P

Paget's disease: A characteristic rash around the nipple areolar complex that is a cutaneous manifestation of underlying DCIS characterised by large cells in the basal layer, There is an association with invasive cancer that may be present elsewhere in the breast. Conventional treatment is with mastectomy, although central excision (including the nipple areolar complex) and radiotherapy may also be considered in suitable cases where there is no mammographic abnormality away from the subareolar area. Adjuvant therapy depends on the surgical pathology, see DCIS and invasive breast cancer entry.

Pathology: see entries for histology, histopathology and cytology.

Periductal mastitis: a cause for nipple discharge and central breast pain and / or inflammation. Periductal mastitis tends to occur in younger women compared to duct ectasia (see entry), and may be related to smoking. Has a higher tendency to cause inflammation and abscess formation, resulting in an indrawn nipple. Sometimes with inflammation around the nipple areolar complex.

Phyllodes: phyllodes tumours represent a range of breast tumours that span benign (the majority), to borderline (usually benign behavior but with a tendency for local recurrence) or frankly malignant. The risk of local recurrence for all categories is related to completeness of excision that should contain an acceptable surgical margin of normal breast tissue. Malignant phyllodes are associated with an increased risk of metastasis to distant sites through the blood rather than lymphatic systems, mostly to lung, liver and bone. The natural history of haematogenous rather than lymphatic spread makes axillary dissection usually unnecessary for malignant phyllodes tumours. The mainstay of treatment is wide surgical excision of the tumour, and the role of adjuvant treatments in malignant phyllodes tumour is less well defined than in breast cancer.

Primary chemotherapy: see chemotherapy entry.

Primary endocrine therapy: see endocrine therapy entry.

Prophylactic mastectomy: removal of both breasts, with or without breast reconstruction to reduce the risk of developing breast cancer in well women who are known to carry a breast cancer predisposing gene, or those calculated to have a high probability of carrying such a gene. The risk reduction is thought to be in the region of up to 90% in true at risk individuals. All women considering this risk reducing maneuver need to see a specialist breast surgeon and a geneticist.