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Background: The WHO has recognized a variant of pituitary adenomas with potential aggressive behaviour
which have been termed atypical pituitary adenomas. This group of tumours are recognized by
their mitotic rate of more than >3%, p53 expression and invasion of surrounding structures. There has
however been no study of the occurrence of these tumours in a black African population. This study is
a preliminary attempt to examine this group of tumours in blacks.
Methods: This study retrospectively reviewed fifty-seven histologically diagnosed and immunohistochemically
characterized pituitary adenomas received in our department over a twenty-one year period.
Specimens were stained with ki67, a nuclear marker of cell proliferation which has been identified as the
single best predictor of atypical pituitary adenoma.
Results: Twelve of the tumours showed atypical features with eight (67%) of these tumours being prolactinomas.
Two of the tumours were gonadotrophs and two were null cell adenomas. There was no correlation
with age or gender. Two of the tumours required neurosurgical re-exploration with one of these
showing a higher mitotic index in the second biopsy.
Conclusion: The study suggests similarity in the rate of occurrence of pituitary adenomas with atypical
features in a black African population with what is seen in Caucasians. Prolactinomas constitute a significant
percentage of the tumours with this feature.
2016 Alexandria University Faculty of Medicine. Production and hosting by Elsevier B.V. This is an open
access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).