Abstract
Reported herein is a 25-year-old woman who was treated for a large and highly atypical prolactin-producing pituitary adenoma. On presentation, she exhibited right hemiparesis and left-sided visual loss, associated with amenorrhea. A massive (>5 cm) intra- and suprasellar lesion was seen on imaging, and her serum prolactin level was 4408 ng/ml. The patient received dopamine agonist treatment preoperatively for 4 weeks. To resect the tumor, a two-stage excision was required. Histologically, the specimen was composed of polygonal or spindle cells showing marked nuclear pleomorphism and/or multinucleation. Fibrosis was also focally conspicuous. Differential diagnoses included pituitary adenoma, pituitary carcinoma, pituicytoma, paraganglioma, spindle cell oncocytoma, and meningioma. Immunohistochemically, the tumor cells were positive for prolactin, chromogranin-A, and synaptophysin, but were negative for glial fibrillary acidic protein, S-100 protein, epithelial membrane antigen, and vimentin. No apparent cerebrospinal or systemic metastases are found. Ultimately, prolactin-producing pituitary adenoma was diagnosed. Our case highlights the difficulty in definitively diagnosing an unusual prolactin-producing adenoma based on histopathology alone and the importance of referring to clinical information and immunohistochemical findings when deriving the diagnosis.
Highlights
In tissue sections, prolactin (PRL)-producing pituitary adenomas typically present as monotonous arrays of chromophobic cells in diffuse, papillary, or sinusoidal proliferations
After short-term exposure to dopamine agonist (DA), apoptotic cells/bodies [2] and multinucleated giant cells may be present [3], but fibrous change is exceptional. In those instances where use of DA has altered tumor morphology, therapeutic efficacy is commonly signaled by tumor involution and/or decline in serum PRL level, plus diminished PRL immunoreactivity [4]
Conclusions we describe a patient who underwent treatment for a sizeable and visibly atypical prolactinoma
Summary
Prolactin (PRL)-producing pituitary adenomas typically present as monotonous arrays of chromophobic cells in diffuse, papillary, or sinusoidal proliferations. Such cells generally are of uniform size, lacking both nuclear atypia and mitotic figures. A massive (>5 cm) tumor of intra- and suprasellar location, excluding mesencephalon backward, was seen on computerized tomography (CT) of the head (Fig. 1a). The chromophobic nature of tumor cells was confirmed by Pearse’s Periodic Acid Schiff (PAS) stain (Fig. 3b). A final diagnosis of PRL-producing pituitary adenoma was reached after considering the immunohistochemical profile, suprasellar location, and prolactin production of the tumor, as well as the absence of metastatic foci and invasion into surrounding tissue
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