J Korean Surg Soc.  2009 Jan;76(1):56-60. 10.4174/jkss.2009.76.1.56.

Extensive Squamosu Metaplasia Mimicking Squamous Cell Carcinoma in Fibroadenoma

• Cha EJ
• Choi KH
• Youn HJ
• Kim DS
• Moon WS

• KMID: 2040606
• DOI: http://doi.org/10.4174/jkss.2009.76.1.56

Abstract

We report a fibroadenoma with extensive squamous metaplasia in the breast. A 21-year-old woman presented with a mass of the left breast. Breast ultrasonography showed a 1.8x1.7 cm sized, well-circumscribed mass in left subareolar region. The mass was excised. Grossly, the mass was well circumscribed and the cut surfaces were grayish-white in color and elastic in consistency. Microscopically, the breast lesion showed the histological features of fibroadenoma. There were areas of extensive squamous metaplasia seen as isolated clusters or involving duct. But some metaplastic clusters surrounded by fibrous stroma were compressed and distorted and separation of cells into isolated clusters mimicked invasive carcinoma. Co-expression of CK 5/6, high molecular weight CK and p63 in areas of squamous metaplasia and normal myoepithelial cells supported myoepithelial cell origin of metaplastic cells.

Keyword

Breast; Fibroadenoma; Squamous metaplasia

MeSH Terms

Breast
Carcinoma, Squamous Cell
Female
Fibroadenoma
Humans
Metaplasia
Molecular Weight
Ultrasonography, Mammary
Young Adult

Figure

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  Fig. 1 Breast ultrasonography showing a well-circumscribed mass in left subareolar region.

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  Fig. 2 (A) Extensive squamous metaplasia showing large sheet, isolated nest or involving duct (H&E stain, ×100). (B) Small clusters of epithelial cells surrounded by fibrous tissue and fibrous distortion resembled infiltrative carcinoma (H&E stain, ×400). (C) Mitotic activity is identified up to 4/high power field in some area of squamous metaplasia (H&E stain, ×400). (D) Involving ducts shows transition zone with squamous metaplastic cells apparently arising from basal cells (H&E stain, ×100).

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  Fig. 3 Immunostaining for p63 (A, ×100), CK 5/6 (B, ×100) and HMWCK (C, ×100) was strong in areas of squamous metaplasia and in basal cells of duct. Ki-67 proliferation rate was less than 5% (D, ×400). Avidin-biotin-conjugate (ABC) method.

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