Risk factors for development of mammary duct fistula:
(1) periareolar abscess
(2) periductal mastitis with mammary duct ectasia
(3) previous breast surgery (typically a breast biopsy)
(4) spontaneous cutaneous or surgical drainage of an abscess
(5) congenital or acquired duct obstruction
(It would be interesting to note if infection with Staphylococcus aureus is a risk factor.)
Berna et al reported that some cases may not involve a cutaneous fistulas communicating with the lactiferous ducts but rather arise from follicular-sebaceous cysts that become infected.
The fistula tract and originating duct can be surgically excised with primary closure or left open to granulate. However, some patients may have a recurrence, especially if there is active infection. Appropriate antibiotic therapy after surgery may reduce the risk of recurrence.
Berna et al used a combination of microwave and ultrasound therapy to the fistula site for 3 weeks which resulted in resolution without requirement for surgery and low risk of recurrence. A second course of therapy with or without steroid injection was successful in resolving recurrences.
