To describe a case of neurolymphomatosis with peripheral T-cell lymphoma mimicking an acquired demyelinating polyneuropathy.

Neurolymphomatosis is a rare clinical entity characterized by the infiltration of the cranial or peripheral roots or nerves by the lymphoid cells. It is predominantly seen with non-Hodgkin’s lymphoma and involves B-lymphoid cells. T-cell lymphoma involving the peripheral nerves is relatively rare.

A 49-year-old man presented with three months of painless, progressive bilateral foot drop and left wrist drop with asymmetric numbness in bilateral feet. This was preceded by a diffuse rash three months ago which improved with topical steroids. Serum and urine protein electrophoresis and autoimmune workup, including anti-MAG and anti-GM1 antibodies was normal.

Nerve conduction studies demonstrated conduction blocks at non-entrapment sites. Multifocal nerve enlargement was noted on neuromuscular ultrasound. He was diagnosed with multifocal acquired demyelinating sensory and motor polyneuropathy (MADSAM) and was started on intravenous immunoglobulins.

His weakness continued to progress and he developed an erythematous, desquamated rash over the dorsum of hands. PET scan was unrevealing. Bone marrow biopsy detected abnormal population of CD3-, CD4+ T cells without definitive evidence of T-cell lymphoproliferative process. Nerve biopsy again demonstrated CD4+, CD3- neoplastic T-cells. Inguinal node biopsy demonstrated multiple granulomas, polyclonal plasmacytosis and atypical CD3-, CD4+ cell population. He was diagnosed with cutaneous peripheral T-cell lymphoma and started on chemotherapy. He developed CNS involvement and died within one year of symptom onset.

T-cell neurolymphomatosis is a unique manifestation of extranodal lymphoma. An asymmetric sensory and motor demyelinating neuropathy is an unusual initial presentation. If neuropathy is the presenting symptom, the diagnosis of lymphoma can be challenging and is often delayed. High clinical suspicion is needed and neurolymphomatosis should be in the differentials of a demyelinating neuropathy, especially with poor response to initial treatment.