Gestational trophoblastic neoplasms: Morphologic correlates of therapeutic response

GTN were evaluated histologically in reference to biologic behavior and response to chemotherapy. GTN requiring more intensive, multiple drug chemotherapy usually exhibited increased mitotic activity, nuclear atypias, compact growth of cytotrophoblast, and little maturation, as compared to lesions that responded more favorably. Fibrinoid at the interface of tumor and host tissues was associated with a favorable response to drug therapy. Patients requiring more intensive chemotherapy were more likely to present with distant metastases and high levels of hCG prior to treatment and to reach remission only after many courses of treatment. The clinical and morphologic features of fatal cases suggest that these represented the extreme of a biologic continuum, with collapse of defense mechanisms despite chemotherapy. The early recognition by the pathologist of those lesions that may be resistant to chemotherapy is important to the clinician in selection of an optimal treatment protocol.