title: Unusual lesions of the mediastinum.
abstract: OBJECTIVE
  To study unusual lesions in the mediastinum, which do not originate from the thymus, lymph nodes, neural tissues or germ cells, and tissues that normally engender pathologic lesions in the mediastinum.
  
  
  METHODS
  Of the 65 cases seen, 12 unusual lesion were encountered in a 5½ year period from 2006 to 2011.
  
  
  RESULTS
  Two cases of nodular colloid goiter and one each of the mediastinal cyst, undifferentiated carcinoma, and Langerhans cell histiocytosis (LCH) affected the anterosuperior mediastinum. In the middle mediastinum, one case each of the mesothelioma, malignant gastrointestinal stromal tumor (GIST), squamous cell carcinoma (SCC), solitary fibrous tumor (SFT), and pleomorphic sarcoma (PS) was seen. One case of meningeal melanocytoma (Mme) and primary pleural liposarcoma (PL) involved the posterior mediastinum. Persistent disease was seen in LCH after 2 years. Of all the cases with malignant lesions, only the patient with SCC was alive after 1 year.
  
  
  CONCLUSIONS
  The cases of primary and SCC, LCH, melanocytoma, liposarcoma and PS, and GIST are unexpected and very rarely have paradigms in the mediastinum. Radiologic impression and knowledge of the compartment where these lesions arose from hardly assisted in arriving at a definitive opinion as the lesions were not typical of this location. A high index of suspicion and the immunohistochemical profile facilitated the final diagnosis.
authors.affiliation: Department of Pathology, Malabar Medical College and Research Center, Kozhikode, Kerala, India.
authors.forename: Fatima
authors.initials: F
authors.lastname: Shamsuddin
authors.affiliation: Department of Pathology, Kasturba Medical College, Mangalore, Karnataka, India.
authors.forename: Urmila N
authors.initials: UN
authors.lastname: Khadilkar
authors.affiliation: Department of Pathology, Kasturba Medical College, Mangalore, Karnataka, India.
authors.forename: Debarshi
authors.initials: D
authors.lastname: Saha
keywords: Langerhans cell histiocytosis; malignant gastrointestinal stromal tumor; mediastinum; meningeal melanocytoma; solitary fibrous tumor