Minimal deviation adenocarcinoma (adenoma malignum) of the endocervix: a histochemical and immunohistochemical study of two cases.

The histopathological diagnosis of minimal deviation adenocarcinoma (adenoma malignum) of the endocervix may be difficult. Two cases of minimal deviation adenocarcinoma (MDA) were examined using mucin histochemistry and immunocytochemistry with antibodies to epithelial membrane antigens (HMFG1, Ep1), low-molecular-weight cytokeratins (CAM 5.2), carcinoembryonic antigen (CEA), and alpha-amylase. The results were compared with those for normal endocervical glands. Reactivity for CEA in MDA was focal and would be unreliable for biopsy diagnosis. Both cases of MDA contained abundant neutral mucins and sialomucins, whereas sulfomucins were rarely detected; this pattern contrasted with that of normal endocervix. Neoplastic glandular epithelial cells in MDA consistently showed both luminal and cytoplasmic reactivity with Ep1 and HMFG1, whereas normal cervix showed luminal labeling only. Thus, mucin histochemistry and immunohistochemical detection of epithelial membrane antigens may distinguish between extremely well differentiated neoplastic glands in MDA and normal endocervical glands, and hence may aid diagnosis in biopsy specimens.