We examined 32 cases (38 lesions) of extramammary Paget's disease (EMPD) in relation to comparative studies on intraductal carcinoma of the breast (ductal carcinoma in situ, DCIS) and apocrine adenocarcinoma (AAC). Lesions included scrotum (18 lesions), vulva (8), axilla (6), groin (3), penis (2) and chest wall (1), and the distribution was compatible with that of apocrine or supernumerary mammary glands. Histologically, extra‐mammary Paget's and DCIS cells exhibited a large amount of a pale‐stained cytoplasm. The cytoplasm of AAC cells frequently contained granules, was eosinophilic and differed from that of Paget's or DCIS cells. Immunohistochemical studies revealed positive reactions for polyclonal and monoclonal antibodies to carcinoembryonic antigen in all EMPD and most DCIS, but not in AAC. Recent studies have shown that extramammary Paget's cells exhibit characteristics of glandular epithelial cells and that most cases of EMPD are not accompanied by an underlying carcinoma. The results obtained in this study, coupled with data on the frequency of the supernumerary breasts, lead to the speculation that extramammary Paget's cells originate from ectopic mammary glands or from pluripotential germinative cells in the epidermis, capable of differentiating toward the mammary glands.

In cervical SCC, a grading system for lymphatic invasion according to D2-40 immunostaining is useful for the prediction of nodal metastasis and grade 2 lymphatic invasion is a strong predictor of nodal metastasis.

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Using immunohistochemical methods, we investigated the distribution of epithelial membrane antigen (EMA) on the normal eccrine gland, eccrine poroma and hidroacanthoma simplex. Granular membrane-associated reaction of EMA was detected on the outer cells of both the intraepidermal and the upper portion of intradermal eccrine ducts, as well as on the luminal surfaces and intercellular canaliculi of eccrine glands. Clear immunolabeling was also present in the tumor cells of eccrine poroma and hidroacanthoma simplex. Thus it is suggested that the constituent cells of these tumors originate from the outer cells of the intraepidermal and/or the upper portion of the intradermal eccrine ducts. There was no immunolabeling for EMA on the tumor cells of seborrheic keratosis and basal cell carcinoma. Immunohistochemical staining for EMA is a useful tool for the diagnosis of skin appendage tumors.

Immunohistochemical and immunoelectron microscopy studies revealed the presence of alpha-smooth muscle (alpha-SM) actin in fibroblasts located in the connective tissue sheath (CTS) of human anagen hair follicles. Immunostaining was positive from the base of the bulb to the upper part of the lower portion of the mature anagen hair follicles. The late catagen hair follicles did not stain. Ultrastructurally, alpha-SM actin was detected only in the fibroblasts located in the innermost layer of the transverse collagenous fibres. Since alpha-SM actin is located in cells with contractile potential, this newly identified layer may play an important role in the morphological changes of the lower portion of the hair follicle during the hair growth cycle.