Pineal cell tumors

PINEAL CELL TUMOR OF INTERMEDIATE DIFFERENTIATION (LIKELY GRADE II OR III)... 

Primary pineal cell tumors are less differentiated than pineocytomas and more differentiated than pineoblasto-mas. They show mitotic activity and moderate crowding of their synaptophysin-positive cells. They may contain regions that resemble pineocytoma near regions like pineoblastoma. Their proliferation is regionally variable, with hot spots of proliferation higher than that of pineocytoma. 

Tumors described in this section arise from pineal cells or their precursors. Because tumors that arise from pineal cells are neurons, synaptophysin immunoreactivity is common. Some tumors also react for retinal-S antigen (Fig. 20.37). Many other tumors, including gliomas,... 

Within the cranial vault, 95% of primary germ cell tumors are found along the midline in the pineal and suprasellar regions, especially the former. About 10% involve both regions, and 25% arise in the suprasellar cistern. The mixed germ cell tumor and lymphoma (ger-lymphoma) has only been seen in the sella turcica. Germ cell tumors rarely involve spinal cord or peripheral nerve. ... 

Important characteristics of carcinoma as it relates to the CNS and meninges are its distinctively epithelial structure (Fig. 20.58A see Table 20.6) and the overwhelming predominance of metastatic over primary carcinomas. Metastatic carcinomas are described in detail in Chapter 8, Immunohistology of Metastatic Carcinomas of Unknown Primary. Rare primary brain carcinomas occur in the choroid plexus, from germ cell tumors of the pineal and suprasellar regions, and from cysts. 725 section emphasizes how to distinguish between carcinomas (see Fig. 20.58B to D) and various primary intracranial tumors (see Box 20.2). 

Thymic regrowth and reactivation of thymic endocrine activity may occur in older animals by different endocrinological or nutritional manipulations than in young animals. Intrathymic transplantation of pineal gland or treatment with melatonin, implantation of a growth hormone (GH) secreting tumor cell line or treatment with exogenous... 

Most primary tumors of the pineal gland originate from pineocytes, which represent modified neurons similar to retinal photoreceptor cells.Pineocytomas are typically positive for NSE, synaptophysin, neurofilament proteins, tan protein, and microtubule-associated protein-2 (MAP2) (Fig. 10.5). GFAP and S-100 protein are present in 75% and 83% of cases, respectively. 

FIGURE 20.38 Crowded malignant cells with pleomorphic and hyperchromatic nuclei in this pineal tumor express synaptophysin (A) but not GFAP (B) in serial sections of this pineoblastoma. 

Mena H, Rushing EJ, Ribas JL, et al. Tumors of pineal parenchymal cells A correlation of histological features, including nucleolar organizer regions, with survival in 35 cases. Hum Pathol. 1995 26 20-30. 

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