Two cases of intracranial germinoma showing a cell arrangement mimicking carcinoma

Tumors of germ cell origin uncommonly arise in extragonadal sites. We report two cases of intracranial germinoma, in which it was necessary to distinguish between intracranial germinoma and metastatic carcinoma in cytological specimens. Cytologically, not only single tumor cells or loosely connective tumor cells but also closely packed clusters of cells and pair cells were recognized. Immunocytochemically, almost all tumor cells were immunoreactive for M2A, placental alkaline phosphatase, and c-kit. Closely packed clusters were also immunoreactive for pan-cytokeratin. Therefore, Cytopathologists should be aware that tumor cell clusters, mimicking carcinoma might appear in cytological specimens of intracranial germinomas. Although immunocytochemical analysis assists in correct diagnosis, some cell clusters showing cytokeratin immunoreactivity does not become the basis for the diagnosis of metastatic carcinoma. A panel of antibodies including D2-40, PLAP, and c-kit should be used.

Intrahepatic status of regulatory T cells in autoimmune liver diseases and chronic viral hepatitis

AIM

Regulatory T cells (Tregs) maintain immunological tolerance and suppress autoreactive immune responses. We evaluated the intrahepatic status of Tregs in patients with autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC), chronic hepatitis C (CH-C), or chronic hepatitis B (CH-B).

METHODS

We analyzed 85 patients (20 AIH, 22 PBC, 27 CH-C, and 16 CH-B) and 14 controls. Using liver tissue samples obtained by needle biopsy or from marginal parts of resected metastatic liver tumors in the controls, immunohistochemical analyses of forkhead box P3(+), which is a specific marker for Tregs, CD4(+), and CD8(+) cells were performed.

RESULTS

Intrahepatic Tregs were significantly more infiltrated in patients with liver diseases than in the controls. There were significantly fewer intrahepatic Tregs in the AIH patients than in the PBC patients (P = 0.037). Patients with alow frequency of intrahepatic Tregs were detected significantly more in the AIH and CH-B groups than in the PBC and CH-C groups (P < 0.05). In addition, the frequency of Tregs decreased in the liver of PBC patients as the pathological stage of the disease advanced. We found significantly less infiltration of CD4(+) T cells in AIH than in other diseases (P < 0.05). Liver-infiltrating CD8(+) T cells were detected more frequently in the CH-B group than in other groups (P < 0.003).

CONCLUSION

Intrahepatic Tregs were increased in both patients with autoimmune liver diseases and those with viral hepatitis. In autoimmune liver diseases, intrahepatic Tregs were fewer in the AIH patients than in the PBC patients.

Cellular localization of prolactin-releasing peptide receptors in the human pituitary

The recently identified prolactin (PRL)-releasing peptide (PrRP) is the first hypothalamic peptide hormone found to operate as a ligand of an orphan receptor that specifically stimulates PRL production from the pituitary gland. However, its other biological functions remain unknown. Using immunohistochemistry, we examined the distribution of the PrRP receptor in various human tissues, as well as the precise localization of the PrRP receptor in the human normal pituitary. Among various tissues examined, PrRP receptor-immunopositive cells were detected only in the pituitary gland. A double immunohistochemical procedure was used to examine PrRP receptor-positive cells from ten normal human pituitary glands, and it was determined that numerous PrRP receptor-positive cells are also positive for adrenocorticotropic hormone (ACTH) but negative for PRL. Growth hormone-, beta-thyroid-stimulating hormone-, beta-follicle-stimulating hormone-, beta-luteinizing hormone- or alpha-subunit-positive cells did not test positive for the presence of PrRP receptors. Thus, we suggest that PrRP receptor and probably PrRP may play a regulatory role in ACTH secretion, rather than in the release of PRL from the human anterior pituitary. This is the first report to demonstrate colocalization of the PrRP receptor and ACTH by immunohistochemistry.