Null cell adenoma

The tumors are positive for synaptophysin, chromogranin, and neuron-specific enolase and may express a variety of hormones (growth hormone, prolactin, TSH, ACTH, and FSH). A few are hormone negative and are designated as null-cell adenomas. Almost all are positive for CAM 5.2, either focally or diffusely, and about half are positive for AE 1/3. They are negative for cytokeratin 7, 19, and 20, as well as S-100 protein. Pituitary transcription factor-1 is selectively expressed in tumors that express growth hormone, prolactin, and TSH. No diagnostic molecular markers are currently in use for sporadic pituitary lesions. ... 

Null cell adenoma 12.4 Usually negative for hormones, but some cases are positive for p-FSH and a-su SF-1... 

From a pathological perspective, the detailed MS study of pituitary tumors can be used to determine whether proteins that regulate cell growth or hormone secretion are over- or under-expressed in neoplastic tissue, and whether they can be used as blood biomarkers of tumor mass and activity. For example, secreta-gogin, which is important for pancreatic 8-cell insulin secretion, is a newly discovered protein in the normal adenohypophysis it and its mRNA are underexpressed in null cell/gonadotroph pituitary adenomas [17]. Further studies are needed to determine whether secretagogin plays a physiological role in pituitary hormone secretion. 

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