Conjunctival Pediatric-Type Follicular Lymphoma

Area of Science:

• Oncology
• Ophthalmology
• Hematology

Background:

• Pediatric-type follicular lymphoma (PTFL) is a rare B-cell neoplasm typically affecting pediatric and young adult head and neck lymph nodes.
• Ocular involvement by PTFL is exceptionally rare, with only five prior conjunctival cases documented.

Purpose of the Study:

• To report a rare case of conjunctival PTFL in a young adult.
• To detail the clinical presentation, pathological findings, and molecular characteristics of this unusual ocular lymphoma.

Main Methods:

• Clinical examination and excisional biopsy of conjunctival nodules.
• Immunohistochemistry (CD20, CD10, BCL6, BCL2), polymerase chain reaction (PCR) for immunoglobulin heavy chain rearrangement, fluorescence in situ hybridization (FISH), and next-generation sequencing (NGS).

Main Results:

• Biopsy revealed PTFL with characteristic germinal center morphology and immunophenotype (CD20+, CD10+, BCL6+, BCL2-).
• PCR confirmed a monoclonal B-cell population.
• NGS identified a pathogenic MAP2K1 mutation, a known genetic driver in PTFL.

Conclusions:

• Conjunctival PTFL is a rare but distinct entity that can mimic benign lesions like pyogenic granuloma.
• Molecular profiling, particularly identifying MAP2K1 mutations, is crucial for accurate diagnosis and understanding the pathogenesis of PTFL.
• This case expands the known spectrum of ocular involvement in PTFL and underscores the importance of comprehensive diagnostic workup for conjunctival masses.