The role of PET-CT in the differential diagnosis of thymic mass after treatment of patients with lymphoma

Thymic hyperplasia is a common phenomenon in both children and young adults after chemotherapy and may explain the finding of a mediastinal mass in patients with malignant lymphoma after complete remission. In the present study, we report 5 cases with malignant lymphoma presenting with a mediastinal mass on CT scan after completion of chemotherapy diagnosed as thymic hyperplasia by PET-CT imaging. We retrospectively analyzed 5 patients who presented with anterior mediastinal masses a median of 4 months (range 3–6) after achieving complete remission following successful treatment for malignant lymphoma. Three patients were diagnosed with Hodgkin’s lymphoma (HL) and the others with non-Hodgkin’s lymphoma (NHL). The median age of the patients was 23 (range of 18–47). PET-CT was performed on these patients to determine the characteristics of a mass which had been detected on CT. PET-CT was performed for all patients, and the thymic masses demonstrated only mild FDG uptake considered to be consistent with thymic hyperplasia. During a median of 24 months of follow-up, all patients were recurrence-free with a median survival of 15 months (range 10–26 months). It is important to be aware of the possibility of thymic hyperplasia after chemotherapy to avoid misdiagnosis or over-staging of disease, as well as unnecessary biopsies, especially when the presenting anterior mediastinal mass was originally located near the thymus on CT scan. Mild FDG PET uptake was sufficient for the diagnosis of benign disease in the cases in this study.     

Does Specific Immunotherapy Injection Cause an Increase in Bronchial Reactivity?

Background. Several well-controlled studies have proven the clinical benefit of specific immunotherapy (SIT) for seasonal allergic rhinitis (AR). However, whether subcutaneous SIT injection could cause a transient increase in bronchial reactivity (BR) remains unknown. Objective. To investigate whether subcutaneous SIT injection, either during or outside the pollen season, could cause an increase in BR in children with pollen allergy. Methods. Twenty-two children (mean age 13.6 ± 0.7 years) with AR who were receiving maintenance SIT for 15 months were included in the study. Pre-injection BR of the patients was evaluated with methacholine provocation test immediately before maintenance dose of SIT during the peak pollen season and outside the season. The post-injection test was administered 24 hours after SIT injection. Results. There was no difference in FEV₁ measures recorded during [98(93-109)%] and outside [102(96-111)%] the pollen season. There was no significant difference between pre- [64(7-64)mg/mL] and post-allergen injection [32(7.5-64) mg/mL] BR outside the pollen season (p = 0.9). A trend towards improvement following allergen injection [64(5.4-64)] as compared to pre-allergen injection [14.6(3.5-64)] was shown during the pollen season (p = 0.053). Although PC20 measures in the pollen season were lower than outside the season, the difference was not significant. The percentage of the patients with bronchial hyperreactivity was 62% during and 43% outside the season. Conclusion. SIT injections both during and outside the pollen season cause no increase in BR in children with AR. This calls into question the necessity of empirical dose reduction during the pollen season.     

Incorrect Application Technique of Metered Dose Inhalers by Internal Medicine Residents: Impact of Exposure to a Practical Situation

Background. Several well-controlled studies have proven the clinical benefit of specific immunotherapy (SIT) for seasonal allergic rhinitis (AR). However, whether subcutaneous SIT injection could cause a transient increase in bronchial reactivity (BR) remains unknown. Objective. To investigate whether subcutaneous SIT injection, either during or outside the pollen season, could cause an increase in BR in children with pollen allergy. Methods. Twenty-two children (mean age 13.6 ± 0.7 years) with AR who were receiving maintenance SIT for 15 months were included in the study. Pre-injection BR of the patients was evaluated with methacholine provocation test immediately before maintenance dose of SIT during the peak pollen season and outside the season. The post-injection test was administered 24 hours after SIT injection. Results. There was no difference in FEV₁ measures recorded during [98(93–109)%] and outside [102(96–111)%] the pollen season. There was no significant difference between pre- [64(7–64)mg/mL] and post-allergen injection [32(7.5–64) mg/mL] BR outside the pollen season (p = 0.9). A trend towards improvement following allergen injection [64(5.4–64)] as compared to pre-allergen injection [14.6(3.5–64)] was shown during the pollen season (p = 0.053). Although PC20 measures in the pollen season were lower than outside the season, the difference was not significant. The percentage of the patients with bronchial hyperreactivity was 62% during and 43% outside the season. Conclusion. SIT injections both during and outside the pollen season cause no increase in BR in children with AR. This calls into question the necessity of empirical dose reduction during the pollen season.