Recurrent mediastinal mass in a child with Hodgkin's disease following successful therapy: a diagnostic challenge

The case of an 11-year-old girl with mediastinal stage III B-E Hodgkin's disease is described. She achieved complete remission with combined chemoradiotherapy according to the Swiss Pediatric Oncology Group-HD Protocol 1985. Six months after all therapy was stopped, a slowly growing retrosternal mass was detected. Computed tomography (CT) and gallium-67 single-photon emission CT (SPECT) could not elucidate the true origin of the tumor, nor did ultrasound-guided transthoracic fine-needle puncture. Open biopsy with histologic examination of the lesion has successfully identified the mass as thymic hyperplasia, a rebound immunologic reaction after chemoradiotherapy that mimicked tumor regrowth.