Disclosures: Xiaomeng Li, MD: No financial relationships or conflicts of interest

Case Description: An otherwise healthy 41 year old female began to have right calf cramping when running. She presented to an outside emergency department soon after symptom onset and lower extremity duplex was negative for deep vein thrombosis. She had worsening weakness of her right lower extremity over the next two weeks, endorsing difficulty climbing stairs and standing from seated. Her internist ordered magnetic resonance imaging (MRI) of the lumbar spine, which was unremarkable. At evaluation for electrodiagnostic studies three weeks after symptom onset, examination of the right leg showed subtle weakness at the knee, remarkable weakness at the ankle in all directions, and decreased light touch at S1, with decreased pinprick at L4-L5. Reflexes were reduced at the patellar and Achilles tendons compared to contralateral side. There was no palpable mass at the popliteal fossa nor posterior thigh.

Setting: tertiary acute care hospital

Patient: 41 year old female with history of idiopathic neutropenia Assessment/

Results: Nerve conduction study revealed normal, symmetric motor and sensory studies. Electromyography (EMG) showed severely decreased recruitment of the tibialis anterior, gastrocnemius, peroneus longus, tibialis posterior, and flexor digitorum longus muscles. EMG examinations of the biceps femoris short head, gluteus medius, and tensor fascia lata muscles were normal. Subsequently, a right femur radiograph was obtained, which appeared normal. MRI of the right thigh showed a 21 x 23 x 50 mm sciatic mass. Biopsy of the mass demonstrated diffuse large B-cell lymphoma.

Discussion: The patient experienced rapid-onset distal extremity motor and sensory deficits over several weeks with negative lumbar imaging. Electrodiagnostic studies revealed abnormalities most consistent with a sciatic nerve distribution, helping target additional advanced imaging, leading to more rapid diagnosis. The patient will undergo chemotherapy treatment.

Conclusion: Electrodiagnostic studies are a useful tool to complement history and imaging for lesion localization in focal weakness when used within the appropriate timeframe.

Level of Evidence: Level V

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PM&R Meeting Abstracts - https://pmrjabstracts.org/abstract/presentation-of-diffuse-b-cell-lymphoma-as-a-sciatic-nerve-tumor-localized-on-electrodiagnostic-study-a-case-report/