Definition/General
Introduction:
Plasma cell mastitis is a benign inflammatory condition of the breast characterized by a prominent plasma cell infiltrate in the periductal stroma
It is considered a form of chronic mastitis and is often associated with duct ectasia.
Origin:
It is thought to be a reaction to the contents of dilated ducts (duct ectasia).
Classification:
It is a subtype of chronic mastitis.
Epidemiology:
It is most common in middle-aged and older women.
Clinical Features
Presentation:
Presents as a palpable, ill-defined, subareolar mass
Nipple retraction can occur, mimicking carcinoma.
Symptoms:
A painless or mildly tender breast lump is the most common symptom.
Risk Factors:
Duct ectasia is the main risk factor.
Screening:
Mammography can show a spiculated mass or architectural distortion.
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Gross Description
Appearance:
An ill-defined, firm, gray-white area of induration.
Characteristics:
The tissue is fibrotic.
Size Location:
Usually located in the subareolar region.
Multifocality:
Can be multifocal.
Microscopic Description
Histological Features:
The key feature is a dense, periductal inflammatory infiltrate composed predominantly of mature plasma cells
Lymphocytes and histiocytes are also present
It is often seen in the context of duct ectasia.
Cellular Characteristics:
Sheets of plasma cells with eccentric nuclei and clock-face chromatin are characteristic.
Architectural Patterns:
A periductal inflammatory infiltrate is characteristic.
Grading Criteria:
This is a benign inflammatory process.
Immunohistochemistry
Positive Markers:
The plasma cells are polyclonal, showing a mixture of kappa and lambda light chain expression.
Negative Markers:
Not applicable.
Diagnostic Utility:
IHC for kappa and lambda light chains can be used to confirm the polyclonal nature of the plasma cell infiltrate and to rule out a plasmacytoma.
Molecular Subtypes:
Not applicable.
Molecular/Genetic
Genetic Mutations:
Not applicable.
Molecular Markers:
No specific molecular markers are routinely used for diagnosis.
Prognostic Significance:
This is a benign condition and is not associated with an increased risk of breast cancer.
Therapeutic Targets:
No treatment is required unless it forms a mass that needs to be distinguished from carcinoma.
Differential Diagnosis
Similar Entities:
Invasive carcinoma
Plasmacytoma.
Distinguishing Features:
Invasive carcinoma has malignant epithelial cells
A plasmacytoma is a monoclonal proliferation of plasma cells.
Diagnostic Challenges:
The main challenge is to distinguish it from a plasmacytoma, which is rare in the breast
Light chain IHC is key.
Rare Variants:
Not applicable.
Sample Pathology Report
Template Format
Sample Pathology Report
Complete Report: This is an example of how the final pathology report should be structured for this condition.
Specimen Information
[specimen type], measuring [size] cm in greatest dimension
Diagnosis
[diagnosis name]
Classification
Classification: [classification system] [grade/type]
Histological Features
Shows [architectural pattern] with [nuclear features] and [mitotic activity]
Size and Extent
Size: [X] cm, extent: [local/regional/metastatic]
Margins
Margins are [involved/uninvolved] with closest margin [X] mm
Lymphovascular Invasion
Lymphovascular invasion: [present/absent]
Lymph Node Status
Lymph nodes: [X] positive out of [X] examined
Special Studies
IHC: [marker]: [result]
Molecular: [test]: [result]
[other study]: [result]
Final Diagnosis
Final diagnosis: [complete diagnosis]