edgepedia

Thymus

16 articles

Abscess of thymus

Abscess of thymus (suppuration of thymus), ICD-11 4B40.1 and ICD-10-CM E32.1, is a rare pus-forming infection of the thymus, seen in neonates, immunocompromised patients, or from adjacent infection, diagnosed by CT or MRI.

Cervical thymic cyst

Cervical thymic cyst is a rare, fluid-filled neck mass typically located near the carotid sheath. It is usually found incidentally and requires complete surgical excision for treatment.

Development of the thymus

Development of the thymus describes how the thymus arises from the third pharyngeal pouch, descends to the chest, is colonized by T cell precursors, and undergoes fat replacement after puberty.

Ectopic thymus

Ectopic thymus, also called ectopic cervical or intrathyroidal thymus, is thymic tissue stranded along the embryological descent path from the third pharyngeal pouch; a benign pediatric neck or thyroid finding that can mimic cancer.

Medullary thymic epithelial cell

Medullary thymic epithelial cell (mTEC): thymic medulla epithelial cell enforcing central tolerance via promiscuous gene expression of tissue-restricted antigens regulated by Aire and Fezf2; subsets mTEC I-IV include Aire+ mTEChi and tuft-like mTEC IV; AIRE mutations cause APS-1.

Stromal cell of thymus

Thymic stromal cells are the non-lymphocyte support cells of the thymus, including thymic epithelial cells, fibroblasts, endothelial cells, and pericytes, which build the microenvironment for T cell development, selection, tolerance, and age-related involution.

Thymectomy

Thymectomy is surgical removal of the thymus gland, performed in myasthenia gravis to improve weakness or remove a thymoma (about 10% of MG patients). The 2016 MGTX randomized trial confirmed benefit plus prednisone; MuSK-antibody MG is excluded.

Thymic cyst

Thymic cyst: fluid-filled sac within thymic tissue in the mediastinum or neck; congenital (unilocular) or acquired (multilocular, linked to inflammation or tumors). Benign, often asymptomatic; CT attenuation can mimic solid masses, MRI clarifies, surgery or surveillance.

Thymic hyperplasia

Thymic hyperplasia: benign enlargement or lymphoid follicular proliferation of the thymus, including true, rebound, follicular, and LESA-like types; linked to myasthenia gravis and Graves disease, distinguished from thymoma by chemical shift MRI.

Thymic involution

Thymic involution is the age-related atrophy of the thymus, replacing T-cell-producing epithelial tissue with fat from early life onward, reducing naive T cell output and raising infection, cancer, and autoimmune risk; partially reversible experimentally but no approved therapy.

Thymopentin

Thymopentin (TP-5), Arg-Lys-Asp-Val-Tyr, a synthetic pentapeptide matching amino acids 32-36 of thymopoietin; immunomodulator enhancing T-cell production, studied in HIV, tuberculosis, and eczema, never FDA-approved.

Thymosin

Thymosin: family of thymus-derived polypeptide hormones named in 1966 by Goldstein and White. Key members are thymosin alpha-1 (Zadaxin, sepsis and hepatitis studies, not FDA-approved) and thymosin beta-4 (actin-binding, wound healing, WADA-prohibited).

Thymulin

Thymulin, formerly known as FTS, is a zinc-dependent nonapeptide hormone produced by thymic epithelial cells that promotes T cell differentiation, discovered by French immunologists in the 1970s.

Thymus

Thymus: bilobed primary lymphoid organ in the superior mediastinum where T cells mature and undergo selection; undergoes involution from puberty; linked to myasthenia gravis, DiGeorge syndrome, and thymectomy.

Thymus histology

Thymus histology is the microscopic structure of the thymus, a two-lobed lymphoepithelial organ above the heart, organized into a thymocyte-packed cortex and a paler medulla containing Hassall's corpuscles.

Thymus transplantation

Thymus transplantation (cultured thymus tissue implantation, CTTI, RETHYMIC) treats congenital athymia by implanting cultured donor thymus slices into quadriceps muscle; FDA approved October 8, 2021, available at Duke and Great Ormond Street Hospital, 77% one-year survival.