Primary gastric natural killer/T-cell lymphoma with diffuse CD30 expression and without CD56 expression: A case...

Area of Science:

• Oncology
• Hematopathology
• Immunology

Background:

• Natural killer (NK)/T-cell lymphomas typically manifest in the nasal cavity and rarely affect the stomach.
• Standard immunophenotype includes CD56, CD2, and CD3ε expression, with absent CD3 expression.
• Partial CD30 expression is infrequently observed in NK/T-cell lymphomas.

Purpose of the Study:

• To document a unique case of gastric NK/T-cell lymphoma with an atypical immunophenotype.
• To highlight the diagnostic challenges posed by unusual presentations of NK/T-cell lymphoma.
• To contribute to the understanding of rare extranodal lymphomas.

Main Methods:

• Histopathological examination of a gastric tumor biopsy.
• Immunohistochemical staining for a panel of markers including CD3ε, CD43, CD30, granzyme B, CD2, CD4, CD5, CD7, CD8, CD56, ALK, CD20, PAX5, and pan-cytokeratin.
• Epstein-Barr virus (EBV) RNA in situ hybridization.

Main Results:

• The tumor cells expressed CD3ε, CD43, CD30, and granzyme B.
• The tumor cells lacked expression of CD2, CD4, CD5, CD7, CD8, and CD56.
• Epstein-Barr virus (EBV) RNA was diffusely positive in the tumor cells.
• The case presented with diffuse CD30 positivity and CD56 negativity, deviating from the typical NK/T-cell lymphoma profile.

Conclusions:

• This is the first reported case of gastric NK/T-cell lymphoma exhibiting a diffuse CD30-positive and CD56-negative phenotype.
• The atypical immunophenotype initially suggested gastric anaplastic large cell lymphoma, underscoring the importance of EBV testing in gastric lymphomas.
• Accurate diagnosis requires careful integration of morphology, immunophenotype, and molecular findings, especially in rare extranodal presentations.