[Clinical analysis of reactive thymic hyperplasia following chemotherapy for childhood malignant lymphoma]

Reactive thymic hyperplasia following chemotherapy for malignant tumors is likely to be misdiagnosed as tumor residue or relapse, therefore, leads to unnecessary treatment. This study was to analyze the clinical features of reactive thymic hyperplasia following chemotherapy for childhood malignant lymphoma.

Clinical data of 13 children with reactive thymic hyperplasia following chemotherapy for malignant lymphoma, treated from Mar. 1999 to Mar. 2004, were retrospectively analyzed. Of the 13 cases, 5 were Hodgkin's disease (HD), and 8 were non-Hodgkin's lymphoma (NHL). All patients received computed tomography (CT) to evaluate the therapeutic effect. When a new thymic mass emerged, positive electron tomography/computed tomography (PET/CT) was performed to identify its quality.

At diagnosis, 10 patients had mediastinal involvement. Reactive thymic hyperplasia occurred following the completion of chemotherapy in 9 cases, or during the maintenance of chemotherapy in 4 cases. CT showed that the longest diameters of the new mediastinal masses were 2.2-6.0 cm (mean 3.7 cm). The interval from last chemotherapy cycle to the occurrence of thymic hyperplasia was 2-12 months (mean 4 months). PET/CT was performed to 5 cases, and showed no vital tumors in the mediastinum. Three cases were misdiagnosed as tumor residue or relapse, and received second-line therapy. All patients were followed-up for 1-6 years (median 4 years), and none suffered tumor relapse.

Reactive thymic hyperplasia may occur following intensive chemotherapy for childhood malignant lymphoma. It should not be misdiagnosed as malignant tumors and overtreated.