BENIGN TUMORS

Fibroadenoma

• is the most common benign tumor of the female breast
• it occurs at any age within the reproductive period-highest incidence in young women before 30 years of age
• grossly- freely movable, well circumscribed, firm nodule
• on section the tumor is uniformly grey-white, firm nodular
• usually between 1-5 cm in diameter
• infrequently, FA may grow to very massive proportions -called giant fibroadenoma
• histologically- fibroadenoma is characterized by proliferation of both glandular and stromal elements-the tumor exists in two variants- pericanalicular and intracanalicular fibroadenoma -often overlapping patterns

• pericanalicular-fibroblastic hypercellular stroma encloses glandular and cystic epithelial spaces in concentric manner
• intracanalicular-connective tissue stroma reveals more active proliferation with compression of the epithelial structures, glandular lumina are compressed into narrow strands or slit-like irregular clefts

Phyllodes tumor

• less common than FA
• large bulky tumor lobulated and cystic- they have been designated cystosarcoma phyllodes - the lesion can be both benign and malignant-
• grossly: lobulated, cystic tumors, the tumor may cause a distortion of the breast- produce a bulky mass, even pressure necrosis of the overlying skin- this clinical behaviour does not imply malignancy
• histologically: more cellular myxoid stroma than in fibroadenomas
• increased stromal cellularity, high mitotic activity and anaplasia- imply more aggressive clinical behaviour and transformation to malignancy -rapid increase in size and invasive growth to adjacent breast tissue

Lactating adenoma

• patients are young- pregnant or nursing
• associated with rapid increase in size- benign -may be even multiple
• histologically composed of well differentiated glandular structures- lobular arrangement, well-circumscribed by fibrous capsule

Intraductal papilloma

• benign tumor originating in a major lactiferous duct- presents with bloody nipple discharge -most are less than 1 cm in diameter
• grossly-papillary mass projecting into the lumen of a large duct
• papilloma are generally solitary, less than 1 cm in diameter
• located in the subareolar region
• most commonly during the fifth and sixth decade of life
• histologically- numerous delicate papillae composed of fibrovascular stroma and covered by a layer of epithelial and myoepithelial cells -epithelial cells line the luminal aspect of the papillae and a myoepithelial cell layer is invariably present between the epithelial cells and the basement membranes

Papillomatosis

• is defined as a proliferation of papillary fronds supported by fibrovascular stalks within multiple terminal duct-lobular units
• patients are younger than those with solitary papillomas- nipple discharge in about one third of patients
• clinically- in some cases accompanied by atypical ductal hyperplasia and increased incidence of cancer

Granular cell tumor

• is a rare benign tumour of the breast-
• is a well-recognized lesion which occurs in a wide variety of visceral and cutaneous sites
• untill recently- the histogenesis of the tumour has been controversial resulting in a descriptive name (granular cell tumour) composed of uniform cells with granular eosinophilic cytoplasm- neural origin is likely
• may occur in all ages
• grossly: resembles breast carcinoma - hard mass with skin retraction, fibrous consistency and fixation to pectoral fascia
• histologically: GCT is composed of infiltrating cords and clusters of uniformly rounded or polygonal cell with coarsely granular cytoplasm- immunoreactivity for S-100 protein

Category: Pathology Notes