Thymoma is strongly associated with myasthenia gravis (MG), particularly at the onset of the disease 1 . Thymus investigation in MG patients is typically recommended at the onset of MG or when patients present with clinical deterioration or a progressive increase of anti-acetylcholine receptor (AChR) antibody 2,3 . However, it is unknown if repeated screenings for thymoma at fixed intervals, even in the absence of MG deterioration, are necessary when the initial screening is negative. In addition, therapeutic guidelines do not mention the importance of thymus follow-up if the initial screening is negative 1,4 .The main objective of this study was to determine the recurrence rate and incidence of new thymoma in a series of MG patients without clinical deterioration who underwent long-term follow-up.
METHODSWe included MG patients who fulfilled the following criteria: (1) diagnosis based on abnormal repetitive nerve
ABSTRACTThymoma screening is recommended at the onset of myasthenia gravis (MG) or when patients with MG present with clinical deterioration or a progressive increase of anti-acetylcholine receptor antibody. However, it is unknown if it is necessary to repeat the screening of thymoma at fixed intervals, even in the absence of MG deterioration, when the initial screening is negative. We analyzed the recurrence rate and incidence of new thymoma in a series of patients with well-controlled MG. The sample consisted of 53 patients, aged 17 to 72 years, and the follow-up varied between 75 and 472 months. The chest computerized tomography detected thymus abnormalities in eight patients at the initial screening and no abnormalities in all patients at a second screening after five years. The findings of this study support the classical opinion that screening for thymoma should be recommended only if there is clinical deterioration due to the disease.Keywords: myasthenia gravis, thymus gland, thymoma, tomography.
RESUMOA investigação de timoma é recomendada em pacientes com miastenia gravis (MG) no início da doença, em caso de haver piora clínica ou aumento dos níveis do anticorpo antirreceptor de acetilcolina. Contudo, não foi estabelecido se é necessário repetir a investigação de timoma em intervalos fixos, na ausência de piora clínica, quando a investigação inicial foi negativa. A taxa de recorrência e a incidência de novo timoma foram analisadas em uma série de pacientes com MG bem controlada. A amostra consiste de 53 pacientes, idade entre 17 e 72 anos, com tempo de acompanhamento variando entre 75 e 472 meses. A primeira tomografia computadorizada de tórax detectou anormalidades no timo em oito pacientes durante a investigação inicial da doença e nenhuma anormalidade no segundo exame, após cinco anos de doença, em todos os pacientes. Os achados desse estudo corroboram a clássica opinião de que a investigação de timoma deveria ser recomendada somente se houver piora clínica da doença.