A case of extensive ductal carcinoma in situ and sclerosing adenosis with metastasis on sentinel lymph node

Introduction: Sclerosing adenosis is a form of adenosis characterized by lobulocentric architecture, glandular and stromal proliferation in which the stromal component compresses and distorts the glandular structures. Atypical epithelial proliferations such as atypical lobular hyperplasia, lobular carcinoma in situ, and ductal carcinoma in situ may accompany areas of sclerosing adenosis. We present a case of ductal carcinoma in situ and sclerosing adenosis with metastatic carcinoma on sentinel lymph node. Case description: A 40-year-old woman presented with a palpable mass in her left breast. Radiologic studies showed a lesion suggesting malignancy in the left breast and atypical lymph node in the left axillary region. Left lumpectomy and sentinel lymph node biopsy was performed. Histopathologic examination revealed lobulocentric lesions with glandular proliferation and hyalinizing stroma in between. Foci of high-grade cribriform and solid type ductal carcinoma in situ were observed. Sentinel lymph node biopsy showed micrometastasis in one lymph node section. Based on these findings, the patient was diagnosed with high-grade ductal carcinoma in situ with sclerosing adenosis. However, the presence of micrometastasis in the lymph node suggested occult invasion that we were not able to detect. Conclusion: Ductal carcinoma in situ with sclerosing adenosis can mimic invasive carcinoma both radiologically and histologically. It should be kept in mind that there may be occult invasive carcinoma in patients with ductal carcinoma in situ whether the lesion is accompanied by sclerosing adenosis or not. Multiple sections and immunohistochemical studies can be of help.