Image of the Quarter (2015-5)
A good example of a Juvenile fibroadenoma
13 year old female - large (3 cm) clinically benign lump left breast.
The tumour shows a low power pattern of a biphasic lesion with a rounded interface with surrounding fat, evenly spaced glands, and a cellular stroma. The 'Mouse-over' shows epithelial hyperplasia and stromal cellularity.
These further H&Es show show two patterns of stromal cellularity: Image A shows a more open pattern (mitoses were not easy to find in these areas); Image B (Mouse over) shows a more storiform pattern where mitoses could be found relatively easily.
The final pair of views show stromal hypercellularity (storiform pattern - type B above) with focal stromal mitoses (Mouse-over).
- Juvenile fibroadenoma is a very uncommon variant of a benign biphasic tumour usually seen in adolescents and younger adults.
- Hallmark features:
- A pushing margin
- Evenly balanced distribution between stroma and epithelium.
- Stromal hypercellularity which is generally even - in contrast to phyllodes tumours where it may be patchy
- Stromal mitoses may be frequent in adolecents but are uncommon in young adults
- They should be managed as regular fibroadenomas following discussion at a multidisciplinary meeting. The crucial differential diagnosis is benign pyhllodes tumour.
In this case stromal mitoses were quite patchily distributed with areas depicted in image A (see above) lacking mitoses and the more storiform areas showing mitotic activity.<