Null cell
adenomas and oncocytomas are clinically inactive
adenomas of the pituitary gland. They do not show any significant
hormone content detectable by immunohistochemistry. This study aimed at demonstrating mRNAs for all main
pituitary hormones in 32 null cell
adenomas and 31 oncocytomas by non-isotopic in situ hybridization using
digoxigenin-labeled
oligonucleotide probes. The results were compared with immunohistochemical and clinical data. Immunohistochemistry (ABC method) was done with
monoclonal antibodies against PRL, GH, FSH, LH, TSH,
ACTH, alpha-subunit, and Ki-67 (mib-1). The signals for
hormone production were detected in both
adenoma types in a range from 42% for GH in oncocytomas to 78% for beta-FSH in null cell
adenomas. However, these signals are apparently not effective on
hormone production, as was shown by almost negative immunostaining. Owing to the simultaneous detection of at least two mRNAs in 78% of null cell
adenomas and in 94% of oncocytomas, we assume that both
tumor types originate from pluripotential precursor cells that are capable of producing various
hormones. According to our data, it is unlikely that the signals influence the clinical behavior.