According to the American Congress of Obstetrics and Gynecology (ACOG) and the American Cancer Society (ACS), breast cancer accounts for 30% of all new cases of cancer in women.⁶ The lifetime risk of a woman having breast cancer is 1 in 8.^7,8 The Centers for Disease Control and Prevention (CDC) reports that breast cancer is the most common cancer in women (122.2/100,000).⁹ Because of this high incidence, it should always be considered in the differential diagnosis for breast masses and nipple discharge. Patients with breast masses or nipple discharge for whom clinical examination results, diagnostic images, and pathologic findings are all within the normal range can be reassured of benign breast conditions. 

Understanding breast anatomy and lymphatic drainage is key to an efficient and accurate physical examination and differential diagnosis. Overlying the pectoralis major muscle, breast tissue comprises layers of fat, glandular tissue, subcutaneous fat, and skin. Within the glands are ducts that drain into 5 major ducts behind the nipple. The breast tissue extends from the sternum to the mid axillary line, and from the clavicle to near the sixth rib at the infra-mammary fold. Most of the glandular tissue in the breast is in the upper outer quadrants, the tail of the breast, and the axilla. Stroma composes the glandular layer of the breast. Within the stoma are blood vessels, lymphatic vessels, fat, dense connective tissue and lobules, the endocrine component, and a system of ducts to carry milk to the nipple during lactation. Montgomery glands terminate in the periphery of the areola as Montgomery tubercles and function as sweat glands for lubrication to prevent cracking and infection, and mammary glands secrete milk.⁴ Lymphatic vessels, blood vessels, nerves, and ligaments all travel within the fat layer. Axillary nodes account for 75% of the lymphatic drainage in a stepwise fashion, which allows for staging of breast tumors by first evaluating the sentinel nodes.⁴ Collateral lymphatic drainage is medial, with parasternal nodes and more distal drainage to the supraclavicular and cervical nodes. 

Although the majority of breast masses are benign, malignant neoplasm should always be considered in patients who present with a breast mass.¹⁰ Physicians should pay attention to breast tenderness, unilateral or bilateral occurrences, nipple discharge, color of the nipple discharge, and whether discharge is spontaneous or expressed to assist in clinical diagnosis.^4,5 Laterality, location, size, mobility, tenderness, associated skin changes, and lymph nodes associated with the mass should be noted. 

Other possible diagnoses for a breast mass that may or may not be palpable and have histologic indications include radial scars and sclerosing adenosis. Radial scars often present as sclerosing lesions that manifest after the removal or biopsy of a breast mass.¹¹ These scars may be seen on mammography and excised if malignant neoplasm is suspected. Sclerosing adenosis presents as a tender or nontender fibrous, lobular mass. There is a 1.5 to 2 times increased risk of cancer developing with this finding.¹ No treatment is necessary for patients with this condition. 

The most common cause of a tender, bilateral, mobile, well-circumscribed, symmetric breast mass is fibrocystic breast changes.^4,5 The lifetime prevalence of fibrocystic breast changes in women is 70% to 90%.⁴ Fibrocystic breast changes most commonly present in the fifth decade of life as a tender breast mass, exacerbated during the second half of the menstrual cycle.⁴ Woman with fibrocystic breast changes often have mastalgia during the second half of their menstrual cycle that resolves with menstruation,⁴ and their breasts are often tender and nodular.⁴ Ultrasonographic imaging of the breast in patients with fibrocystic breast changes will reveal a fluid-filled cyst, which can be simple or complex. Simple cysts are typically benign, and complex cysts may require ultrasound-guided needle aspiration, core-needle biopsy, or surgical excision.⁴ Ultrasonography with needle aspiration of nonbloody fluid can be useful in confirming the findings.⁴ These cysts may grow to a size of 2 to 10 cm, and therapeutic needle aspiration may be recommended if discomfort persists.⁴ If the fluid is bloody or turbid, it should be sent for cytologic evaluation. If no fluid is obtained, further evaluation with ultrasonography or surgical excision should be considered.⁴ Recurrence of an aspirated cyst requires reevaluation. Nonsteroidal anti-inflammatory drugs (NSAIDs) may be recommended to relieve breast pain. 

