Thymus, Thymoma, WHO Type A [LMP90597]

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Diagnostic Modality: 
Whole Slide Image
Disease Category: 
Neoplasia
Diagnosis: 
Thymoma, WHO Type A
Species: 
Human
Organ System: 
White Blood Cells, Lymph Nodes, Spleen, and Thymus
Gender: 
Male
Age: 
59 years
Diagnosis Code: 
ICD-10: D15.0 | ICD-O: 8581/1
Slide Contributor Information
Yang, H., Lu, F.

Keywords

thymus, thymic

Clinical History

Mediastinal mass.

Clinical Discussion

Thymomas are neoplasms of the thymic epithelial cells. Thymomas usually occur in adults and are typically discovered incidentally or from mass effect on mediastinal structures. Thymomas are associated with myasthenia gravis and may be discovered on workup for the disease.

Broadly, the WHO classifies thymomas based on the morphologic characteristics of the thymic epithelial cells and based on the presence of immature thymic lymphocytes. The main subtypes of thymoma include Type A, AB, B1, B2, B3, and thymic carcinoma.

The present case represents a type A thymoma, which is characterized by oval to spindled cells growing in a predominantly fascicular and microcystic pattern. The nuclei are bland with inconspicuous nucleoli. Type A thymomas are also characterized by the absence of admixed immature lymphocytes (which can be identified by immunohistochemistry for TdT and/or CD1a).

Type A thymomas overall have excellent prognosis with a low risk of recurrence if the tumour can be completely resected.

See Related Content for references:

1) Detterbeck FC., et al. JTO 9:S65-72, 2014

Related Content

Related External Links: 
Detterbeck FC, et al. The IASLC/ITMIG Thymic Epithelial Tumors Staging Project: proposal for an evidence-based stage classifi...