Definition/General
Introduction:
Lymphocytic mastitis is a rare benign inflammatory condition of the breast characterized by a dense perilobular and periductal lymphocytic infiltrate
It is also known as diabetic mastopathy when it occurs in patients with type 1 diabetes.
Origin:
It is thought to be an autoimmune process.
Classification:
It is a subtype of chronic mastitis.
Epidemiology:
It typically affects premenopausal women with a long history of type 1 diabetes mellitus
It can also be seen in patients with other autoimmune diseases.
Clinical Features
Presentation:
Presents as a painless, hard, palpable mass that can be bilateral and multicentric
It can be clinically suspicious for malignancy.
Symptoms:
A painless, hard breast lump is the most common symptom.
Risk Factors:
Type 1 diabetes mellitus and other autoimmune diseases are the main risk factors.
Screening:
Mammography shows a dense, ill-defined mass
Ultrasound shows a hypoechoic, irregular mass with posterior acoustic shadowing.
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Gross Description
Appearance:
An ill-defined, extremely hard, white-gray mass.
Characteristics:
The lesion is very firm and fibrous.
Size Location:
Size is variable.
Multifocality:
Can be multifocal and bilateral.
Microscopic Description
Histological Features:
The key feature is a dense, perilobular and periductal lymphocytic infiltrate composed of mature B-cells
There is also prominent keloidal-type fibrosis and atrophic lobules
Epithelioid fibroblasts can be seen.
Cellular Characteristics:
The infiltrate is composed of small, mature lymphocytes.
Architectural Patterns:
A perilobular and periductal pattern of inflammation and fibrosis is characteristic.
Grading Criteria:
This is a benign inflammatory process.
Immunohistochemistry
Positive Markers:
The lymphocytes are predominantly B-cells (CD20 positive).
Negative Markers:
Not typically required for diagnosis.
Diagnostic Utility:
IHC can be used to confirm the B-cell nature of the infiltrate.
Molecular Subtypes:
Molecular subtyping is not relevant for this benign condition.
Molecular/Genetic
Genetic Mutations:
This is a benign 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, but it can recur
It 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
Lymphoma.
Distinguishing Features:
Invasive carcinoma has malignant epithelial cells
Lymphoma has a monotonous infiltrate of atypical lymphoid cells.
Diagnostic Challenges:
The main challenge is to distinguish it from invasive carcinoma due to the clinical and radiological findings
The dense fibrosis can also make it difficult to interpret on core biopsy.
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]