Squamous Metaplasia of Lactiferous Ducts



Squamous Metaplasia of Lactiferous Ducts












The normal keratinizing surface epithelium normally dips into the nipple orifice for only 2-3 mm image. If keratin production occurs deeper in the duct image, the keratin is trapped and causes distension of the duct. If rupture occurs, an intense foreign body inflammatory response to the keratin ensues image. The patient develops an erythematous painful subareolar mass, often mistaken for a bacterial infection. Incision and drainage procedure does not remove the pathologic lesion, and recurrences are common. The path of least resistance is beneath the smooth muscle of the nipple. Patients may develop a fistula track opening at the edge of the areola image. Definitive surgery removes the offending duct.


TERMINOLOGY


Abbreviations



  • Squamous metaplasia of lactiferous ducts (SMOLD)


Synonyms



  • Recurrent subareolar abscess


  • Zuska disease


  • Periductal mastitis


Definitions



  • Abnormal keratin formation in lactiferous sinuses leads to rupture and intense inflammatory response to keratin debris


ETIOLOGY/PATHOGENESIS


Etiology



  • Tobacco use



    • Almost all men and women affected by SMOLD have history of tobacco use


    • It has been proposed that smoking leads to vitamin A deficiency, which results in abnormal squamous metaplasia


  • Inverted nipple



    • Many patients with SMOLD have inverted nipple


    • Inversion of nipple is more likely a result of retroareolar inflammation and fibrosis rather than a cause of the condition



      • Recurrent episodes of inflammation and healing with fibrosis lead to nipple retraction


  • Subareolar abscess formation



    • Keratinizing cells extend abnormally deep into lactiferous sinuses


    • Keratin becomes trapped and equivalent of an epidermal inclusion cyst is formed


    • If duct ruptures, keratin is released into surrounding tissue



    • Intense inflammatory response ensues, causing erythema, swelling, and pain


    • If involved duct is not removed, recurrences are common


CLINICAL ISSUES


Epidemiology



  • Incidence



    • Rare: < 1% of all breast biopsies


  • Age



    • Occurs at any adult age


  • Gender



    • Occurs in both females and males


Presentation



  • Patients initially present with erythematous painful subareolar mass



    • Usually mistaken for bacterial abscess



      • Initial lesions are sterile; inflammatory response is to keratin debris


    • Typical treatment is incision and drainage (I&D) and antibiotics for Staphylococcus species



      • Surgeons avoid surgery involving nipple due to cosmetic and functional concerns


    • Symptoms may be relieved temporarily


  • Recurrences are common



    • Often mystify patient and clinicians, as adequate treatment for an infection has been provided



      • Patients have been suspected of having Munchausen syndrome


    • Subsequent treatment may again be I&D and antibiotics


    • Secondary infections may occur


  • Fistula track may form after recurrences



    • Path of least resistance is below smooth muscle of areola


    • Track opens at edge of areola


    • Only 1 track is present


Treatment



  • Effective treatment requires surgical removal of keratin-producing epithelium



    • Wedge resection of nipple to remove involved duct may be performed


    • If a fistula track is present, it should be removed in continuity with involved duct


  • Antibiotics may be required for recurrent lesions with secondary infections



    • Secondary infections are often due to mixed anaerobic bacteria


    • Cultures are often helpful to establish type of bacteria and sensitivity to antibiotics


Prognosis



  • After effective surgical management, recurrences are uncommon


  • Termination of tobacco use may reduce likelihood of recurrence


IMAGE FINDINGS


Mammographic Findings



  • Patient may not tolerate compression due to painful mass


  • Location of lesion below nipple also makes it difficult to visualize


  • In some patients, a density may be present due to inflammatory reaction


Ultrasonographic Findings



  • May not be possible, as patient may not tolerate pressure from transducer


  • In some patients, a mass with irregular margins is present


MR Findings



  • MR may be better tolerated, as compression is not required


  • In 1 study, MR was effective in imaging abscess cavity and associated fistula track



MACROSCOPIC FEATURES


General Features



  • 1st specimen is often an I&D



    • Specimen consists of multiple fragments of tissue that cannot be oriented


  • If a definitive procedure is performed, there should be a small fragment of nipple skin and the underlying abscess cavity



    • If possible, sections should be oriented perpendicular to nipple skin


MICROSCOPIC PATHOLOGY


Histologic Features

Jul 6, 2016 | Posted by in PATHOLOGY & LABORATORY MEDICINE | Comments Off on Squamous Metaplasia of Lactiferous Ducts

Full access? Get Clinical Tree

Get Clinical Tree app for offline access