Enlarged mediastinal shadow: not always lymphoma

Introduction:

Mediastinal widening on chest X-ray is an alarming finding that requires further investigation. In infants and young children, it usually reflects physiological thymic enlargement. In older children, however, it may result from germ cell tumors, thymic disease, infections, vascular anomalies, or hematopoietic malignancies. We present three pediatric cases in which proliferative disorders of the hematopoietic and lymphatic systems manifested as very similar mediastinal enlargement on radiographs.

Case reports:

Case 1: A 14-year-old girl presented with fever, pruritus, and neck contour changes. Examination revealed hard, painless lymphadenopathy in the supraclavicular and cervical regions. Laboratory tests showed leukocytosis of 13,000/µl, hemoglobin 11.1 g/dl, and platelets 405,000/µl. Chest X-ray demonstrated a mediastinal shadow of 105 mm. Histopathology confirmed stage IVB Hodgkin’s lymphoma, nodular sclerosis subtype.

Case 2: An 11-year-old boy was admitted with progressive dyspnea, cough, and neck swelling lasting one month. Chest X-ray revealed mediastinal widening of 83 mm, narrowing the airway to 1 mm. Due to respiratory failure, tracheostomy and biopsy were performed. Laboratory results showed leukocytosis of 10,100/µl and elevated D-dimers. Final diagnosis was stage IV T-cell lymphoblastic lymphoma.

Case 3: A 13-year-old boy presented with gastrointestinal bleeding and generalized petechiae. Ultrasound revealed splenomegaly. Laboratory findings included hyperleukocytosis (170,000/µl) with 80% blasts, thrombocytopenia (23,000/µl), and elevated transaminases. Physical exam showed hepatosplenomegaly and generalized lymphadenopathy. Chest X-ray demonstrated mediastinal widening of 77 mm. Myelogram and immunophenotyping confirmed acute T-cell lymphoblastic leukemia.

Conclusions:

Although chest X-ray is an important initial tool, it cannot differentiate the causes of mediastinal widening. In adolescents with alarming symptoms, further evaluation with blood counts, imaging, and histopathology is essential. These cases demonstrate that nearly identical radiological appearances may correspond to distinct hematologic malignancies, each requiring targeted treatment.