Definition/General
Introduction:
Solid papillary carcinoma (SPC) is a rare papillary breast cancer characterized by a solid growth pattern with fibrovascular cores
It is considered an indolent, low-grade malignancy
It can be in situ (if confined) or invasive.
Origin:
It arises from the ductal epithelium.
Classification:
SPC is a form of papillary carcinoma
When confined within a fibrous capsule, it is considered in situ
When it extends beyond the capsule, it is invasive.
Epidemiology:
It typically affects older, postmenopausal women
It accounts for about 1% of all breast cancers.
Clinical Features
Presentation:
Presents as a palpable, well-circumscribed mass
Nipple discharge can occur.
Symptoms:
A painless breast lump is the most common symptom.
Risk Factors:
The risk factors are similar to those for other types of breast cancer.
Screening:
Mammography shows a well-defined, round or lobulated mass.
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Gross Description
Appearance:
A well-circumscribed, soft, friable mass.
Characteristics:
The size is variable
The cut surface is tan-pink and can be hemorrhagic.
Size Location:
Usually located in the central part of the breast.
Multifocality:
Usually unifocal.
Microscopic Description
Histological Features:
The lesion is composed of multiple, well-circumscribed, expansile nodules with a solid growth pattern
The tumor cells are arranged in sheets and nests, separated by delicate fibrovascular cores
The key feature is the absence of a myoepithelial layer.
Cellular Characteristics:
The cells are monotonous, with low-grade, oval to spindle-shaped nuclei, often with nuclear grooves
The cytoplasm is scant
The cells often show neuroendocrine features.
Architectural Patterns:
A solid, expansile growth pattern is characteristic.
Grading Criteria:
These are typically low-grade tumors.
Immunohistochemistry
Positive Markers:
The epithelial cells are positive for cytokeratins and are almost always ER-positive
They frequently show positivity for neuroendocrine markers like synaptophysin and chromogranin A.
Negative Markers:
The key finding is the absence of myoepithelial markers (e.g., p63, calponin)
HER2 is usually negative.
Diagnostic Utility:
IHC for myoepithelial markers is essential for diagnosis
Neuroendocrine markers are helpful.
Molecular Subtypes:
Most are of the luminal subtype.
Molecular/Genetic
Genetic Mutations:
Not well characterized.
Molecular Markers:
No specific molecular markers are routinely used for diagnosis.
Prognostic Significance:
SPC has an excellent prognosis, even when invasive
Lymph node metastasis is rare.
Therapeutic Targets:
Treatment is primarily surgical excision
Endocrine therapy may be used for ER-positive tumors.
Differential Diagnosis
Similar Entities:
Encapsulated papillary carcinoma
Papillary DCIS
Neuroendocrine carcinoma.
Distinguishing Features:
Encapsulated papillary carcinoma has a more complex papillary architecture
Papillary DCIS is confined to ducts
Neuroendocrine carcinoma is a broader category.
Diagnostic Challenges:
The main challenge is to assess for invasion, which can be subtle.
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]