Metachronous multiple thymoma with different clinical behavior and pathological findings

Area of Science:

• Thoracic oncology
• Pathology
• Surgical oncology

Background:

• Thymoma is a rare tumor originating from the thymus.
• Multicentric thymoma, with multiple distinct primary tumors, is exceptionally rare.

Observation:

• A 70-year-old woman presented with sequential development of two distinct masses in the left hilum.
• Initial nodule identified on chest radiograph 3 years prior, followed by a second mass.
• Surgical resection revealed an encapsulated rostral nodule and a caudal mass invading the left lung.

Findings:

• Histological examination identified the rostral nodule as a stage 1 type B2 thymoma.
• The caudal mass was diagnosed as a stage 3 type B3 thymoma.
• Significant differences in tumor encapsulation, invasiveness, and histological subtype were noted.

Implications:

• The distinct characteristics suggest a multicentric origin rather than intrapulmonary metastasis.
• This case highlights the importance of thorough pathological evaluation for thymic neoplasms.
• Understanding multicentric thymoma origins can inform future diagnostic and treatment strategies.