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

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.