Anatomic Pathology: Cytopathology

• The origin of lactating adenomas, though controversial, is believed to be de novo or a variant of a preexisting tubular adenoma or fibroadenoma that reflects the morphologic changes resulting from the physiologic state of pregnancy.

• Cytologic features of lactating adenomas include the following: dissociated epithelial cells stripped of their cytoplasm (round, naked nuclei with prominent nucleoli) with small clusters of cells having frayed secretory cytoplasm; larger groups containing epithelial cells with prominent nucleoli and abundant vacuolated cytoplasm; microtissue fragments showing features of lobular hyperplasia; and a background of secretory proteinaceous debris.

• Occasional pregnancy-related or lactating adenomas consist of large, dissociated cells with nuclear pleomorphism and prominent irregular nucleoli and could potentially be confused with malignancy if the other features of these lesions are not appreciated. Although most ductal carcinomas show a greater degree of nuclear atypia and dyshesion than do these pregnancy-related benign lesions, sometimes, the distinction may be difficult; however, fine needle aspiration is an effective method in the diagnosis of carcinoma of breast during pregnancy and lactation. Utilizing fine needle aspiration as a first line of investigation, the need for an unnecessary invasive surgery may be avoided in these women.

• Subareolar abscess may be seen in all age groups but is most common in nonlactating premenopausal women. It has also been reported to rarely occur in men. It is characterized by repeated episodes of abscess formation in the subareolar area. It is thought to result from duct blockage secondary to squamous metaplasia. The hallmark findings are numerous squamous cells in a background of acute inflammatory cells. Multinucleated giant cells represent a foreign body reaction to keratinous material. Atypia of ductal cells and granulation-type tissue are other findings. The differential diagnosis includes conditions such as acute mastitis, keratinous (epidermal) cyst, and pilomatrixoma. Acute suppurative mastitis differs only by the absence of squamous cells. A ruptured and inflamed keratinous (epidermal) cyst is identical to subareolar abscess cytologically. The classic clinical presentation of subareolar abscess and the peripheral rather than subareolar location of epidermal cyst help differentiate the two lesions. Pilomatrixoma also shares cytologic features with sebaceous adenoma, including the presence of anucleated squames; however, clusters of basaloid cells are often identified in smears of pilomatrixomas. Subareolar abscess may be seen in all age groups but is most common in nonlactating premenopausal women. It has also been reported to rarely occur in men. It is characterized by repeated episodes of abscess formation in the subareolar area. It is thought to result from duct blockage secondary to squamous metaplasia. The hallmark findings are numerous squamous cells in a background of acute inflammatory cells. Multinucleated giant cells represent a foreign body reaction to keratinous material. Atypia of ductal cells and granulation-type tissue are other findings. The differential diagnosis includes conditions such as acute mastitis, keratinous (epidermal) cyst, and pilomatrixoma. Acute suppurative mastitis differs only by the absence of squamous cells. A ruptured and inflamed keratinous (epidermal) cyst is identical to subareolar abscess cytologically. The classic clinical presentation of subareolar abscess and the peripheral rather than subareolar location of epidermal cyst help differentiate the two lesions. Pilomatrixoma also shares cytologic features with sebaceous adenoma, including the presence of anucleated squames; however, clusters of basaloid cells are often identified in smears of pilomatrixomas. Subareolar abscess may be seen in all age groups but is most common in nonlactating premenopausal women. It has also been reported to rarely occur in men. It is characterized by repeated episodes of abscess formation in the subareolar area. It is thought to result from duct blockage secondary to squamous metaplasia. The hallmark findings are numerous squamous cells in a background of acute inflammatory cells. Multinucleated giant cells represent a foreign body reaction to keratinous material. Atypia of ductal cells and granulation-type tissue are other findings. The differential diagnosis includes conditions such as acute mastitis, keratinous (epidermal) cyst, and pilomatrixoma. Acute suppurative mastitis differs only by the absence of squamous cells. A ruptured and inflamed keratinous (epidermal) cyst is identical to subareolar abscess cytologically. The classic clinical presentation of subareolar abscess and the peripheral rather than subareolar location of epidermal cyst help differentiate the two lesions. Pilomatrixoma also shares cytologic features with sebaceous adenoma, including the presence of anucleated squames; however, clusters of basaloid cells are often identified in smears of pilomatrixomas. Studies suggest an association between cigarette smoking and breast abscesses. Studies suggest an association between cigarette smoking and breast abscesses. Studies suggest an association between cigarette smoking and breast abscesses. Studies suggest an association between cigarette smoking and breast abscesses. Studies suggest an association between cigarette smoking and breast abscesses. Studies suggest an association between cigarette smoking and breast abscesses. It is important to provide a definitive diagnosis of subareolar abscess on fine needle aspiration because the lesion often recurs and usually requires surgical intervention (duct resection).

• In cases of silicone mastitis, silicone may migrate to axillary lymph nodes, leading to silicone lymphadenitis that clinically may mimic carcinoma.