Objective: To present a rare case report

Background: A 69 year old woman presented with progressive ptosis, change in voice (hypophonia), dysphagia, generalised weakness with fluctuations and fatiguability; which developed over a period of two weeks. She subsequently developed respiratory failure and had to put on mechanical ventilation. She had a history of lower respiratory tract infection and pulmonary thromboembolism 1 month prior to the presentation, from which she gradually recovered.

Method: On neurological evaluation, she seemed to have myasthenic syndrome with peripheral neuropathy, effecting predominantly lower limbs. Repeatitive nerve stimulation test at 3 Hz was positive; Acetyl choline receptor and MUSK receptor antibodies negative. In view of acute onset of the symptoms, she was evaluated, and autoimmune encephalitis and paraneoplastic antibody panel was negative. Whole body PET scan was negative, and lung biopsy was negative. MRI brain, spine, muscle was normal, CSF evaluation was normal.

Results: She was treated with intravenous immunoglobulins (IVIG), steroids, pyridostigmine, and showed improvement. She was weaned off the ventilator, dysphagia improved, and some improvement in ptosis and limb weakness. She remained in same state for next 3 months, followed by progressive worsening of weakness. She then developed abnormal involuntary movements in form of oro-lingual dyskinesias. Her nerve conduction study showed severe sensory and motor neuropathy. She then become encephalopathic. Serum paraneoplastic panel was sent again, and PNMA2 antibody titres were strong positive. CT chest was repeated and it showed presence of lung mass. Whole body PET scan was repeated and it now showed uptake in lung and mediastinal lymph nodes. MRI brain and CSF study was repeated but it did not reveal any abnormalities. Lung biopsy was repeated and was suggestive of adenocarcinoma of lung.

Conclusion: Hence we describe an unusual presentation of PNMA2 paraneoplastic syndrome with peripheral and CNS involvement in form of paraneoplastic myasthenic syndrome, sensory motor neuropathy, with later development of abnormal movements and encephalitis.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/unveiling-the-unusual-pnma2-paraneoplastic-syndrome/