Breast

• Rare, with at least 141 cases reported since 2002 (J Clin Pathol 2020;73:445)
• Female patients, parous or currently pregnant
• Mean age 35 years (range 19 - 57)

• Most commonly painful breast mass, nipple inversion or sinus formation (J Clin Pathol 2020;73:445)
• Nipple discharge, skin erythema and abscess
• Fever and leukocytosis
• Axillary lymphadenopathy

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• 30 year old woman with a fluctuant mass-like lesion (Case #462)
• 33 year old woman with recurrent breast abscess (Clin Infect Dis 2014;59:410)
• 37 year old woman with abscess and skin ulceration (Clin Microbiol Infect 2020 Jul 9 [Epub ahead of print])
• 52 year old woman with a tender left breast mass (Clin Case Rep 2018;6:2208)

• Observation
• Antibiotics:
  • Empirical antimicrobial therapy may be started prior to histologic diagnosis
  • Lipophilic antibiotics such as doxycycline, trimethoprim sulfamethoxazole, clarithromycin and rifampicin may be more effective (J Clin Microbiol 2015;53:2895)
  • Antibiotic susceptibility test should be performed
• Steroids
• Surgery including incision and drainage, excision and even mastectomy
• Combination of the above therapies

Contributed by Jessie M. Wu, M.B.Ch.B. and Gulisa Turashvili, M.D., Ph.D.


Contributed by Ankur Sangoi, M.D. (Case #462)

• Granulomatous mastitis due to other causes:
  • Infection (bacterial, fungal, parasitic):
    • Tuberculosis mastitis:
      • Necrotizing or nonnecrotizing granulomas composed of epithelioid histiocytes, Langerhans type multinucleated giant cells, eosinophils, lymphocytes and plasma cells commonly affecting ducts rather than lobules
      • Ziehl-Neelsen staining, culture or polymerase chain reaction can be used for establishing the diagnosis
  • Foreign body reaction:
    • Presence of foreign material
  • Fat necrosis:
    • Clinical history, vacuoles lacking gram positive bacilli
  • Autoimmune diseases:
    • Granulomatosis with polyangiitis:
      • Positive pANCA and cANCA, prominent vasculitis
    • Rheumatoid arthritis:
      • Joint symptoms, elevated rheumatoid factor, fibrinoid necrosis surrounded by lymphocytes and plasma cells
  • Sarcoidosis:
    • Non-necrotizing epithelioid granulomas, asteroid bodies, Schaumann bodies
  • Granulomatous lobular mastitis:
    • Diagnosis of exclusion, negative microbiologic examination, without known etiology
• Subareolar breast abscesses / squamous metaplasia of lactiferous ducts (SMOLD):
  • Strongly associated with smoking
  • Predominantly anaerobic organisms

A 35 year old woman presents with a right breast mass. Core biopsy shows empty appearing cystic spaces rimmed by neutrophils and an outer cuff of epithelioid histiocytes. Some vacuoles contain sparse, rod shaped bacilli. Which organism is most commonly associated with this type of granulomatous mastitis?

1. Corynebacterium diphtheriae
2. Corynebacterium kroppenstedtii
3. Mycobacterium tuberculosis
4. Staphylococcus aureus
5. Staphylococcus epidermidis

B. Corynebacterium kroppenstedtii. Cystic neutrophilic granulomatous mastitis is most commonly associated with Corynebacterium kroppenstedtii.

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Reference: Cystic neutrophilic granulomatous mastitis

Cystic neutrophilic granulomatous mastitis most commonly affects which of the following patient population?

1. Female smokers
2. Parous women
3. Postmenopausal women
4. Women living in endemic areas of tuberculosis
5. Women with a history of Corynebacterium diphtheriae infection

B. Parous women. Cystic neutrophilic granulomatous mastitis most commonly affects women who are currently pregnant or have been pregnant.

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Reference: Cystic neutrophilic granulomatous mastitis

Which of the following statements is true regarding cystic neutrophilic granulomatous mastitis?

1. Diagnosis may require matrix assisted laser desorption / ionization time of flight mass spectrometry
2. Gram positive bacilli are identified in nearly all cases
3. Resolution typically takes days
4. Usually presents as a painless palpable mass in postmenopausal women

A. Diagnosis may require matrix assisted laser desorption / ionization time of flight mass spectrometry. Diagnosis of cystic neutrophilic granulomatous mastitis may require culture, 16S rRNA gene sequencing or matrix assisted laser desorption / ionization time of flight mass spectrometry.

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Reference: Cystic neutrophilic granulomatous mastitis