Amphicrine differentiation in bronchioloalveolar cell carcinoma

We report for the first time a classical bronchioloalveolar cell carcinoma with both exocrine and endocrine differentiation (amphicrine) in the same cell. At electron microscopy the tumor cells showed a mixed type II alveolar cell/Clara cell and mucous differentiation. In addition, there were many dense-core neurosecretory granules at the base of the majority of the cells. Immunocytochemically the tumor showed positivity for surfactant and a panel of neuroendocrine antibodies, including NSE, PGP9.5, synaptophysin, and chromogranin A. The presence of neuroendocrine differentiation was not hinted at by routine histology and did not indicate a more aggressive behavior in this case since the patient is well 3 years after the resection.