Definition/General
Introduction:
Chronic mastitis is a long-standing inflammation of the breast
It is a general term that includes several specific entities, such as plasma cell mastitis and lymphocytic mastitis.
Origin:
The cause is often unknown, but it can be related to duct ectasia, autoimmune processes, or unresolved acute mastitis.
Classification:
It is a benign inflammatory condition.
Epidemiology:
It is most common in middle-aged and older women.
Clinical Features
Presentation:
Presents as a firm, ill-defined, palpable mass, often in the subareolar region
Nipple retraction can occur, mimicking carcinoma.
Symptoms:
A painless or mildly tender breast lump is the most common symptom.
Risk Factors:
Duct ectasia is a common predisposing factor.
Screening:
Mammography can show a spiculated mass or architectural distortion, which can be suspicious for malignancy.
Master Chronic Mastitis Pathology with RxDx
Access 100+ pathology videos and expert guidance with the RxDx app
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 chronic inflammatory infiltrate composed of lymphocytes and plasma cells
The infiltrate is often centered around ducts and lobules
Fibrosis is also a prominent feature.
Cellular Characteristics:
Lymphocytes and plasma cells are the dominant cell types
In plasma cell mastitis, sheets of mature plasma cells are seen.
Architectural Patterns:
A periductal and perilobular inflammatory infiltrate is characteristic.
Grading Criteria:
This is a benign inflammatory process.
Immunohistochemistry
Positive Markers:
Immunohistochemistry is not typically required for diagnosis.
Negative Markers:
Immunohistochemistry is not typically required for diagnosis.
Diagnostic Utility:
IHC is not used for diagnosis, but can be used to confirm the polyclonal nature of the plasma cell infiltrate if there is a concern for plasmacytoma.
Molecular Subtypes:
Molecular subtyping is not relevant for this benign inflammatory condition.
Molecular/Genetic
Genetic Mutations:
Chronic mastitis is an inflammatory condition and is not associated with specific genetic mutations.
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:
Treatment is usually conservative
Surgery may be performed to exclude malignancy.
Differential Diagnosis
Similar Entities:
Invasive carcinoma
Granulomatous mastitis
Lymphoma.
Distinguishing Features:
Invasive carcinoma has malignant epithelial cells
Granulomatous mastitis has granulomas
Lymphoma has a monotonous infiltrate of atypical lymphoid cells.
Diagnostic Challenges:
The main challenge is to distinguish chronic mastitis from invasive carcinoma, as it can form a hard, irregular mass.
Rare Variants:
There are no specific rare variants.
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]