The differential diagnosis for a tender, unilateral breast mass includes breast abscess, galactocele, mastitis, lymph node, Mondor syndrome, and hematoma. The first 3 conditions are commonly associated with breastfeeding, and hematoma may be iatrogenic. Breast abscesses typically occur around the time of lactation in women who are breastfeeding, but they can also occur in postmenopausal women.^4,5 Common symptoms in women with breast abscesses include fever, erythema, edema, localized warmth, and unilateral nipple discharge.¹⁰ Complete blood cell count will reveal leukocytosis, and ultrasonographic images will show a complex cystic mass.^4,5,10 Antibiotic therapy, typically trimethoprim/sulfamethoxazole or cephalexin, is recommended.^4,5 If the symptoms do not resolve during the course of antibiotics, inflammatory breast cancer should be considered in the differential diagnosis, and histologic examination is recommended for confirmation. With a persisting or recurring abscess, ultrasound-guided aspiration, incision with drainage, or surgical excision may be recommended.⁴ 

A galactocele is a cystic collection of fluid, typically in an obstructed milk duct, that can occur while breastfeeding or during pregnancy at a gestational age of 20 weeks or older.¹⁰ Symptoms include a tender, unilateral, irregular, soft breast mass. The patient may not feel ill, may be afebrile, and will have a normal white blood cell count.^4,5 Diagnosis of a galactocele is made using ultrasonography, ultrasound-guided aspiration, or fine-needle aspiration. The fluid consists of breast milk and may be green if it has been present for an extended period.⁴ 

Mastitis occurs during breastfeeding or shortly after weaning, secondary to nipple trauma.^1,10 The patient typically feels ill, fatigued, and weak and has a painful, erythematous breast mass involving a particular quadrant of the breast.^1,10 Symptoms include a hot, erythematous, edematous quadrant of the breast with or without lymphadenopathy. Bacterial infections are typically the source of mastitis.^1,4,10 The most common inciting bacteria is Staphylococcus aureus, but group B Streptococcus, Escherichia coli, or Bacteroides may also be present.⁵ Management of mastitis consists of warm compresses on the breast and dicloxacillin or cephalexin (or clindamycin or erythromycin if the patient is allergic to penicillin). If methicillin-resistant S aureus is suspected, then double-strength trimethoprim/sulfamethoxazole or clindamycin should be prescribed. Mastitis may result in an abscess, in which case incision and drainage is recommended.⁴ Mastitis can progress to a systemic infection, leading to sepsis and requiring hospitalization and intravenous antibiotics. If mastitis does not improve during the course of antibiotic therapy or is noted in a postmenopausal woman, cancer should be considered. 

A lymph node may present as a breast mass, most commonly located in the upper-outer quadrant and tail of the breast or the axilla. It can also be found parasternally.⁴ Ultrasonography with or without ultrasound-guided needle biopsy or core-needle biopsy may be used to confirm the diagnosis. Depending on pathologic results, mammography or surgical excision may be recommended.⁴ 

Mondor disease can present as a painful breast mass with erythema resulting from thrombophlebitis of 1 of 3 veins: thoracoepigastric, lateral thoracic, or superior epigastric.⁴ Symptoms include a tender, warm, vertical, nodular cord in the lateral segment of the breast along the course of the infected vessel. Ultrasonography is used to confirm inflammation of the vein. Management includes warm compresses and NSAIDs for symptom relief, as this condition often resolves spontaneously. 

An iatrogenic cause of a breast mass is a hematoma, which may present after performing diagnostic procedures or may be a result of trauma.¹² A thorough patient history may elucidate this diagnosis and the cause of the mass. Palpation will reveal a tender, firm, possibly irregular mass with or without skin ecchymosis.¹³ Management consists of symptom relief using cold compresses. 

