Resumen: Bloody discharge from the nipple (thelorrhagia) is a rare symptom in childhood and is a cause of great concern due to the association with carcinoma in adults. The most common cause in children is mammary duct ectasia, which is a benign and self-limiting condition. It is characterized by dilatation of the mammary ducts, fibrosis and periductal inflammation. The etiology has not been identified and is multifactorial. Up to date, only isolated case reports have been published. Therefore, we present a review of the literature and we report a case of a fivemonth- old male infant that resolves spontaneously. We aimed to improve physicians'' diagnosis accuracy, the knowledge of this condition and to avoid aggressive studies and treatments. Idioma: Español DOI: 10.5546/aap.2018.e782 Año: 2018 Publicado en: Archivos Argentinos de Pediatria 116, 6 (2018), e782-e784 ISSN: 0325-0075 Factor impacto JCR: 0.506 (2018) Categ. JCR: PEDIATRICS rank: 118 / 124 = 0.952 (2018) - Q4 - T3 Factor impacto SCIMAGO: 0.219 - Pediatrics, Perinatology and Child Health (Q3)