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Presented by Theresa Chan, M.D. and prepared by Lynette S. Nichols, M.D.
Case 5: 54-year-old male with a headache.
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Question 1 of 1
1. Question
Week 123: Case 5
54-year-old male with a headache./images/Lyn’s/chan-4a.jpg
/images/Lyn’s/chan-4b.jpg
/images/Lyn’s/chan-4c.jpgCorrect
Answer: Pituitary adenoma
Histology: The tumor consists of a monomorphic population of cells with round nuclei and small nucleoli. The polygonal cells are arranged in sheets or cords. There is little supporting connective tissue or reticulin. In some areas in this tumor, the tumor cells appear plasmacytoid.
Discussion: Pituitary adenomas can show various architectural growth patterns, including diffuse or solid, sinusoidal or trabecular, papillary and glandular. The adenoma is not encapsulated and does not show the reticulin network seen in normal pituitary tissue. The tumor cells are usually round or polygonal, but occasionally may be elongated. The cytoplasm of the cells can be clear, basophilic or eosinophilic. The cells may also show a plasmacytoid appearance. When pituitary adenomas show plasmacytoid cells, it should be differentiated from a plasmacytoma. Immunohistochemical stains for neuroendocrine markers, cytokeratin and CD138 can readily distinguish the two lesions. A pituitary adenoma can be misinterpreted as an ependymoma, particularly when it shows papillary architecture. Immunohistochemical stains can be performed to distinguish the two lesions. Ependymomas are GFAP positive. In contrast, pituitary adenomas are GFAP negative. In contrast to most metastatic carcinomas, pituitary adenomas are positive for neuroendocrine markers, such as chromogranin and synaptophysin.
Incorrect
Answer: Pituitary adenoma
Histology: The tumor consists of a monomorphic population of cells with round nuclei and small nucleoli. The polygonal cells are arranged in sheets or cords. There is little supporting connective tissue or reticulin. In some areas in this tumor, the tumor cells appear plasmacytoid.
Discussion: Pituitary adenomas can show various architectural growth patterns, including diffuse or solid, sinusoidal or trabecular, papillary and glandular. The adenoma is not encapsulated and does not show the reticulin network seen in normal pituitary tissue. The tumor cells are usually round or polygonal, but occasionally may be elongated. The cytoplasm of the cells can be clear, basophilic or eosinophilic. The cells may also show a plasmacytoid appearance. When pituitary adenomas show plasmacytoid cells, it should be differentiated from a plasmacytoma. Immunohistochemical stains for neuroendocrine markers, cytokeratin and CD138 can readily distinguish the two lesions. A pituitary adenoma can be misinterpreted as an ependymoma, particularly when it shows papillary architecture. Immunohistochemical stains can be performed to distinguish the two lesions. Ependymomas are GFAP positive. In contrast, pituitary adenomas are GFAP negative. In contrast to most metastatic carcinomas, pituitary adenomas are positive for neuroendocrine markers, such as chromogranin and synaptophysin.
