Pathology Outlines - PAS (Periodic acid-Schiff) PAS (Periodic acid-Schiff) is a special stain, not an immunostain, that stains basement membrane (normal and in tumors), glycogen, some mucins and mucopolysaccharides
Pathology Outlines - Myofibroblastoma Pseudoangiomatous stromal hyperplasia (PASH): Empty, anastomosing spaces within collagen Usually not mass forming Rb1 positive by immunohistochemistry and lacks del 13q14 Similar immunoprofile (CD34 positive, desmin positive [variable], ER, PR and AR positive) Solitary fibrous tumor: STAT6 positive (Pathol Res Pract 2018;214:1544)
Pathology Outlines - Hamartoma Hamartoma is a well circumscribed, often encapsulated mass composed of normal but disorganized components of breast tissue
Pathology Outlines - Anatomy PASH (pseudoangiomatous stromal hyperplasia) is specific to breast Int ra lobular Surrounds acini in TDLUs Compared to interlobular stroma, looser in appearance or even myxoid Often small numbers of inflammatory cells Lesions arising here are biphasic involving epithelial and stromal components, including fibroadenoma, phyllodes tumor
Pathology Outlines - Schwannoma May contain stromal fascicular PASH-like pattern with nuclear palisading Differentiating features, if present Benign epithelial component with intracanalicular, pericanalicular or leaf-like architecture Infiltrative growth Differentiating immunohistochemistry Positive: CD34 (variable), smooth muscle markers (variable: SMA, desmin, calponin)
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Pathology Outlines - Gynecomastia Breast nonmalignant - Gynecomastia - benign enlargement of the male breast, typically presenting as a palpable subareolar mass
Pathology Outlines - Fibromatosis-like Fibromatosis-like metaplastic carcinoma is a variant of metaplastic carcinoma with low grade, bland, spindle cells histologically resembling fibromatosis