Search
thymoma
Most common tumor in the anterior mediastinum.
Also see thymic carcinoma.
Pathology:
- ~30-40% are invasive.
- may be cystic.
Microscopic pathology:
WHO classification [3]
- type A (spindle cell; medullary)
- type AB (mixed)
- type B1 (lymphocyte rich; lymphocytic; predominantly cortical; organoid)
- type B2 (cortical)
- type B3 (epithelial; atypical; squamoid; well differentiated thymic carcinoma)
- micronodular thymoma
- metaplastic thymoma
- microscopic thymoma
- sclerosing thymoma
- lipofibroadenoma
microscopic subtyping does not correlate with clinical behavior:
1) lymphocyte predominant
2) mixed lymphoepithelial
3) epithelial cell predominant
4) spindle cell (variant of epithelial tumors)
correlates with degree of local invasion & appears to correlate with prognosis:
1) cortical
2) medullary (better prognosis)
3) mixed
Clinical manifestations: (associations)
1) myasthenia gravis (~30-40% incidence in thymoma)
2) red cell aplasia
3) hypogammaglobulinemia (IgA, IgG & IgM decreased)
4) mucocutaneous candidiasis
5) Cushing's syndrome (ACTH from thymic carcinoid)
Staging:
- Stage I. totally encapsulated
- Stage IIA. totally resected, microscopic invasion of capsule
- Stage IIB. transcapsular invasion of mediastinal soft tissue or pleura
- Stage III. invade pericardium, great vessels or lungs
- Stage IVA. seed pericardium or pleura
- Stage IVB. distant metastases
~30-40% of thymomas are invasive.
Radiology:
- computed tomography (CT) of thorax (mediastinum)
Complications:
1) bacterial infections
2) viral infections
a) Herpes simplex
b) cytomegalovirus
Management:
1) surgery: thymectomy
2) intravenous immunoglobulin for hypogammaglobulinemia
- thymectomy does not improve hypogammaglobulinemia
Related
mediastinal neoplasm
thymic carcinoma
thymus
General
embryonal neoplasm
thymic neoplasm
References
- Mayo Internal Medicine Board Review, 1998-99, Prakash UBS (ed)
Lippincott-Raven, Philadelphia, 1998, pg 774
- Medical Knowledge Self Assessment Program (MKSAP) 11, American
College of Physicians, Philadelphia 1998
- WHO Classification Tumours of the Lung, Pleura, Thymus and Heart.
Travis et al., ed. IARC Press 2004
- National Cancer Institute
Thymoma and Thymic Carcinoma - Health Professional version
https://www.cancer.gov/types/thymoma/hp
Images
images related to thymoma