An unusual case of mammary Paget’s disease in a woman with psoriasis.

Mammary Paget’s disease (MPD) is a malignant breast tumor, which is characterized by intraepidermal infiltration from malignant glandular epithelial cells. Often it may include an underlying ductal carcinoma in situ or an invasive ductal carcinoma. Clinically it appears as an erythematous patch, moist or crusted, with or without desquamation that in some cases becomes ulcerated, causing infiltration and inversion of the nipple. We report the clinical case of a 60-year-old woman, treated in our department for psoriasis, presenting with erythema of nipple and areola with nipple erosion, ulceration and poor secretion. Suspecting Paget’s disease of the nipple, radiological exams (mammography and breast MRI) were performed. A biopsy for histological examination was carried out and confirmed the diagnosis of mammary Paget’s disease. MPD is sometimes difficult to diagnose both clinically and radiologically, therefore it is important to distinguish from other conditions: in literature MPD is reported in differential diagnosis with psoriasis given its similar clinical features, and in some cases MPD has been treated with topical and systemic steroids due to a wrong diagnosis. However, the concomitance, in the same individual, of mammary Paget’s disease and psoriasis has never been described.