Follicular Dendritic Cell Sarcoma With Indolent T-Lymphoblastic Proliferation Is Associated With Paraneoplastic...

Area of Science:

• Hematology
• Immunology
• Oncology

Background:

• Nonclonal expansions of immature T cells outside the thymus, termed indolent T-lymphoblastic proliferation (iT-LBP), are rare lymphoproliferative disorders.
• Follicular dendritic cell sarcoma (FDCS) is a rare malignancy with diverse clinical presentations.

Purpose of the Study:

• To investigate the frequency of iT-LBP in FDCS.
• To determine the association between iT-LBP and paraneoplastic autoimmune multiorgan syndrome (PAMS) in FDCS patients.
• To understand the potential role of immature T cells in the pathogenesis of PAMS.

Main Methods:

• Paraffin immunohistochemistry on 31 FDCS cases using a panel of antibodies including TdT, CD3, CD4, CD8, CD20, CD1a.
• Chart review to assess clinical behavior and autoimmune disease manifestations.

Main Results:

• iT-LBP was identified in 14 of 31 (45%) FDCS cases.
• Five cases showed numerous immature TdT-positive T cells throughout the tumor.
• Four of these five patients developed PAMS and/or myasthenia gravis, with persistent autoimmune disease post-resection.

Conclusions:

• iT-LBP is a frequent finding in FDCS and is associated with PAMS.
• Neoplastic follicular dendritic cells may promote the proliferation of immature T cells.
• Immature T cells in FDCS may mediate PAMS, highlighting the importance of recognizing iT-LBP to avoid misdiagnosis and predict autoimmune complications.