Diagnosis of Intracystic Papillary Carcinoma of the Breast by Preoperative Core Needle Biopsy: A Case Report

Abstract

Intracystic papillary carcinoma (ICPC) of the breast is rare. It is categorized as noninfiltrating papillary ductal carcinoma in situ (DCIS). It protrudes and grows into the inner cavity in a papillary form, usually unaccompanied by severe infiltration in the surrounding interstitium. ICPC is often a noninfiltrating carcinoma and differentiating it from benign intracystic papilloma is difficult using preoperative imaging alone. Therefore, deciding on a treatment policy is often difficult. For correct diagnosis, it is vital to perform fine needle aspiration (FNA) or core needle biopsy (CNB) of the intracystic solid part accurately and under ultrasound guidance. However, the rate of accurate diagnosis by FNA cytology is low, and diagnosis by CNB is reported to be more effective than cytology. CNB of the solid part of a cyst for preoperative diagnosis is difficult and has a sensitivity of 60%. There is also a report stating that preoperative diagnosis could not be obtained in 40% of patients with ICPC. Therefore, biopsy by resection should be considered in patients who cannot be diagnosed by either FNA or CNB. However, DCIS had better be preoperatively diagnosed because not only axillary lymph node dissection but also sentinel lymph node biopsy might be omitted. The patient was a 42-year-old woman. She found a tumor mass in the left inner breast 10 weeks before her initial visit to the author's clinic. It was difficult to differentiate between the benignity or malignancy of the tumor from images, but a diagnosis of ICPC was made using preoperative CNB.