We report on a primary mediastinal large B-cell lymphoma with aberrant expression of β-human chorionic gonadotropin (β-hCG). The patient, a 33- year-old man, had cough, dyspnea, fever, superior vena cava syndrome, and a mediastinal bulky tumor. A biopsy showed that the latter was characterized by large cells, sclerosis, and compartmentalization. The neoplastic elements expressed CD45, CD20, CD79a and, partially, CD30, whereas they were negative for CD3, epithelial membrane antigen and cytokeratins. Surprisingly, they displayed a clear-cut positivity for β-hCG. The remaining oncofetal markers applied (PLAP and α1-fetoprotein) were negative. Electron microscopy demonstrated the presence of numerous nuclear pockets and the lack of intercellular junctions. DNA analysis by polymerase chain reaction showed clonal rearrangement of Ig heavy-chain genes. The patient responded promptly to the administration of MACOP-B. To the best of our knowledge, this is the first example of B-cell lymphoma showing positivity for β-hCG; a similar aberrant expression was previously observed only in three Japanese patients with human T-cell lymphotropic virus type I+ adult T-cell lymphoma/leukemia. Because primary mediastinal large B-cell lymphoma has in the past been frequently confused with germ cell tumors, pathologists should be aware of possible β-hCG expression by lymphomatous cells to avoid the risk of misdiagnosis.
- Electron microscopy
- Malignant lymphoma
- Molecular biology
ASJC Scopus subject areas
- Pathology and Forensic Medicine