Abstract
Purpose and Methods Phenotype transformation in pituitary adenomas (PA)
is a little known and unexpected clinical phenomenon. We describe two
illustrative cases and performed a systematic review of cases reported in
literature.
Results
Case 1: A 24-year-old woman underwent surgery because of
Cushing’s disease. A complete tumor resection and hypercortisolism
resolution was achieved. Two years later, tumor recurred but clinical and
hormonal hypercortisolism were absent. Case 2: A 77-year-old woman
underwent surgery due to acromegaly. A complete tumor resection and GH excess
remission was achieved. Four years later, tumor recurred but clinical and
hormonal acromegaly was ruled out. Search of literature: From 20 patients
(including our cases), 75% were female with median age 45 (19) years.
Ten patients (50%) had initially functioning PA: 8 switched to NFPA (5
ACTH-secreting PA, 2 prolactinomas and 1 acromegaly) and 2 exchanged to
acromegaly from TSH-secreting PA and microprolactinoma. One patient developed a
pituitary carcinoma from ACTH-secreting PA. Ten patients (50%) initially
had NFPA; 9 developed Cushing’s disease (4 silent corticotroph adenomas,
4 null cell PA and 1 managed conservatively). One patient with silent
somatotroph PA changed to acromegaly. Treatments before transformation were
surgery (80%), radiotherapy (40%), pharmacological (40%)
and in 2 patients switching happened without any treatment. Median follow-up
until transformation was 72 months (range 12–276).
Conclusion PA can change from functioning to (NF) non-functioning (vice
versa) and even exchange their hormonal expression. Clinicians should be aware
and a careful lifelong follow-up is mandatory to detect it.
Key words
pituitary adenoma with switching phenotypes - pituitary adenoma transformation - pituitary
adenoma metamorphosis
