Background: Cystic hypersecretory duct carcinoma (CHC) of the breast, first described in 1984, is a rare variant of duct carcinoma. Histologically it is characterized by the formation of dilated ducts and cysts containing an eosinophilic secretory product resembling thyroid colloid. The lining epithelium of the cysts atypically proliferates to form intraductal carcinoma. Only four cases of invasive cystic hypersecretory carcinoma have been reported.
Case: We present a case of invasive CHC with tumor emboli in many lymphatic spaces and axillary nodal metastases. The lesion was also evaluated by fine needle aspiration. Direct smears with Papanicolaou stain were highly cellular and had abundant, intensely staining, orange-to-gray-green thyroid colloid-like material. Epithelial cells, showing a variety of cellular patterns, were indistinguishable from usual ductal carcinoma cells. These cytologic findings may be characteristic enough to suggest cystic hypersecretory carcinoma.
Conclusion: The cytologic features of CHC are distinctive and correlate with histology. This was the first presentation of colloidlike secretory material in cytologic material with Papanicolaou stain in such a case. Invasive CHC tends to have aggressive behavior. Cystic hypersecretory hyperplasia coexisted in this case.