Signet-ring cell variant of large cell lymphoma

Area of Science:

• Oncology
• Pathology
• Immunology

Background:

• Diffuse large B-cell lymphoma (DLBCL) is an aggressive non-Hodgkin lymphoma.
• Palatine tonsil lymphomas can exhibit diverse morphological presentations.
• Signet-ring cell morphology in lymphoma is uncommon and requires detailed characterization.

Observation:

• A case of palatine tonsil lymphoma displayed numerous enlarged tumor cells with distinctive cytoplasmic inclusions.
• These inclusions displaced the nucleus, mimicking signet-ring cell morphology.
• The inclusions were hyaline and resembled Russell bodies.

Findings:

• Immunoperoxidase staining confirmed the cytoplasmic inclusions were positive for mu heavy chains and kappa light chains.
• This immunophenotype is characteristic of a B-cell lineage, specifically indicating immunoglobulin M (IgM) production.
• Ultrastructural analysis revealed the inclusions were crystalloids within the rough endoplasmic reticulum.

Implications:

• This case expands the known morphological spectrum of DLBCL.
• The findings highlight the importance of immunophenotyping and ultrastructural studies for accurate diagnosis of rare lymphoma subtypes.
• Understanding the origin of these inclusions may offer insights into B-cell differentiation and oncogenesis.