Paget's Disease of the Breast and Bone
As you have alluded to, Paget's disease of bone (osteitis deformans) is a disease of uncertain etiology, which is characterized by excessive bone resorption accompanied by abnormal new bone formation. It is most often asymptomatic, but may involve pain, neurologic symptoms, increased calcium levels, fractures, or cardiovascular complications due to increased blood flow to abnormal bone. Treatment is not always required, but can range from NSAID's (aspirin, ibuprofen) to medicines to prevent bone resorption or even surgery to repair fractures.
Paget's disease of bone is medically unrelated to Paget's disease of the nipple, although it shares the same name. Paget's disease of the nipple is a rare form of breast cancer comprising 1 to 4% of all breast tumors. It is characterized by skin changes involving the nipple which resemble eczema. The relationship between the changes seen in the nipple and underlying breast cancer remains a matter of controversy. Many feel that the nipple involvement is secondary to migration of cells from an underlying cancer while others feel it is a separate process originating in the epidermis (superficial skin layer of the nipple). In 45% of cases, there is an associated palpable breast mass in the underlying breast while in most of the rest there are non invasive or invasive malignant cells. It is considered like other more common breast cancers when evaluating the extent of cancer. This work up includes a history and physical exam, mammogram, biopsy, and routine blood tests.
Traditionally, this disease has been treated by modified radical mastectomy. The rationale for this is the need to sacrifice the nipple and areola with conservation surgery anyway. Also, there is frequent, diffuse involvement of the ducts below the nipple, and frequent involvement with cancer at large distances from the nipple which may make conservation surgery more risky. In patients without a palpable mass and no evidence of tumor on mammography or disease confined to the subareolar area or nipple-areolar complex, it has been shown that excisional biopsy followed by radiation therapy to the whole breast is an acceptable alternative to mastectomy (which is reserved for local recurrences). Local recurrence rates and survival are similar to those seen with more common types of breast cancer when comparisons are made between similar stages (size of tumor and degree of spread).
Although breast cancer and Paget's disease of the nipple are not related to Paget's disease of bone, one important point remains. Approximately 1% of patients with Paget's disease of the bone develop a primary bone sarcoma in an area of their disease. This is a malignant tumor of the bone with an aggressive local growth pattern and a tendency to spread to distant sites. Most patients present with increasing pain in a localized area. Diagnosis can most often be made with plain x-rays and confirmed with a biopsy.
The following are some references for more information on Paget's disease of the nipple: