Pulmonary Adenocarcinoma of Fetal Type: Report of a case

ABSTRACT

Pulmonary adenocarcinoma of fetal type is a very uncommon tumor of the lung which simulates an early stage of lung differentiation. This is a primitive appearing epithelial tumor similar to the epithelial component of pulmonary blastoma but lacking the sarcomatous features. Since the report of Kradin et al, 8 more cases have been reported by a variety of name. These tumors are composed of glycogen-rich, non-ciliated tubular epithelial cells forming irregularly shaped tubules or arranged in a papillary pattern. A very remarkable findings of this tumor is the presence of endocrine cells which is confirmed by argyrophilia, immunohistochemistry or electron microscopy. We experienced a case of this tumor which showed hepatocytoid differentiation in addition to the characteristic histologic findings. Immunohistochemical studies performed on a resected tumor tissue showed immunoreactivity for alpha-fetoprotein, neuron-specific enolase and somatostatin, and endocrine type granules were found ultrastructurally. Although this tumor seems to have a relation with pulmonary blastoma in its histology, immunohistochemistry and ontogeny, a distinction between these should be attained because the average survival of the former group is longer as 23 months, while that of the latter is only 4 months.