Invasive Paget disease of the breast: two unique cases with diagnostic conundrum

Abstract

Abstract Introduction/Objective Invasive Paget disease of the breast is a rare entity with diagnostic challenges. It has been reported in 4-8% of cases of mammary Paget disease, while Paget disease itself represents only 1-4% of all breast carcinomas. The pigmented variant of this entity brings even greater diagnostic challenge. Herein, we present two patients with Paget disease of the breast with dermal invasion, one case with associated ulceration and another with pigmentation. Methods/Case Report Patient 1 is a 47-year-old female with a 9 mm right breast mass with a lobulated margins and calcifications. Simple mastectomy was grossly notable for nipple ulceration. Patient 2 is a 54-year-old female with a cm irregular mass in the right breast. Grossly, the nipple appeared blackened and mildly everted. Results (if a Case Study enter NA) Histopathologic evaluation of the nipple sections from patient 1 show invasive Paget disease with associated ulceration, with a depth of invasion of 4.5 mm. The breast biomarkers on the nipple section show tumor cells are negative for ER (0%) and PR (0%), and positive for HER2/neu (3+). Additionally, there was a separate 1.5 cm invasive ductal carcinoma, combined Nottingham histologic grade 3, pathologic stage of pT1c. The nipple sections from patient 2 show pigmented, invasive Paget disease, with a 1.5 mm depth of invasion. The tumor cells are positive for CK7 (weak), ER and PR, and negative for HER2/neu (1+). HMB45 and MART1 show increased reactivity in melanocytes. She also had a separate 2.5 cm invasive ductal carcinoma, combined Nottingham histologic grade 3, pathologic stage of pT2. Conclusion We present two unique cases of breast invasive Paget disease: one with associated ulceration, which brings challenges with tumor staging; and another one with pigmentation, which can be mistaken as melanoma. Invasive Paget disease must be distinguished from locally advanced breast cancer presenting as satellite skin nodules or skin ulceration, as it can lead to erroneous tumor over-staging as pT4b. It is important to recognize these two variations of invasive Paget disease so as to avoid over-staging or misdiagnosis, respectively, and to be cognizant of the fact that the treatment and prognosis differ.