperplasia:
- True thymic hyperplasia
- Lymphoid hyperplasia
- Both true thymic hyperplasia and lymphoid hyperplasia manifest as diffuse symmetric enlargement of the thymus, so that it is difficult to distinguish between the two types on the basis of imaging findings alone.
- It is important that radiologists be able to distinguish thymic hyperplasia from neoplasm.
- These two types are associated with different groups of pathologic conditions.
 Imaging Findings for Thymic hyperplasia
- Diffuse symmetric enlargement of the gland is the key morphologic feature of hyperplasia (neoplasm tends to manifest as a focal mass)
- FDG PET is often performed in patients with malignancy; however, differentiation between thymic hyperplasia and thymic involvement by malignancy is difficult because the thymus demonstrates normal physiologic uptake.
 See Also
 External Links
 References for Thymic hyperplasia
- Mizuki Nishino, Simon K. Ashiku, Olivier N. Kocher, Robert L. Thurer, Phillip M. Boiselle, and Hiroto Hatabu. The Thymus: A Comprehensive Review. RadioGraphics 2006 26: 335-348.