A benign, palpable, nontender breast mass can have several different presenting characteristics. Fibroadenomas or lipomas are the most common cause of a nontender unilateral mass without nipple discharge.^2,4,5 Fibroadenomas are benign, solid masses of stromal overgrowth. In the breast, they may be bilateral or unilateral and, depending on the size, may be tender.^2,4,5 Fibroadenomas are most common in women aged 20 to 35 years who are hormonally stimulated, and they may increase in size during pregnancy and decrease after menopause.^2,4,5 In women without a family history of breast cancer, fibroadenomas do not change the relative risk of breast cancer.^2,4,5 Additional lesions may be found in up to 15% of women with fibroadenomas.^2,4,5 Ultrasonography can aid in the diagnosis of fibroadenomas with a specific finding of a hypoechoic mass with lobulated margin that may have an echogenic halo.^2,4,5 If ultrasonographic imaging is not confirmatory, a core-needle biopsy is recommended. Management can include surgical excision if the mass is painful, if the mass is rapidly enlarging, if it is larger than 5 cm, or if the patient desires removal. Fibroadenomas less than 3 cm should be reevaluated with a clinical examination and ultrasonography every 6 months for 2 years to ensure that the size remains stable.^2,4,5 

A rapidly growing solid mass that resembles a fibroadenoma may be a phyllodes tumor. Phyllodes tumors are rare (<1% of benign breast neoplasms) and occur at a median age of 40 years. They can be classified as benign, intermediate, or malignant.¹⁴ Treatment for patients with phyllodes tumor is wide local incision with 1-cm margins. Tumors with malignant classification can metastasize but usually do not metastasize to lymph nodes, so lymph node staging is not required. Recurrence in malignant types is 36%, which is more common than in benign types (8%).¹⁴ 

Lipomas are smooth, well-circumscribed, superficial masses of varying size. Diagnosis of a lipoma is confirmed on ultrasonographic imaging demonstrating fatty tissue.⁴ A ultrasound-guided or core-needle biopsy may be required. No management or follow-up is necessary unless the patient is symptomatic. If patients with lipomas are symptomatic, they may present with an enlarging, nontender mass.⁴ 

Fat necrosis after surgery or trauma with a resultant scar may be confused with neoplasm because it forms a palpable mass on examination. Diagnosis is confirmed with mammographic or ultrasonographic imaging showing a fluid-filled cyst along with needle aspiration of oily fluid. Surgical excision is not indicated.¹⁵ 

Hormonal changes in the perimenopausal period with anovulatory cycles and decreasing estrogen levels result in cyclic mastalgia. Mastalgia that does not vary in relationship to the menstrual cycle is considered noncyclic and may be related to causes such as cysts, trauma (associated with hematoma), Mondor syndrome, or cancer.² Extramammary sources of mastalgia include costochondritis, myofascial strain, cervical radiculopathy, chest wall trauma, rib fractures, reflux, and angina.² When examining a patient with mastalgia, a thorough history should be taken, and a physical examination should be performed. Diagnostic evaluation using mammography or ultrasonography, reexamination 6 weeks after presentation, and management with osteopathic manipulative treatment and NSAID for pain relief should be considered.⁵ 

The physical examination of a patient presenting with nipple discharge should include palpation of the nipple and identification of the discharge, noting its consistency and color. Benign or physiologic nipple discharge may be bilateral or unilateral and expressed or spontaneous. The discharge may be milky, bloody, white, or green to black in color and can arise from multiple ducts.^2,4,5 During their reproductive years, 50% to 80% of women will have nipple discharge.¹ Recommended management includes decreasing nipple stimulation.⁴ 

