Fibroadenomas


Clinical basics


Fibroadenoma showing circumscribed margins, even distribution of epithelial and stromal components and low stromal cellularity
Low power view of a fibroadenoma - well circumscribed boundary with an even balance between glands and stroma



Fibroadenomas showing circumscribed margins, even distribution of epithelial and stromal components and low stromal cellularity - particularly the upper lesion
Low power view of a fibroadenoma - well circumscribed boundary with an even balance between glands and stroma The stroma is of low cellularity




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.
Pericanalicular fibroadenoma

Intracanalicular fibroadenoma. Pass the mouse over these images to view the pericanalicular variant - specialised stroma (A), non-specialised stroma (B).
Pericanalicular fibroadenoma Pericanalicular fiboadenoma


Old Fibroadenoma (core biopsy) showing very low stromal cellularity. These lesions are often picked up at screening as calcified opacities
Low power view of a fibroadenoma - well circumscribed boundary with an even balance between glands and stroma The stroma is of low cellularity


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
Old fibroadenoma core - note low stromal cellularity The calcs are within and adjacent to glandular elements
The calcs are within and adjacent to glandular elements Specimen x ray of one of the fragments showing a group of irregular calcs





PAP stained FNA from a fibroadenoma - detail of a large stromal fragment (blue arrow), vessel fragment (red arrow) and small epthelial group (yellow arrow).
FNA from a fibroademoma - detail of stromal fragment


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.
PAP stained FNA from a fibroadenoma Giemsa stained FNA from a fibroadenoma
PAP stained FNA from a fibroadenoma Giemsa stained fNA from a fibroadenoma



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
PAP stained FNA from a fibroadenoma showing a dispersed pattern


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.
PAP stained FNA from a fibroadenoma Giemsa stained FNA from a fibroadenoma
PAP stained FNA from a fibroadenoma Giemsa stained fNA from a fibroadenoma

Return to top of page