An unusual case of carcinoma of the prostate with metastases is described. the prostate and the metastases showed adenocarcinoma with carcinoid-like areas. A tumor with the same histologic features was found at the tip of the appendix and proved to be metastatic. The possibility of primary carcinoid of the prostate was considered; however, Fontana-Masson stain and electron microscopy failed to confirm this. Immunoperoxidase stain for prostatic acid phosphatase was done on the prostate and metastases. This stain is specific for tissues of prostatic origin. The stain was positive in the carcinoid-like areas, indicating that it was not a true carcinoid but rather prostatic carcinoma with a carcinoid-like pattern. Apparently, this is the first case of a metastatic prostatic carcinoma showing carcinoid-like areas that were positive for prostatic acid phosphatase.
Observations of the ultrastructure of Charcot-Leyden crystals are sporadic in the literature. These crystals appear occasionally in clinical materials, however, and may pose diagnostic dilemmas if not correctly identified. Two cases in which unusual crystallike structures were seen on electron micrographs of specimens were evaluated for diagnostic purposes. These structures were tentatively identified as Charcot-Leyden crystals and subsequently were confirmed as such by immunoperoxidase labeling. The cases are reported together with a review of the ultrastructure, histology, immunology, and natural history of Charcot-Leyden crystals.
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