Extrathymic malignancies in a defined cohort of patients with myasthenia gravis.

Introduction: Myasthenia gravis (MG) may be associated with extrathymic malignancies, especially in patients with thymoma.
Aim: To determine the frequency and type of extrathymic malignancies in MG patients from the Belgrade area, and to identify potential risk factors associated with tumors.
Patients and Method: The study comprised 390 patients with MG. Different sociodemographic and clinical variables potentially associated with extrathymic neoplasms were analyzed.
Results: Extrathymic malignancies were present in 42 (10.8%) MG patients - 22 (52.4%) males and 20 (47.6%) females. The most frequently detected were breast (40%) and lung (40%) neoplasms. The tumors appeared with similar frequency before (45.2%) and after the onset of MG (42.9%). Significant predictors for the development of extrathymic malignancies were current age (p = 0.001) and immunoglobulin (IVIg) therapy (p = 0.021). On the other hand, current age (p=0.001), longer MG duration (p = 0.001) and generalized form of MG (p = 0.002) were significant predictors of malignancy occurring after the MG onset.
Conclusion: Our study revealed that older MG patients, as well as those with longer duration of the disease, and those who received IVIg therapy had a higher oncogenic risk for the development of extrathymic malignancies.
(Copyright © 2014 Elsevier B.V. All rights reserved.)