Bilateral Paget’s Disease of the Breast—Case Report of Long-Time Misdiagnosed Tumors with Underlying Ductal Carcinomas and Review of the Literature

Paget’s disease of the breast is often misdiagnosed. We report on a 72-year old patient with a history of 2.5 years without any malignant findings, followed by the identification of a bilateral Paget’s disease with bilateral breast cancers. This case underlines how important histological examinations even in unusual clinical pictures are. 1. Introduction Paget’s disease (PD) of the breast can be a diagnostic challenge. It might take years until the diagnosis. If the skin changes are intended to be benign but do not respond to topical therapy, a biopsy has to be performed to exclude malignancies. Almost all cases are single sided. We observed one of the rare cases of bilateral PD. 2. A Case Report A 72-year-old woman (para 1) was seen with erythematous and eczematous patches that developed simultaneously on both nipples and had been present for 2.5 years (Figures 1(a) and 1(d)). No individual or familiar risk factors were known. She was extensively evaluated by gynecology and several investigations were performed (mammography, vacuum-punch biopsies, and cytological examination of breast fluid), but only minor dysplastic changes were detected in the breast fluid cytology. The patient was then treated with topical antimycotics, antibiotics, and corticosteroids. Figure 1: Clinical picture at time of first presentation and histological stains ((a) right breast, (b) cytokeratin 7 stain, (c) HE stain, and (d) left breast). After 2.5 years she was referred to dermatology, where we biopsied both nipples. The histopathology showed epidermal cells with hyperchromatic and polymorphic nuclei, intraepithelial gland cells (Figure 1(b)), and a high expression of cytokeratin 7 (Figure 1(c)), so-called Paget’s cells. Cytokeratin 7 is a typical marker for glandular and transitional epithelia. Because of an induration of the left mamma and the incidence of underlying carcinomas, the patient was evaluated again by gynecologists who decided to operate on both breasts. They identified a bifocal invasive ductal carcinoma and an intermediate grade ductal carcinoma in situ (DCIS) of the left breast and a low-grade DCIS of the right central breast. Sentinel lymph nodes were not involved. Following surgery, the patient received chemotherapy with 6 cycles FEC (5-fluorouracil, epirubicin, and cyclophosphamide), trastuzumab, because of positive Her-2 status, radiotherapy, and tamoxifen. At 1.5-year follow-up being maintained on tamoxifen, she showed no relapse. 3. Discussion Between 1 and 4% of all breast cancers are Paget’s diseases [1]. Bilateral synchronous tumors occur in about