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4 slides generated from the cancer page, with a quiz from the open benchmark and speaker notes that cite the sources. Arrow keys move between slides; Print gives one slide per page.
Type B1 and type B2 thymoma are thymus gland tumours in which the epithelial tumour cells are mixed with many immature lymphocytes, resembling the normal thymic cortex; B2 is the commonest thymoma of all. They are strongly linked to myasthenia gravis, are usually cured by surgery, and get radiotherapy when they have grown beyond the gland or could not be fully removed.
Types B1 and B2 sit between the indolent A and AB thymomas and the aggressive B3 in the WHO classification; B1 resembles normal thymic cortex with sparse epithelial cells and B2 has clusters of epithelial cells among the lymphocytes, and the ITMIG consensus set criteria for distinguishing B1, B2 and B3 (Marx 2014). In the worldwide database type B2 was the most common histotype (28 percent), the B types presented at higher stages than A and AB, and recurrence after resection for B1 to B3 was 2 to 7 percent, with age, stage and resection status the multivariate predictors of survival and histology affecting recurrence (Weis 2015). Myasthenia gravis and other paraneoplastic autoimmunity are most frequent with the B types.
How it differs from its parent: the lymphocyte-rich histology can be mistaken for lymphoma or normal thymus on biopsy, the association with myasthenia gravis shapes perioperative care, and the B types more often present at Masaoka-Koga stage II or III than types A and AB.
| Setting | Approach | Guideline |
|---|---|---|
| All stages | Complete resection; postoperative radiotherapy for stage III or incomplete resection; platinum-based chemotherapy for unresectable or metastatic disease, as on the parent page. | not mapped |