The distribution of carcinoembryonic antigen (CEA) and its relationship to calcitonin in early, localized, and disseminated (virulent) medullary thyroid carcinoma (MTC) have been studied using immunoperoxidase methods. Carcinoembryonic antigen can be demonstrated within C‐cells through all stages of progression of MTC. In early disease (C‐cell hyperplasia and microscopic carcinoma), CEA, and calcitonin have a similar distribution, being present in virtually every cell. Likewise, calcitonin and CEA have a similar, homogeneous distribution among cells in gross medullary carcinoma confined to the thyroid region. In both primary and metastatic tumors from patients with virulent, disseminated disease there is an inverse relationship between calcitonin and CEA distribution such that CEA expression is retained and frequently present in the greatest amounts in cells which have poor or absent staining for calcitonin, and present in the least amounts where cellular staining for calcitonin is greatest. It is postulated that in MTC expression of CEA (a marker for early epithelial differentiation), in the face of loss of calcitonin (a marker for terminal differentiation/cellular maturity), may reflect a degree of maturation block in tumors from patients with aggressive disease.
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.
Adenoid cystic carcinoma of the breast is a rare neoplasm, with only 140 cases having been reported to date. Data on 123 of these cases are reviewed herein and another case is presented in detail. Several features distinguish this type of breast cancer from more typical histologic types and suggest that it may have a unique tumor behavior. The prognosis appears to be favorable and the incidence of axillary lymph node involvement is lower. Distant metastases are uncommon, but they tend to occur without prior lymph node involvement. This lack of prognostic significance for negative axillary lymph nodes underscores the need for other prognostic markers in this disease and suggests that axillary dissection can be eliminated in most cases. Similarities to typical breast cancer include the incidence of local recurrence and the lack of effect of surgical treatment on distant metastases and overall survival. These data suggest that breast-conserving treatment may be applicable to adenoid cystic carcinoma.
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