Tumors of Uncertain Histogenesis

This is a variable group of tumors for which a specific cell of origin is debatable. The tumors in this group do not share any histopathological characteristics. In general, this group of tumors occur rarely and their malignant potential is difficult to determine in a small biopsy. In some cases, the primary tumors are considered benign but may spread into lymph nodes. These tumors an occur in the periphery of the lung or in central location. Even though a small biopsy is obtained as a diagnostic procedure in the assessment of these tumors, more often than not, the final interpretation is only after complete surgical resection has been accomplished and after extensive immunohistochemical analysis has been performed. Diagnostic imaging is important in establishing whether the tumor is a solitary tumor mass; however, it is difficult to separate these tumors by those means, ultimately relying on surgical resection for definitive diagnosis. Immunohistochemical studies are important in the assessment of these tumors.