Breast-nonmalignant

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Breast-nonmalignant

Benign tumors / changes

Hamartoma of breast

Reviewer: Hind Nassar, M.D. in January 2009 (see Authors page)

Revised: 7 October 2012, last major update April 2010

Definition

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● Well circumscribed, often encapsulated mass composed of all components of breast tissue

Terminology

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● Also called fibroadenolipoma, adenolipoma

Epidemiology

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● Rare

● Mean age 45 years

● Rare in teenagers (Breast J 2009;15:515)

Etiology

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● May be a malformation, not a neoplasm

Clinical features

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● Xray: clearly demarcated lesion on mammography

Case reports

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● 35 year old woman with coexisting DCIS and infiltrating ductal carcinoma (Breast J 2006;12:368)

● 46 year old woman with myxoid hamartoma and chondroid metaplasia (Malays J Pathol 2009;31:77)

● 53 year old woman with coexisting LCIS and invasive lobular carcinoma (J Clin Path 2002;55:76)

● 57 year old woman with bilateral tumors in axillary accessory mammary glands (APMIS 2006;114:77)

● Case with atypical stromal cells (Pathologica 2007;99:434)

● Cases with coexisting adenofibroma/ALH and infracted fibroadenoma (Arch Pathol Lab Med 2003;127:e151)

● Case designated a choristoma (Hum Pathol 1985;16:739)

● Cases with DCIS (J Clin Path 2002;55:541)

Treatment

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● Excision; does not recur if negative margins

Gross description (Macroscopy)

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● Well circumscribed mass of firm, rubbery, white tissue, 1-8 cm, more distinctive grossly than microscopically

Gross images

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Various images

Ovoid yellow Fat, glandular elements Smooth and glistening mass

white mass and stroma in

pregnant patient

Micro description (Histopathology)

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● Sharply circumscribed mass of disordered breast ducts and lobules

● Ducts often dilated, accompanied by fibrosis

● May have smooth muscle, adipose tissue, hyaline cartilage, pseudoangiomatous hyperplasia

● May resemble gynecomastia due to lack of ducts

● Myoid hamartoma: also has smooth muscle stroma; may contain epithelioid cells (Arch Pathol Lab Med 1996;120:676, Hum Pathol 1985;16:212)

Micro images

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Dilated ducts and fibrous stroma Breast ducts and adipose tissue (adenolipoma)

Rounded border and fibrous capsule Epithelial and mesenchymal components

Well circumscribed mass with adipose

normal lobules, cystically dilated ducts



Various images



Various images



With LCIS and invasive                     With high grade DCIS

lobular carcinoma



Well defined fibrous tumor              Adipose tissue plus ducts               With ductal hyperplasia

with ducts separated by                   resembling gynecomastia              resembling gynecomastia

connective tissue



Smooth muscle bundles                  Hyaline cartilage and

(arrows) and fibrous tissue             adipose tissue



Myoid hamartoma: H&E and smooth muscle actin+

Cytology description

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● Moderately cellular, sheets of bland ductal cells and lobular units, bipolar stromal nuclei, varying amounts of adipose tissue, less prominent stromal fragments, occasional apocrine and foamy cells, no atypia

● Findings are not specific (Cancer 2003;99:255, Cytopathology 2003;14:195)

Positive stains

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●

Negative stains

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●

Electron microscopy descriptions

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●

Electron microscopy images

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Molecular / cytogenetics description

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●

Molecular / cytogenetics images

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Differential Diagnosis

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● Gynecomastia-like changes: not sharply circumscribed, merges gradually with normal breast tissue, no lobules present

Additional references

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● J Clin Path 2002;55:951, Stanford University

End of Breast-nonmalignant > Benign tumors / changes > Hamartoma

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