A 15-month-old boy presented with bilateral breast enlargement and intermittent bloody nipple discharge since 4 weeks. On clinical examination, tenderness was present. Routine investigations (CBC and coagulation profile) and serum hormones (prolactin, TSH, estradiol, testosterone) were within normal range. Discharge cytology was negative for inflammatory cells. After conservative treatment of 2 weeks amount of bloody discharge reduced and resolved completely after one month.
Ultrasound examination was done with linear probe, which showed bilateral well-circumscribed, relatively symmetrical, complex cystic lesions showing internal complete echogenic septations with echoes/debris in few of the locules. On colour doppler, few of the septa shows vascularity. No significant surrounding fat stranding seen. There was no suspicious axillary lymphadenopathy.
Mammary ductal ectasia is a rare, self-limited, benign disorder occurring in infancy and childhood characterized by dilatation of the ducts with inflammation and fibrosis mainly in retroareolar area, although peripheral ducts may be affected in some cases . Milky discharge in newborn breast is a physiological finding for up to a week under the influence of maternal hormones. Bloody nipple discharge is rare in children and differential diagnoses include mammary duct ectasia, intraductal papilloma, intraductal cysts, mammary ductal hyperplasia and gynecomastia with mammary duct ectasia being the most common [2,3,4] . Incidence of ductal ectasia is higher in males as compared to females with M:F ratio 10:4 and usually it presents within age range of 2 months to 13 years. Etiology of duct ectasia is linked to placental-transmitted maternal and fetal hormones but later some reports suggested that it may be due to some developmental abnormality of childhood .
The most common symptom of duct ectasia is bloody nipple discharge but in advanced cases, it may present as palpable mass with tenderness . In our case, infant presented with bilateral breast swelling with tenderness. It may present as unilateral or bilateral involvement. Bilateral involvement is suggestive of the benign nature of disease therefore, bilateral involvement can be a useful finding in the diagnosis of mammary duct ectasia in pediatric patients who present with bloody nipple discharge, regardless of complex imaging findings.
Ultrasound is an important imaging modality inpatient with bloody discharge or breast enlargement. Most common ultrasound findings include dilatation of ducts in the form of an anechoic cystic lesion with or without echogenic material. Cystic lesions may be a simple cyst or a complex cyst having septation. Differential diagnosis of ductal ectasia is infantile gynecomastia, latter occurs in neonates due to exposure to maternal hormones and resolves within 2 years. USG findings in gynecomastia is a hypoechoic mass with spiculations or dendritic projections in the subareolar region. The major differentiating feature between the two is the age of onset and imaging findings of typical dilated ducts or cystic lesions in ductal ectasia.[8,9]
Although in adults, bloody nipple discharge has an increased risk of malignancy in infants and children it is a benign condition and the most common diagnosis with this symptom is duct ectasia which usually resolves spontaneously within 1 -9 months  . Treatment of ductal ectasia is reassurance and watchful ultrasound follow up. If any child presents with bilateral breast involvement with a complaint of bloody nipple discharge or swelling, we should always consider ductal ectasia as first diagnosis.
Take home message/Teaching points
Mammary ductal ectasia is a benign finding, so biopsy and surgical interventions should be avoided because such procedures may cause a permanent deformity in the breast thus careful observation using follow-up with USG is recommended.
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