A plurihormonal TSH-producing pituitary tumor of monoclonal origin in a patient with hypothyroidism.

Objective: A clinicopathological and clonal study of a pituitary tumor was made in a 26-year-old woman with chronic thyroiditis to differentiate TSH-producing adenoma from TSH hyperplasia.
Methods: Tumor specimens were subjected to histopathological study and clonal analysis (HUMARA).
Results: Immunohistochemical examination disclosed TSH-beta, PRL, GH, ACTH, FSH-beta, LH-beta, and alpha-subunit production in the adenoma cells. These heterogeneous phenotypes are characteristic of both thyrotroph hyperplasia and plurihormonal TSH-producing adenoma. However, the HUMARA method demonstrated monoclonality of the tumor cells.
Conclusion: Monoclonality of the tumor cells proved that the pituitary tumor was plurihormonal TSH-producing adenoma, not TSH hyperplasia.
(Copyright 2003 S. Karger AG, Basel)