Primary pulmonary pleomorphic adenoma. An immunohistochemical study and review of the literature.

Primary pleomorphic adenoma of the lung is an uncommon condition. We present a case of primary pulmonary pleomorphic adenoma and its immunohistologic features. The presence of immunoreactivity to both anticytokeratin and antivimentin antibodies for its epithelial components is suggestive of a primary pulmonary lesion. Its high proliferation index and its immunoreactivity to tumor regulatory gene p16(INK4A) are features that, to our knowledge, have not been reported previously. They may have a role in the frequent recurrence of these tumors many years after their apparently complete excision. Detailed genetic investigation and long-term follow-up of this rare tumor will aid in the characterization of its biologic profile.