Myasthenia gravis unmasked by imatinib

Abstract

A 40-year-old man presented with drooping of both eyelids and generalized weakness of two weeks duration. The symptoms were worse during the evening. He had been diagnosed with chronic myeloid leukaemia (CML) in chronic phase, four months previously, and was receiving regular imatinib, 400 mg/day. After three weeks of therapy, he had achieved a complete haematological response, and his constitutional symptoms had subsided. After three months of therapy, he showed a two-log reduction of BCR-ABL1 transcript. On presentation, he had bilateral ptosis (left). Physical examination was otherwise normal. A provisional diagnosis of ocular myasthenia gravis was made. He showed improvement in ptosis after administration of neostigmine. Repetitive nerve stimulation and anti-acetylcholine receptor antibody serology were positive, confirming the diagnosis of myasthenia gravis. He was started on pyridostigmine and prednisolone. Computed tomography of his chest showed a 2Á7 9 1Á7 cm mass in the anterior mediastinum, for which he underwent thymectomy. Histopathological examination showed thymic hyperplasia. He is currently asymptomatic with marked improvement in ptosis (right) and has achieved a partial molecular response (BCR-ABL1 transcript level, 1Á113%).Many cases of drug-induced myasthenia gravis have been reported. Drugs implicated include ribavirin, statins, fluoroquinolones, interferon, fludarabine, chloroquine, penicillamine, busulfan and carbamazepine. Development of myasthenia gravis during treatment with nilotinib has also been reported in a patient with CML. In the current case, myasthenia gravis was unmasked when the patient was treated with imatinib. Triggering of myasthenia by tyrosine kinase inhibitors and certain other drugs may be related to a disturbance of immune function. However, other possibilities, including a paraneoplastic manifestation of CML or co-incidental occurrence of myasthenia gravis and CML, cannot be ruled out.

Priapism in Chronic Myeloid Leukemia: Meeting at the Crossroads and Heading in Different Directions

“…The reported incidence of impotence on detumescence in patients presenting late with low-flow priapism is >50%. [8] The present finding suggests that though priapism is low flow (ischemic) in CML, it has a milder phenotype and better outcome in comparison to other types of low-flow priapism.…”

“…[7] The treatment modalities recommended include immediate medical management (hydroxyurea and analgesia), hydration, and TKI (imatinib) (on confirmation of CML). [8] Apart from systemic treatment, it has been described that local intracavernous therapy in the form of penile aspiration, instillation of sympathomimetic drugs such as phenylephrine, and penile shunt procedures are also beneficial in bringing down the penile swelling. [9,10] Penile biopsy is not recommended in CML with priapism.…”

Neuromuscular complications following targeted therapy in cancer patients: beyond the immune checkpoint inhibitors. Case reports and review of the literature

“…A mediastinal mass was identified and resulted in thymic hyperplasia. The authors concluded that MG was unmasked by Imatinib, related to a disturbance of the immune function, but they could not rule out co-incidental occurrence of MG and LMC or a paraneoplastic manifestation of LMC [14]. Nevertheless, to our opinion, the presence of thymic hyperplasia should not be overlooked.…”

Myasthenia Gravis and Myeloproliferative Neoplasms – Mere Association or Paraneoplastic Neurologic Syndrome: A Mini-Review

“…The earliest reports were of 2 CML patients who developed MG after several years of treatment with busulfan. A summary of all cases of MPNs associated with MG is presented in Table 1 [14][15][16][17][18][19][20][21][22][23][24][25].…”

“…The authors of many reports had associated the onset of MG symptoms with the use of drugs to treat MPNs. Eg: TKI in [16], [17] and [18], busulfan in [24], [25] and [26], and interferon-alpha in [21]. However, there is no clarity in the mechanism of drug-induced MG in these reports.…”