Imaging of Intracystic Papillary Carcinoma.

Objective: To describe the clinical, imaging, and histopathologic findings of intracystic papillary carcinoma (IPC) of the breast.
Materials and Methods: Following institutional review board approval, a database at a single institution was searched to identify cases of patients who received a diagnosis of IPC from 1999-2013 and who had undergone preoperative imaging with mammography, sonography, or MRI. The clinical, mammographic, sonographic, and MRI features of IPC were compared and analyzed using the BI-RADS mammography, ultrasound, and MRI lexicons.
Results: The study sample included 40 patients, 36 females and 4 males. The most common clinical presentation was a palpable mass. Mammographic data was assessed in 31 patients. A tumor was mammographically occult in one patient. The predominant features were oval shape of 17 tumors (57%), obscured margins of 12 (40%), and high density of 20 (67%). Ultrasound data of 37 patients revealed 20 oval masses, 13 irregular masses, and 4 round masses. Fourteen complex solid and cystic masses were identified. One patient underwent MRI that showed a complex, enhancing mass with washout kinetics. Ultrasound guided biopsy was performed on 33 of the 37 masses. Core needle biopsy and fine needle aspiration (FNA) biopsy were most commonly performed on the solid components of the complex solid and cystic masses. IPC was diagnosed by stereotactic biopsy in 1 patient with a suspicious mass on mammography with no correlate on sonography and 6 patients had surgical excision without imaging-guided biopsy. Pathology showed in situ IPC in 31/40 tumors and 11 were solid and cystic complex masses on ultrasound. Pathology revealed invasive IPC in 9 tumors and five had an irregular mass on ultrasound.
Conclusion: Our study reveals no specific imaging features to differentiate in situ vs invasive IPC. The most common ultrasound feature in biopsy proven IPC was an oval mass, however, we identified that a complex solid and cystic mass is more often associated with the diagnosis of in situ IPC and an irregular mass is more often associated with the diagnosis of invasive IPC. Future studies with larger cohorts are needed to further define the clinical and imaging features of this rare malignancy.
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