Small cell carcinomas of the prostate are rare. A few reported cases have manifested morphologic and functional neuroendocrine characteristics, and it has been suggested that these tumors are derived from the argentaffinic/argyrophilic cells normally present in the prostate. The authors have recently studied three cases of primary prostatic small cell carcinoma in which the small cell component developed during the course of progression of “regular” prostatic adenocarcinoma, and reflected a terminal aggressive phase of the disease. Immunoperoxidase staining for prostate‐specific acid phosphatase (PSAP) showed positivity in the adenocarcinoma but absence in the small cell component of each tumor. The association of small cell carcinoma with prostatic adenocarcinoma indicates that in considering the histogenesis of prostatic small cell carcinoma, a specific neuroendocrine cell of origin need not be implicated.
Five cases of papillary adenocarcinomas of the prostate were studied for prostate‐specific acid phosphatase, using the immunoperoxidase method, to determine the origin and histogenesis of these uncommon tumors. All five cases were prostatic‐acid‐phosphatase positive, whereas four cases showed in situ carcinoma involving large periurethral ducts. Positive immunohistochemical localization of prostate‐specific acid phosphatase is useful in identifying papillary carcinoma of true prostatic origin and distinguishing them from prostatic‐acid‐phosphatase‐negative carcinomas which may include tumors arising from periurethral glands or metaplastic urethral mucosa.
Rheumatoid factor (RF), isolated from sera of patients with rheumatoid arthritis, attached to infectious vaccinia virus-IgG (Vac-IgG) complexes. Neutralization did not occur until the Vac-IgG-RF complexes were incubated with either goat antihuman IgM or complement. The amount of RF that attached was proportional to the concentration of IgG incubated with the virus. The enhancement by RF of complement-mediated neutralization of Vac-IgG was not dependent upon the order of addition of the immunoreactants. Complement addition before, with, or after RF resulted in the same amount of neutralization. These observations suggest that under certain conditions RF may play a role in the defense against viral infections.
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