Massive thymic hyperplasia in a 15-month-old boy: Case report and literature review

Massive true thymic hyperplasia with osseous metaplasia

True thymic hyperplasia is defined as an increase in both the size and weight of the gland, while maintaining a normal microscopic architecture. Massive true thymic hyperplasia is a rare type of hyperplasia that compresses adjacent structures and causes various symptoms. Limited reports address the imaging findings of massive true thymic hyperplasia. Herein, we report a case of massive true thymic hyperplasia in a 3-year-old girl with no remarkable medical history. Contrast-enhanced CT revealed an anterior mediastinal mass with a bilobed configuration containing punctate and linear calcifications in curvilinear septa, which corresponded to lamellar bone deposits in the interlobular septa. To our knowledge, this is the first report of massive true thymic hyperplasia with osseous metaplasia. We also discuss the imaging features and etiology of massive true thymic hyperplasia with osseous metaplasia.

Case report: Imaging findings of true thymic hyperplasia at 18F-FDG PET/CT in an infant

True thymic hyperplasia (TTH) in children is rare and difficult to distinguish from other thymic tumors such as thymoma and thymic carcinoma. A 3-year-old girl underwent an ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/computed tomography (CT) scan (¹⁸F-FDG PET/CT) and a chest CT scan to evaluate an anterior mediastinal mass. ¹⁸F-FDG PET/CT revealed a mediastinal mass showing heterogeneously increased FDG uptake with a maximum standardized uptake value (SUVmax) of 7.1. Eventually, postoperative pathological diagnosis demonstrated TTH. So far, there are no reports of ¹⁸F-FDG PET/CT imaging of this disease.

Thoracoscopic approach for massive thymic hyperplasia in an infant: Case report and literature review

Introduction

Massive thymic hyperplasia (MTH) is a very rare entity, with fewer than 20 cases reported in the literature in infancy. Most patients have respiratory symptoms and the enlarged thymus gland occupies one side of the thoracic cavity. Posterolateral thoracotomy or median sternotomy is the main treatment for MTH in infants. We report a case of an infant with MTH in which the enlarged thymus occupied his bilateral thoracic cavity and he underwent video-assisted thoracoscopic surgery (VATS). In addition, we reviewed and summarized the relevant literature.

Case Report

A 4-month-old boy was admitted to the hospital with no apparent cause of dyspnea for 18 days, with cough and sputum. On examination, the patient was found to have cyanotic lips, diminished breath sounds in both lungs, and a positive three concave sign. There was no fever or ptosis. Preoperative imaging showed large soft tissue shadows in the bilateral thoracic cavity, with basic symmetry between the right and left sides. Tumor markers were within the normal range. Ultrasound-guided fine needle biopsy showed normal thymic structures with no evidence of malignancy. As his symptoms worsened, he eventually underwent unilateral thoracic approach video-assisted thoracoscopic exploratory surgery, during which a large mass occupying the bilateral thoracic cavity was removed in a separate block and part of the thymus in the left lobe was preserved. Pathological examination confirmed true thymic hyperplasia (TTH). No relevant complications occurred at the 2-month postoperative follow-up.

Conclusion

In infants, MTH occupying the bilateral thoracic cavity can produce severe respiratory and circulatory symptoms due to occupying effects. Although a definitive preoperative diagnosis is sometimes difficult, after combining computed tomography (CT) and fine needle biopsy to exclude evidence of other malignancies, the enlarged thymus occupying the bilateral thoracic cavity can be resected via VATS. Whether the enlarged thymus occupies the bilateral thoracic cavity and the size of the thymus are not absolute contraindications to thoracoscopic surgery. The method is safe, feasible, and minimally invasive to the patient.

True thymic hyperplasia causing pure red cell aplasia: a case report

Pure red cell aplasia caused by true thymic hyperplasia is extremely rare. We report the case of a 25-year-old female diagnosed with pure red cell aplasia. Following a thymectomy confirming true thymic hyperplasia and corticosteroid therapy, complete response was achieved. Patients diagnosed with pure red cell aplasia should be investigated with a computerized tomographic scan to assess for thymic pathology and if present, this should be resected. Follow-up is essential to monitor for recurrence.