Introduction: Intracystic (encysted) papillary cancer (IPC) is a rare entity of breast cancer accounting for approximately (1–2%) of all breast tumours , usually presenting in postmenopausal women and having an elusive natural history. The prediction of the biological behaviour of this rare form of breast cancer and the clinical outcome showed its overall favourable prognosis; however, its consideration as a form of ductal carcinoma in situ with non-invasive nature is to be reconsidered as it has been shown to present histologically with invasion of basement membrane and even metastasis . The objective of this review is to shed some light on this rare, diagnostically challenging form of breast cancer, including its radiological, histological, and molecular characteristics and its pathological classification. The final goal is to optimize the clinical management including the role of sentinel lymph node biopsy (SLNB), general management with adjuvant radiotherapy (RT), mammary ductoscopy, and hormonal treatment.
Methods: A literature review, facilitated by Medline, PubMed, and the Cochrane database, was carried out using the terms ‘Intracystic (encysted) papillary breast cancer’.
Results: Intracystic papillary breast cancer (IPC) is best managed in the context of a multidisciplinary team. Surgical excision of the lump with margins in excess of 2 mm is considered satisfactory. Sentinel lymph node biopsy (SLNB) is recommended as data have shown the possibility of the presence of invasive cancer in the final histology. RT following IPC alone is of uncertain significance as this form of cancer is usually low grade and rarely recurs. However, if it is associated with DCIS or invasive cancer and found in young women, radiotherapy may be prudent to reduce local recurrence. Large tumours, centrally located or in cases where breast conserving surgery is unable to achieve a favourable aesthetic result, a skin sparing mastectomy with the opportunity for immediate reconstruction can be offered. Adjuvant endocrine therapy may be suggested as almost certainly these tumours are hormonal positive.
Conclusion: Further research is required to determine the role of adjuvant radiotherapy and endocrine therapy in IPC. Understanding the low-grade nature of this form of breast cancer allows treatment options to be less radical and safely omitted.