Superficial, hard subcutaneous nodules in the upper outer quadrant of the female breast that resemble elephant skin should be considered as a possible filarial nodule. What are the causes of superficial, hard, elephant skin-like subcutaneous nodules in the female breast? Filariasis of the breast: Filariasis of the breast is a filarial granuloma that occurs when lymphatic vessels in the breast are blocked by parasitic bloodworms. The lymphatic ducts of the breasts of adult women are very rich, especially in pregnancy and breastfeeding, and under the action of sex hormones, the volume becomes larger and the lymphatic ducts expand, providing more opportunities for the parasitization of filariasis. The disease is characterized clinically by breast nodules, which are sometimes not easily distinguished from cancer. Therefore, the differential diagnosis of the disease is very important. Acute purulent mastitis: Acute mastitis is an acute purulent infection of the breast, commonly known as a “milk sore” or “canker sore”. Almost all patients are postpartum breastfeeding mothers, especially primiparous mothers. If the milk does not flow out of the breast and bacteria enter the breast from the broken nipple, inflammation may occur. In the initial stage, the patient has painful swelling of the breast, painful pressure on the affected area, red and hot skin on the surface, fever and other systemic symptoms, the inflammation continues to develop, the above symptoms are aggravated, at this time, the pain is pulsating, the patient may have chills, high fever, rapid pulse, etc., the affected axillary lymph nodes are often enlarged, and there is pressure pain, the white blood cell count is significantly higher and the nucleus is left shifted, the inflammatory mass often softens within a few days to form an abscess, superficial Superficial abscesses can be palpated and fluctuate, while deep abscesses need to be identified by puncture, and breast abscesses can be unicompartmental or expand into multicompartmental ones due to untimely drainage, or penetrate the skin from the outside, or abscesses can break into the milk ducts to form nipple overflow; several lesions can exist in the same breast at the same time and form multiple abscesses, and deep abscesses can penetrate deep into the loose tissue between the breast and the pectoral muscle, in addition to breaking out slowly. Severe acute mastitis can lead to necrosis of large pieces of breast tissue and even sepsis. Infiltrative breast cancer: Infiltrative breast cancer is a malignant tumor in which cancer cells have penetrated the basement membrane of breast ducts or lobules and invaded the interstitial space. The majority of invasive breast cancers are adenocarcinomas that originate in the parenchymal epithelial cells of the breast, especially in the lobular units of the terminal ducts of the breast. The etiology of breast cancer is multifactorial, with a family history of breast cancer being a high risk factor for the development of breast cancer, in addition to diet, fertility, hormonal imbalance, and mutations in related genes.