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Morphological spectrum of mediastinal lesions with special emphasis on evaluation of needle biopsy: An experience from a tertiary care hospital

Background & objectives: Mediastinal lesions are uncommon and are infrequently encountered in routine clinical practice. Hence, there is a need for more elaborate studies of mediastinal lesions to make the pathologists and clinicians aware of the large spectrum of these lesions. The present study describes the histomorphological spectrum of various mediastinal lesions in a tertiary care hospital in India, along with the discussion of some unusual and interesting cases. Considering the limited diagnostic material obtained in guided biopsies, the adequacy of such tissue for providing a definite opinion was also evaluated. Methods: This was a retrospective study performed on 125 mediastinal masses diagnosed on surgically resected specimens as well as needle biopsies over a period of two years (January 2012-December 2013). A few cases had inadequate diagnostic material, making a total of 116 cases which were further evaluated. Results: A total of 116 patients of mediastinal lesions were included in the study. Most of the lesions were in 21-30 yr age group, with male:female ratio of 1.7:1. Anterior mediastinal compartment was most commonly involved. Majority of the cases (62.1%) were of neoplastic nature, with benign tumours (34.5%) being more common than malignant ones (27.6%). Thymoma followed by lymphoma constituted the most common mediastinal tumours. One-third of the total cases were diagnosed on needle biopsy samples. All cases where needle biopsy was followed by resection specimen showed concordant diagnosis. The percentage adequacy of biopsy was 91.7 per cent and the diagnostic accuracy was 100 per cent. Interpretation & conclusions: This study provides the histomorphological spectrum and biological diversity of the mediastinal lesions. It also emphasizes that biopsy is sufficiently adequate, with the help of a comprehensive immunohistochemistry panel, for providing a definite diagnosis in majority of cases.