Ki-1-positive non-Hodgkin's lymphomas. An immunophenotypic, ultrastructural, and morphometric study

Area of Science:

• Hematopathology
• Oncology
• Cell Biology

Background:

• Diffuse large cell non-Hodgkin's lymphomas (DLBCL) are aggressive lymphoid malignancies.
• Ki-1 (CD30) expression is a key marker in certain lymphoma subtypes.
• Understanding the cellular origins and characteristics of Ki-1 lymphomas is crucial for diagnosis and treatment.

Purpose of the Study:

• To investigate ultrastructural and morphometric features of four diffuse large cell non-Hodgkin's lymphomas with strong Ki-1 expression.
• To determine if these Ki-1 lymphomas share common cellular characteristics.
• To explore potential histiocytic differentiation markers in Ki-1 lymphomas.

Main Methods:

• Electron microscopy was used to analyze ultrastructural features of tumor cells.
• Morphometric analysis quantified nuclear size and membrane irregularity (nuclear contour index).
• Immunophenotyping assessed cell surface markers to determine lineage and activation status.

Main Results:

• Tumor cells exhibited abundant cytoplasm with concentrated organelles and frequent reniform nuclei.
• One case displayed complex "microvillous" cytoplasmic projections.
• Nuclear area was approximately twice that of small lymphocytes, with increased nuclear membrane irregularity compared to typical large cell lymphomas.
• Immunophenotypes were variable, showing activation markers and abnormal T-cell patterns.

Conclusions:

• Ki-1 lymphomas represent a heterogeneous group of lymphoid tumors.
• Ultrastructural findings suggest potential histiocyte differentiation, though immunophenotypes are variable.
• These lymphomas display hybrid features, bridging lymphoid and histiocytic characteristics.