Pathology Outlines - Hamartoma May have smooth muscle, cartilage or pseudoangiomatous stromal hyperplasia (PASH) (Histopathology 2022;80:304) Lesions with prominent myoid changes called myoid hamartomas (Geburtshilfe Frauenheilkd 2012;72:412) 2 variants:
Pathology Outlines - Atypical lobular hyperplasia Lower risk of upgrade than lobular carcinoma in situ 4 - 5 times usual risk of carcinoma, higher in ipsilateral breast, higher if age 50 years; risk increased further if ductal involvement (Am J Surg Pathol 2002;26:421, Cancer 2007;109:180, Hum Pathol 1988;19:201)
Pathology Outlines - Fibroadenoma Breast nonmalignant - Fibroadenoma is a benign biphasic tumor composed of a proliferation of both glandular epithelial and stromal components of the terminal duct lobular unit
Pathology Outlines - Hidradenitis suppurativa A component of several autoinflammatory syndromes, including PASH (pyoderma gangrenosum, acne and hidradenitis suppurativa) and PAPASH (pyoderma gangrenosum, acne, pyogenic arthritis and hidradenitis suppurativa) (Int J Dermatol 2017;56:811)
Pathology Outlines - Atypical ductal hyperplasia Atypical ductal hyperplasia is an intraductal clonal epithelial cell proliferation with similar histologic features to (but insufficient involvement or volume for the diagnosis of) low grade ductal carcinoma in situ (DCIS)
Pathology Outlines - Paget disease 2 theories on the pathogenesis: Epidermotropic theory (most widely accepted): Paget cells are DCIS cells that migrate along the basement membrane of the nipple, supported by the presence of DCIS deeper in the breast identical to Paget cells in almost all cases; migration may be mediated through a motility factor heregulin α, produced by keratinocytes and exerting its effect via the HER2