M

Mammography: X-ray examination of the breast, usually involving two standard views of each side, namely medio-lateral oblique (side angled view) and cranio-caudal (top to bottom view). During this examination, the breast is gently compressed between two flat surfaces to obtain the images. Further specialised views can be taken to assess any specific abnormality found on standard views, eg lateral view, compression view, magnification view. Mammograms are scored on a scale of 1 to 5. A normal mammogram is M1; a benign opacity (such as a simple cyst (see entry), fibroadenoma (see entry)), or benign microcalcification (see entry) is M2; an indeterminate abnormality that is probably benign is scored M3; a lesion suspicious but not diagnostic of cancer is scored M4; and a diagnosis of cancer on radiological grounds is scored M5.

Mastalgia: breast pain or tenderness is a common benign condition, and can be either cyclical (worse as the menstrual cycle approaches), or non-cyclical (independent of the menstrual cycle). There is generally no specific underlying pathology, and is very rarely the symptom of any sinister condition. Breast pain may be associated with fibrocystic change (see entry), periductal mastitis (see entry), tense simple cysts (see entry), related to hormone replacement therapy use (see entry) or idiopathic (no established cause). Treatments relate to reduction of dietary saturated fats and caffeinated products, use of a well supporting bra, evening primrose oil or gamma linolenic acid for a defined period. Mastalgia refractory to these simple measures can be treated with bromocriptine, danazol or tamoxifen, which should be supervised by a breast specialist.

Mastectomy: removal of the breast usually to treat cancer. A mastectomy might be recommended if the cancer is large in relation to the size of the breast. More often, primary chemotherapy is used to attempt to shrink the cancer to enable breast conservation to be offered. This is successful in many cases. A mastectomy may also be offered if the tumour is widely multifocal, or if there is associated extensive ductal carcinoma in-situ (see entry). Mastectomy may also be indicated if there is local recurrence without a previous optimally treated breast. A total mastectomy aims to remove as much breast tissue as possible including the nipple and areolar. This is sometimes also called a simple mastectomy. A modified radical mastectomy usually refers to total mastectomy that includes axillary dissection (see entry). A radical mastectomy, that include resection of the underlying pectoralis muscle, are by and large an obsolete operation. Very rarely a radical mastectomy is indicated in a locally advanced cancer invading through into the muscle layer. A subcutaneous mastectomy aims to preserve the nipple and areolar and is often approached through a low incision in the inferior mammary crease. More microscopic breast tissue is usually left behind through this technique. A skin sparing mastectomy may be used in conjunction with immediate breast reconstruction (see entry) (see also prophylactic mastectomy). A delayed breast reconstruction may be performed in women who have previously had mastectomy without reconstruction. 

Metastasis: cancer that spreads outside the primary organ. In breast cancer, other organs or systems that are commonly affected are the bones, lungs and liver. Other sites include brain, ovary and skin. Patterns of metastatic spread can be complex, and treatment depends on previous therapy, affected sites, hormone and other receptor status.

Microcalcification: white spots of calcium visible on mammograms, scored by radiologists as benign, indeterminate or malignant. Most microcalcification is benign and requires no further action. Indeterminate microcalcification usually requires further assessment with specialised mammographic views (see mammography); some indeterminate microcalcification can be classified benign after further views but if the appearances remain indeterminate or suspicious, biopsy using a localisation technique within the mammogram machine under a local anaesthetic is usually recommended. Suspicious or malignant microcalcification require further views and imaging tests, followed by fine needle aspiration (see entry) or core cut biopsy (see entry) to establish a diagnosis to guide further management. See also DCIS entry.

Mondor's disease: is an eponym that describes a thrombo-phlebitis of the superficial veins of the breast. Superficial thrombo-phlebitis can affect any vein, and Mondor's disease describes this condition when it is confined to the skin of the breast. It is a self-limiting rare, benign condition, and in itself is not a risk factor for cancer. Initially, there may be some pain and redness in the area followed by the development of a cord like structure. This cord has also been described as a bowstring.  The aetiology of this condition is unknown. Most symptoms subside within a few weeks without any special medication. Symptoms relating to pain and inflammation are sometimes treated with a non-steroidal anti-inflammatory.

Multifocal cancer: the presence of cancer in more than one site within the breast. It is associated with a higher risk of local recurrence after breast conservation surgery, but usually does not impact on prognosis or survival. Multifocal cancer is a relative indication for a mastectomy in preference to breast conservation. See breast cancer, breast conservation surgery, and mastectomy entries.