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.