Abstract
Generalized lymphatic anomaly (GLA) is an infrequent multiorgan disease characterized by the presence of abnormal proliferation of lymphatic vessels. The diagnosis requires histological confirmation, and the treatment is controversial. We are presenting a case of a 28-year-old male patient who was diagnosed with an extragonadal mediastinal nonseminomatous germ cell tumor. He underwent chemotherapy, and during this treatment, radiologic findings evidenced lytic lesions. Multiple biopsies were performed, which revealed the presence of abnormal lymphatic vessels, characteristic of GLA. There are different etiologies of osteolytic lesions, and on some occasions, they mimic a tumoral entity. The clinical suspicion of GLA is the first step in approaching the diagnosis, particularly in young adult patients.