Periductal mastitis is a condition where lactiferous ducts in the breast are distended and filled with amorphous eosinophilic material and foam cells, with concomitant presence of severe periductal chronic inflammation. In the literature, it is also found under synonyms such as mastitis obliterans, plasma cell mastitis, or comedomastitis.
This condition is still often confused with mammary duct ectasia, but the latter is actually a separate condition that affects older women and is characterized by subareolar duct dilatation and less active periductal inflammation process.
Pathogenesis of the Disease
Current evidence points to smoking as the most important risk factor in the etiology of periductal mastitis. Approximately 90% of women who get this condition (or its complications) smoke cigarettes, in comparison to 38% of women of the same age group in general population.
It is thought that toxic substances in cigarette smoke directly or indirectly cause damage of the walls of subareolar breast ducts. This represents an ideal milieu for microorganisms that can multiply and cause an infection in such damaged tissues. It must be emphasized that the causative agents usually differ from those in lactational infections, with anaerobic bacteria playing a prominent role.
Nevertheless, the initial inflammation is chemical in origin. The damaged walls of ducts become permeable to the lipid and cellular contents that are normally contained within the lumen, which subsequently excite a chemical periductal inflammatory process characterized by plasma cells infiltration. Only after that a secondary infection can ensue if the condition does not resolve spontaneously within a week or two.
Initial presentation of periductal mastitis is often with periareolar inflammation (either with or without an associated mass), but abscess can also be already established. Associated symptoms include central noncyclical breast pain and purulent nipple discharge.
Moreover, acute episodes of the disease usually cause transient episodes of nipple retraction that resolve on its own as the inflammation abates. Nevertheless, acute forms of the disease can progress further to chronic periductal mastitis and, finally, to periductal fibrosis and permanent nipple retraction.
In approximately one out of five individuals with periductal mastitis, subareolar breast abscess occurs, which is an infectious, irreversible process. Purulent material usually drains spontaneously, while a recurrent periareolar fistula is seen as a complication in 20% of all cases.
Diagnosis and Management of Periductal Mastitis
Triple assessment is usually pursued in the diagnosis of periductal mastitis, which is an umbrella term that encompasses ultrasound examination (to differentiate inflammation from abscess formation), mammography (which reveals an opaque mass of ducts), and clinical examination that reveals skin indentation. Furthermore, microbiologic evaluations are pursued on any discharge or fluid aspirate.
A careful evaluation using ultrasound of the focal area of pain most often shows definitive evidence of periductal inflammation. Unfortunately, initial chemical periductal mastitis cannot be straightforwardly distinguished from the true infection, which is essential for subsequent therapeutic decisions.
Hence, the treatment of periductal mastitis is with appropriate antimicrobial therapy, albeit the infection is often recurrent because antibiotics do not remove the damaged subareolar ducts. If abscesses were formed, they are managed with aspiration or incision and drainage. Recurrent episodes of periareolar infection necessitate total duct excision.