Interfollicular Hodgkin's lymphoma and Castleman's disease.

reactive follicular hyperplasia of the lymphoid tissue and an epithelial inclusion, located immediately beneath the nodal capsule (Figure 1a). The inclusion consisted mainly of aggregates of tubular glands of variable size, lined by luminal cuboidal cells and a distinct outer layer of clear cells, consistent with myoepithelial cells (Figure 1b). Some glands were lined by apocrine epithelium consisting of cuboidal cells with eosinophilic granular cytoplasm, round nuclei and prominent nucleoli. Rare glands were appreciably enlarged and their lumina appeared almost entirely filled with cells showing abundant cytoplasm with indistinct borders and round to ovoid nuclei with uniform cromatin and inconspicuous nucleoli (Figure 1c). No mitoses, necrosis or cells with atypical features were detected. Finally, small cystic structures lined by squamous epithelium were also present. Immunostaining for actin revealed an intact layer of myoepithelial cells around all the glandular structures (Figure 1d), but not in the wall of the squamous microcysts. On the basis of cytological and architectural criteria and the immunohistochemical highlighting of the myoepithelial cells, the present case was interpreted as a nodal inclusion of ectopic breast tissue with focal florid ductal hyperplasia. To the best of our knowledge, there are only a few reports of proliferative lesions in nodal breast tissue inclusions. In most cases the authors described apocrine metaplasia of breast epithelium and proliferative changes with features resembling florid adenosis and sclerosing adenosis. In one case the ectopic breast tissue had features of a benign papilloma. The only previously reported example of axillary ectopic breast tissue with features of ductal hyperplasia, similar to the present one, is the case described by Maiorano et al. In this report, the authors describe ectopic breast tissue, consisting of duct-like structures with foci of intraductal hyperplasia showing complete obliteration of the lumen and formation of pseudo-cribriform spaces, similar to florid duct hyperplasia commonly encountered in proliferative fibrocystic disease of the breast. These cases support the accumulating evidence that ectopic breast tissue can undergo proliferative intraductal changes and consequently it appears reasonable to speculate on the possibility of a primary breast carcinoma of the axillary nodes.