Table 2.

Histopathologic characterization of selected mediastinal neoplasms.

Primary Diagnosis	n (%)	Reclassified as NMC n (%)
Total	114 (100)	4 (3.5)
Carcinoma †	84 (74)	1 (1)
Thymic Carcinoma	24 (21)	0
Poorly Differentiated/Undifferentiated Carcinoma	22 (19)	0
Squamous Cell Carcinoma	13 (11)	1 (8)
Non-small Cell Carcinoma	12 (11)	0
Poorly Differentiated Neuroendocrine Carcinoma	8 (7)	0
Sarcomatoid Carcinoma	2 (2)	0
Carcinoma, possibly thymic	3 (3)	0
Undifferentiated tumors #	30 (26)	3 (10)
Undifferentiated Malignant Epithelioid or Spindle Cell Neoplasm	24 (21)	2 (8)
Unclassified Round Cell Sarcoma	3 (3)	1 (33)
Undifferentiated Neoplasm	2 (2)	0
Atypical Epithelioid Neoplasm	1 (<1)	0

^†Cases which exhibited keratin immunoreactivity or otherwise met standard histopathologic criteria for diagnosis of carcinoma.

^#Cases without diagnostic histopathologic features or immunohistochemical staining patterns.