Galactorrhea is nipple discharge that is bilateral, abundant, spontaneous, and milky. It is found in the setting of hormonal changes and is an endocrine disease, not a breast disorder.^{2,4,5,11,15-18} This type of discharge is typically associated with menstrual changes, such as oligomenorrhea or amenorrhea.^{2,4,5,11,15-18} When a patient presents with both menstrual changes and nipple discharge, a pregnancy test should be initially performed. If the results are negative, the patient's medications should be reviewed and thyroid-stimulating hormone should be checked, as medications may interfere with metabolism and secretion of hormones.⁴ The patient's serum prolactin level can be helpful to determine whether this discharge is from a prolactinoma, which is a tumor of the anterior pituitary resulting in increased secretion of stimulating hormones and galactorrhea and menstrual changes.⁴ When the prolactin level is elevated, magnetic resonance imaging of the pituitary is recommended. Bromocriptine can relieve symptoms and decrease tumor size in patients with galactorrhea. Spontaneous bilateral nipple discharge may be iatrogenic from medication or herbal supplements. 

Bloody or serous spontaneous nipple discharge from a single duct is pathologic, most commonly associated with an intraductal papilloma, a solitary tumor that grows from the wall of the lactiferous ducts and is usually located anterior to the areola.^2,4,5 Physical examination will reveal bloody or serous nipple discharge without a palpable mass. Mammography, ductography, or magnetic resonance imaging may be useful in the diagnosis of intraductal papilloma. Management of intraductal papilloma entails surgical excision of the duct. 

An osteopathic structural examination can be a useful component of a complete diagnostic evaluation of a suspected breast condition, as it can aid in distinguishing somatic dysfunction from visceral dysfunction in the chest. It is important to palpate the posterior thorax for somatic dysfunction, including viscerosomatic reflexes in patients with symptoms relating to the chest. The sympathetic viscerosomatic reflex distribution in the breast tissue correlates to the intercostal nerves that innervate it (T4-6). Of note, these spinal segments overlap with other sympathetic viscerosomatic regions of the head and neck (T1-4), heart (T1-5), lungs (T1-5), esophagus (T-9), and upper gastrointestinal tract (T5-9).^19,20 

During the palpatory examination, the physician should also be aware of the regional Chapman reflex points, which are thought to be reflections of visceral pathology within the fascia (ie, viscerosomatic reflex). Chapman reflex points are defined as fascial tissue texture abnormalities, possibly resulting from lymphatic congestion. They have been described as ganglioform contractions that are edematous, ridgelike, ropy, fibrospongy, or shotty and are of varying size and tenderness.²¹ 

The differential diagnosis for somatic dysfunction of the anterior thorax may include rib dysfunction or myofascial strain. Rib dysfunction may be respiratory or mechanical in nature. During rib palpation, the range of motion with deep respiration, rib tenderness, costal cartilage, costochondral joints, and chondrosternal joints, as well as rib prominence or retraction, should be noted. Myofascial strain of the muscles listed previously may be secondary to posture or activity and can present with tenderness in the muscle belly or attachment site, muscle hypertonicity, or restricted range of motion of the joints it spans. Adjacent regions should be assessed, particularly the shoulder girdle and the upper extremities, as these regions may be implicated in the cause of the presenting symptoms or may be secondarily affected by them. 

Physicians should take a holistic approach to evaluating patients, including taking note of their posture, habits, and body mechanics, which can produce dysfunctional patterns of stabalization.²² A number of techniques can target somatic dysfunction found during the osteopathic structural examination, including myofascial release of the anterior and posterior axillary fold, muscle energy for rib dysfunctions, rib raising for generalized rib restriction, and balanced ligamentous approach for thoracic inlet restriction. It is advisable for physicians to be familiar with these manipulative treatment options and understand their indications and contraindications. 

Palpable breast masses or nipple discharge are common symptoms in women presenting in the clinical setting,^1,2 and a holistic approach to the evaluation and differential diagnosis formation should be taken. It may also be useful to perform an osteopathic structural examination to distinguish somatic dysfunction from a visceral origin. Different breast conditions have unique presentations and approaches to clinical assessment. Effective evaluation and management is important in establishing the diagnosis and management of the different palpable benign breast masses and nipple discharge.