Myasthenia gravis imitating pituitary apoplexy in macroprolactinoma

Area of Science:

• Neurology
• Endocrinology
• Autoimmune Diseases

Background:

• Myasthenia gravis (MG) is an autoimmune disorder impacting neuromuscular junctions, causing muscle weakness.
• Hyperprolactinemia is increasingly studied for its potential role in MG development, though its link to prolactinoma is exceptionally rare.
• Pituitary apoplexy (PA) is a critical complication in patients with pituitary macroadenomas.

Observation:

• A 71-year-old male with macroprolactinoma presented with acute neurological symptoms (headache, diplopia, ptosis) after initiating cabergoline treatment.
• Initial diagnosis suspected pituitary apoplexy, leading to emergency surgery, but symptoms persisted and worsened.
• Myasthenia gravis was suspected and confirmed via acetylcholine receptor antibodies, with prompt symptom improvement upon pyridostigmine treatment.

Findings:

• The patient's symptoms were initially misattributed to pituitary apoplexy but were ultimately caused by myasthenia gravis.
• Despite surgery and increased corticosteroid doses for suspected PA, neurological deficits persisted, highlighting the need for alternative diagnoses.
• Confirmation of acetylcholine receptor antibodies and response to pyridostigmine definitively diagnosed myasthenia gravis.

Implications:

• This case underscores the importance of considering myasthenia gravis in the differential diagnosis of patients with macroprolactinomas presenting with neurological symptoms.
• Early identification and treatment of myasthenia gravis can prevent misdiagnosis and delayed management in patients with pituitary tumors.
• Further research into the connection between hyperprolactinemia and myasthenia gravis pathogenesis is warranted.