Ki-1-positive lymphoma developing 10 years after the diagnosis of hairy cell leukemia

Area of Science:

• Hematology
• Oncology
• Immunology

Background:

• Hairy cell leukemia (HCL) is a rare B-cell chronic lymphoid leukemia.
• Coexistence of HCL with other lymphoid neoplasms, including Hodgkin's disease and non-Hodgkin's lymphoma, has been previously reported.
• Ki-1-positive lymphoma, also known as anaplastic large-cell lymphoma (ALCL), is a distinct type of non-Hodgkin's lymphoma.

Observation:

• A 62-year-old male with a 10-year history of HCL developed a Ki-1-positive lymphoma.
• Immunocytochemical staining of lymph node biopsy showed tumor cells positive for Ki-1 (CD30) and epithelial membrane antigen.
• Flow cytometry revealed simultaneous expression of Leu M5 (CD11c) and Leu 14 (CD22) on tumor cells.

Findings:

• This case represents the first reported instance of a Ki-1-positive lymphoma arising in a patient with pre-existing HCL.
• The immunophenotype of the lymphoma included CD30, EMA, CD11c, and CD22.
• The study discusses the clinicopathologic and immunologic features of both HCL and Ki-1-positive lymphoma.

Implications:

• This rare association expands the understanding of potential neoplasms that can develop in patients with HCL.
• Further research may elucidate shared pathogenetic mechanisms or risk factors between HCL and Ki-1-positive lymphoma.
• Highlights the importance of comprehensive immunophenotypic analysis in patients with a history of HCL who develop new lymphoid malignancies.