Fibroadenoma variants

See also 'Fibroadenoma' - main page

Variant forms (all benign):

• Juvenile Fibroadenoma



• Giant Fibroadenoma



• Complex Fibroadenoma



• Tubular Adenoma



• Lactating Adenoma

• A rare variant form of fibroadenoma usually seen in adolescents and young adult women
• History of rapid growth common - may distort the breast
• Stromal/epithelial balance not altered (in contrast to Phyllodes Tumours)
• Stromal and epithelial hyperplasia characteristic
• In contrast to benign Phyllodes Tumours (the critical differential):



• Stromal cellularity is less pronounced
• Stromal cellularity does NOT show peri-ductal concentration
• There is no stromal cytological atypia
• Stromal mitoses are uncommon

Biopsy of a juvenile fibroadenoma - note both stromal and epithelial hyperplasia

Juvenile fibroadenoma - note both stromal and epithelial hyperplasia. The mitosis in the bottom right image is an infrequent finding in these cases

The term 'Giant Fibroadenoma' lacks a consistent definition and is not a true histopathological or clinico-pathological entity. It has been used as synonymous with Juvenile Fibroadenoma by some writers but as simply a large/very large fibroadenoma with usual histology by others.

Complex Fibroadenoma

• Same underlying architecture as a common fibroadenoma
• Extensive superimposed 'fibrocystic-type' changes on glandular elements:


• Apocrine metaplasia
• Sclerosing adenosis
• Cyst formation

Core biopsy of a complex fibroadenoma - so named because of the superimposed benign fibrocystic-like changes on the background architecture of a fibroadenoma.

Tubular Adenoma

• Same basic architecture as a common fibroadenoma but shows striking tubular proliferation with little intervening stroma
• Hybrid forms with areas of common fibroadenoma adjacent to tubular areas are not uncommon
• FNAs from tubular adenomas can be very cellular

Excision biopsy of a tubular adenoma.

Excision biopsy of a tubular adenoma - example 2.

• The strict use of this term applies to a mass lesion composed of a compact aggregate of lobules showing secretory hyperplasia
• The term is also applied (incorrectly) to lactational change superimposed upon a pre-existing fibroadenoma
• Both scenarios are a common cause of an enlarging clinically benign breast lump during pregnancy/lactation
• FNA appearances can be mistaken for malignant atypia - check the clinical history

Excision biopsy of a lactating adenoma.

FNA from a lactating adenoma. The rather messy background, irregularity of cell groups and cytological atypia could give rise to a mistaken suspicion of malignancy. Note cytoplasmic vacuolation.

Lactating adenomas may uncommonly undergo infarction which, in the early phase, gives rise to enlargement of the lesion and may precipitate clinical presentation. The following images are from a core biopsy of such a lesion:

Core biopsy from an infarcted lactating adenoma. The infarcted area is on the left hand side of the picture

Core biopsy from an infarcted lactating adenoma. Note the following areas:
A - Edge of infarcted central zone; B - Zone of haemosiderin-laden macrophages around periphery of infarct;
C- zone of peripheral fibrosis; D - Subcapsular viable adenoma showing lactational change; E - Peripheral fibrous 'capsule'

Infarcted lactating adenoma:
Left hand image - interface between infarcted central zone and haemisiderin-laden macrophage zone Right hand image from left to right - peripheral fibrosis; subcapsular viable zone; 'capsule'.

Return to top of page