2024 American Academy of Neurology Abstract Website

Objective:

To highlight the potential of thymomas to metastasize and identify features that should prompt broader imaging in select patients.

Background:

Approximately 32% of thymomas are microscopically or grossly invasive, however extra-thoracic metastasis is rare. Current National Comprehensive Cancer Network guidelines for surveillance after thymoma resection are limited to thoracic CT scan.

Design/Methods:

We present the case of a patient who, years after thymoma resection, developed myasthenia gravis and was later found to have a large thymoma in the liver.

Results:

A 49 year old male professional truck driver with history of obesity, sleep apnea, and prostate cancer presented with 3 months pogressive diplopia on horizontal gaze. He had bilateral eye adduction palsy and ptosis, positive ice pack test, response to mestinon trial, positive AChR binding and blocking antibodies, and negative anti-striatal muscle antibodies. He was was diagnosed with seropositive ocular myasthenia gravis.

Of note, he presented to an ER with chest pain 6 years prior and x-ray revealed a mediastinal mass. Further imaging showed a 6 by 8 cm mass abutting the superior vena cava and right atrium. The thymoma was resected and pathological evaluation revealed type AB histology with macroscopic capsular invasion but confined within the mediastinal fat and negative regional lymph nodes. Afterward he received 54 Gy radiation.

CT thorax at time of myasthenia diagnosis demonstrated stable post-surgical changes. CT Abdomen revealed a 10.9 by 8 cm hepatic mass, which was eventually resected and pathologic evaluation showed type AB histology.

Conclusions:

Currently, only CT thorax is recommended for surveillance after thymoma resection. The presence of a new onset of myasthenia gravis in the absence of indicators of thymoma recurrence within the thorax should prompt additional investigations for distant metastasis.