Fibroadenomas
Clinical basics
- Present as smooth mobile lumps
- Common, especially in younger women
- " Old" lesions picked up by screening - calcified - see below
- Concerns should be raised about possible Phyllodes Tumour if:
- Patient older than 40 years
- Lesion larger than 4 cm
- History of recent growth
Fibroadenoma showing circumscribed margins, even distribution of epithelial and stromal components and low stromal cellularity
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Fibroadenomas showing circumscribed margins, even distribution of epithelial and stromal components and low stromal cellularity - particularly the upper lesion
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Fibroadenomas - 'must know' histology & FNA basics
- Use low power scanning to determine:
- the basic pattern - pericanalicular or intracanalicular
- edge of lesion (pushing or infiltrative) - should be pushing
- balance between stroma and epithelium - should be even
- to pick out areas of stromal hypercellularity
- The stroma can be cellular particularly in younger patient's lesions - but it's usually uniform
- The occasional stromal mitosis is acceptable in a younger patient's lesion but take advice
- Uneven stromal cellularity in a core biopsy may be a pointer to a Phyllodes Tumour
- A good core biopsy with clinical & imaging information should allow the following decision tree to be followed:
- Do not recommend excision
- Recommend excision but not wide excision
- Recommend excision with a margin - this final scenario is uncommon
- In excised specimens:
- Sample generously, particularly in larger lesions from older patients
- Phyllodes changes can be patchy but often correspond to macroscopically different areas
- FNA cytology of fibroadenomas can be very tricky:
- False positives & false negatives can occur
- Scan the smear at low power to pick up the fibroadenoma 'pattern'
- Beware the false positive in an FNA from a younger (< 25 yrs) patient - if it's clinically benign it usually is
- Trying to distinguish a fibroadenoma from a phyllodes tumour on an FNA is largely a waste of time: advise that the lesion is biphasic and ask for a core
The distinction between intracanalicular and pericanalicular patterns of fibroadenoma is
illustrated in the series of three images immediately below.
The intracanalicular pattern is a consequence of relative stromal overgrowth. This is the pattern of
biphasic lesion that is also seen in phyllodes tumours and a critical assessment of the stroma is especially
important in this pattern of lesion.
Intracanalicular fiobroadenoma. Pass the mouse over the image to view the less common pericanalicuar variant.
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Intracanalicular fibroadenoma. Pass the mouse over these images to view the pericanalicular variant - specialised stroma (A), non-specialised stroma (B).
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Old Fibroadenoma (core biopsy) showing very low stromal cellularity. These lesions
are often picked up at screening as calcified opacities
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The calcs in the mammogram for these cores were regarded as very suspicious of malignancy. Such calcification in an old fibroadenoma is not uncommon in screening cases
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PAP stained FNA from a fibroadenoma - detail of a large stromal fragment (blue arrow), vessel fragment (red arrow) and small epthelial group (yellow arrow).
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PAP (Left) & Giemsa (Right) preparations of FNA from a fibroadenoma. Note the
uniformity in the epithelial group (red circle) and bare nuclei (red arrows) in top left photomicrograph.
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FNA from a clinical fibroadenoma supported by imaging from a 19 year old woman.
The dispersed pattern gives an initially worrying appearance and could lead to
a mistaken diagnosis of malignancy. Look for the biphasic population of epithelial cells
and bare nuclei in the background. Stromal fragments would have been reassuring but were not present.
The case was discussed in the Department and a C2 designation made
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Further views of the same case. Green arrows (lower left) point to myoepithelial cells within a benign epithelial group. The green circles highlight some of the many background bare nuclei.
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