Very rare solitary primary peripheral nerve onset cytotoxic molecule‐positive peripheral T‐cell lymphoma ( <scp>PTCL</scp> )

Here we present the first report of solitary primary peripheral nerve onset cytotoxic molecule (CM)-positive peripheral T-cell lymphoma (PTCL) diagnosed after nerve biopsy. An 84-year-old female with rheumatoid arthritis (RA) complained of asymmetric severe tenderness in her upper limbs. The biopsy pathology revealed a direct invasion of CM-positive PTCL. When RA patients complain of numbness, tenderness, or weakness, lymphomatic peripheral nerve invasion should be considered.