Breast

Mycobacterium ●● Acute and chronic inflammation, abscess,

granulomas, squamous metaplasia ●● Incision and drainage for abscess treatment

FAT NECROSIS

dystrophic calcification

GYNECOMASTIA

lescent boys ●● Imbalance between estrogen and androgen,

disordered end-organ response ●● Bilateral, if underlying endocrine abnor-

mality associated ●● Pseudogynecomastia: Breast enlargement due

to other tissues like muscle enlargement, obesity, diffuse neurofibromatosis, pseudoangiomatous stromal hyperplasia (PASH)

●● Subareolar mass, rubbery, white, ill-defined, mixed with adipose tissue

●● Early phase: Ductal epithelial hyperplasia, papillary and cribriform pattern, myoepithelial hyperplasia, cellular and edematous stroma

●● Late phase: Less epithelial proliferation, more collagenous stroma

JUVENILE HYPERTROPHY AND MACROMASTIA

●● Spontaneous, massive, painful, deforming, and rapid growth of female breast

yellow cut surface ●● Irregular ductal proliferation, epithelial

hyperplasia, edematous stroma, PASH may be associated

●● Treated with antiestrogen therapy or surgical reduction

FIBROADENOMA

freely mobile, size range 2-4 cm ●● Rubbery, bulging, and lobulated cut surface ●● Biphasic proliferation of epithelial, myoepi-

thelial, and stromal elements ●● Intracanalicular and pericanalicular sub-

types

TUBULAR ADENOMA

and myoepithelial cells, minimal stromal component

LACTATIONAL ADENOMAS

actively secreting ●● Seen during or shortly after pregnancy

JUVENILE FIBROADENOMA

●● Also known as cellular or giant fibroadenoma

●● Overlapping features with benign phyllodes tumor

ing a more hypercellular stroma and more epithelial hyperplasia

●● Intracanalicular, pericanalicular, and leaflike pattern (clefts lined by hyperplastic epithelium)

PHYLLODES TUMOR (CYSTOSARCOMA PHYLLODES)

mass ●● Tan-gray bulging and clefted cut surface ●● Low-grade spindle cell stroma, mitotically

active ●● Mitotic rate determines survival ●● Stromal cellularity and mitotic activity con-

centrated around ducts ●● Sarcomatous component may resemble

myofibroblasts, undifferentiated sarcoma, rhabdomyosarcoma, liposarcoma

NIPPLE DUCT ADENOMA

and adenosis ●● Differential diagnosis with syringocystad-

enoma papilliferum (extension to skin surface, exuberant plasma cell infiltrate)

HAMARTOMA

●● Fibrous or adipose tissue stroma, normal lobules/ducts (breast within a breast)

SECRETORY CARCINOMA

ETV6-NTRK3 gene fusion (also seen in cellular mesoblastic nephroma and infantile fibrosarcoma)

mic vacuoles

OTHER BREAST CANCERS

●● Second malignant tumors; in long term survivors of other childhood tumors

MESENCHYMAL LESIONS

Lipoma

Fibromatosis

●● Spindle cells arranged in broad sheets with thin-walled open blood vessels (positive for CD34 and beta-catenin)

nodular fasciitis, which are myofibroblastic lesions (positive for vimentin and smooth muscle actin)

Vascular tumors

Granular cell tumor

dant pale granular cytoplasm, central vesicular nuclei, prominent nucleoli

Hematopoietic lesions

●● These lesions include Burkitt lymphoma, granulocytic sarcoma, Rosai-Dorfman disease