Another case of sclerosing mediastinitis. The patient was a young female who presented with a mass in middle mediastinum. Histologic findings included dense fibrosis, chronic lympho-plasmacytic infiltrate, and widespread calcification. Many cases of chronic mediastinitis are caused by Histoplasma or Mycobacteria. In many cases, no cause can be ascertained (idiopathic sclerosing mediastinitis).