History and exam

Key diagnostic factors

common

10% to 15% of patients with myasthenia gravis have an associated thymoma.[8]

Suggests myasthenia gravis. Ocular weakness (double vision, drooping eyelids) may be the only presenting feature. Generalized weakness, particularly facial and oropharyngeal weakness (difficulty chewing, dysphagia, or dysarthria), as well as proximal limb weakness (difficulty with getting out of chairs or climbing stairs) may be present. In patients with myasthenic crisis, respiratory muscle weakness results in severe respiratory involvement.

uncommon

Suggests superior vena cava syndrome. May also occur in lymphoma and germ cell tumors.

Suggests superior vena cava syndrome. Due to venous engorgement and edema.

Suggests superior vena cava syndrome.

Due to invasion and obstruction of the left innominate vein.

Other diagnostic factors

uncommon

Usually mild and nonproductive without hemoptysis. May also occur in lymphoma and germ cell tumors.

Nonspecific symptom; usually mild. Marked dyspnea, particularly when supine or flexed at the waist, can be due to phrenic nerve invasion with elevated, dysfunctional hemidiaphragm. May also occur in lymphoma and germ cell tumors.

Rare, nonspecific systemic symptoms. Fever and/or weight loss are common in lymphoma.

Risk factors

strong

10% to 15% of patients with myasthenia gravis have an associated thymoma.[8]

weak

The peak age of incidence of a thymoma is between 45 and 65 years; the mean age for thymic carcinoma is 46 years.[8] The age of the patient can be useful in discriminating between thymoma and lymphoma because lymphoma usually arises in patients aged under 35 years or over 65 years. Thymoma in patients under the age of 40 is uncommon.[17]

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