What and where are the lymph nodes?
The lymph nodes are bean-like organs located mainly in the neck, armpits, groin, chest and abdominal cavity. They are linked by the lymphatic vessels, which deliver the fluid called the lymph from around the cells to them. The lymph nodes filter microbes, cancerous cells and other foreign particles from the lymph. Together with the white blood cells, tonsils, thymus, spleen and bone marrow, they form the body’s immune system.
Swollen lymph nodes appear as painful or painless lumps in the neck, armpits or groin. On a CT or MR image, they appear or as white round shadows.
In healthy adults, the lymph nodes vary from few millimeters to about 2 cm in size and are usually not palpable or visible–except in very slim persons [5,9,12]. Some healthy adults, especially those who walk barefoot, can have persistent small (<1 cm), firm and movable nodes in the groin as a result of recurrent “insults” in the legs .
In healthy older children and some young adults–but not in small children or infants–small, firm “shotty” lymph nodes in the neck and armpits can often be palpated as a result of recurrent viral infections [5,65].
Swollen Lymph Nodes (Lymphadenopathy) — Causes, Symptoms and Signs
The medical term for swollen (enlarged) or abnormally shaped lymph nodes is lymphadenopathy and for infected nodes lymphadenitis.
What do swollen lymph nodes feel and look like?
Pain. In infections and insect bites, lymph nodes tend to be tender or painful, while in autoimmune diseases and cancers tend to be painless.
Palpability and size. Swollen lymph nodes in the neck, armpits and groin are palpable or visible, but those within the chest or abdominal cavity are not. Nodes are generally considered to be normal if they are up to 1 cm in diameter; however, some authors suggest the nodes in the elbows larger than 0.5 cm or the nodes in the groin larger than 1.5 cm should be considered abnormal . Sometimes, a swollen lymph node can be bigger than 2 inches. Enlarged nodes usually appear as lumps with well-defined borders and are covered by normal or reddened skin.
Consistency and mobility. In infections, the lymph nodes tend to be soft and mobile under the fingers, while in cancers they tend to be hard, grouped together and fixed.
Swelling duration. In insect bites and acute infections, the lymph nodes can remain swollen for few weeks, in chronic infections, autoimmune diseases and cancers for several months or years and in hereditary storage diseases lifelong. The lymph node enlargement that persists for more than 3-4 weeks should be checked for cancer.
Unilateral, Bilateral, Right and Left Side Lymph Node Enlargement
Unilateral lymph node enlargement (only on the right or only on the left side) is typical for localized infections (cellulitis, cat-scratch disease), insect bites and metastases of solid cancers (breast, lung, gastrointestinal, etc.).
Except for the enlargement of the left supraclavicular lymph nodes, which is very suspicious for the chest or abdominal cancers, the side of the enlarged lymph node does not tell much about the underlying cause.
Bilateral lymph node enlargement (on both sides) is typical for systemic infections (infectious mononucleosis, HIV/AIDS), autoimmune diseases (rheumatoid arthritis, systemic lupus erythematosus), adverse reactions to drugs, lymphoma, blood cancers (leukemia) and storage diseases.
Swollen Lymph Nodes and Enlarged Spleen
Swollen lymph nodes and an enlarged spleen (splenomegaly) can be present in infectious mononucleosis, systemic lupus erythematosus, cat-scratch disease, sarcoidosis, toxoplasmosis, lymphoma or leukemia [45-s.132].
Swollen Lymph Nodes and Cancer
Only about 1% of the enlarged lymph nodes that can be palpated by the fingers are caused by cancers; in most other cases, they are caused by acute infections . Risk factors that speak for cancer as a cause of enlarged lymph nodes [1,65,80]:
- Age >40
- Exposure to risk factors: smoking (lung and stomach cancer), alcoholism (liver and pancreatic cancer), the sun (skin cancer), radiation
- The location of lymph nodes above the clavicles (supraclavicular nodes)
- Enlarged (>2 cm), firm, fixed and painless lymph nodes, often in more than one body area present for more than 4 weeks and increasing with time
Chart 1. Swollen Lymph Nodes – Common Characteristics
|Local infections||Painful, soft, unilateral||Localized limb redness or swelling|
|Systemic infections||Painless, soft, bilateral||Fever, (a sore throat)|
|Insect/snake bites||Painful, soft, unilateral||Visible bite, limb swelling|
|Autoimmune diseases*||Painless, soft, bilateral||Rash, swollen joints|
|Adverse reactions to drugs||Painless, soft, bilateral||Rash, fever, hives, itch|
|Solid cancers||Painless, hard, unilateral||Unintentional weight loss, anorexia|
|Lymphoma, leukemia||Painless, hard, bilateral||Low-grade fever, itch|
|Storage diseases||Painless, soft, bilateral||Enlarged liver/spleen, in childhood|
Chart 1 legend: * Autoimmune diseases = rheumatoid arthritis, systemic lupus erythematosus, Sjögren’s syndrome, etc. Possible exceptions: infections with painless nodes, rheumatoid arthritis or cancer with painful nodes, unilateral instead of bilateral enlargement.
NOTE: The following does NOT cause lymph node enlargement: physical exercise, dehydration, cold or warm weather, anxiety, pregnancy, deodorants and allergic reactions to foods or seasonal allergies.
Chart 2. Other Body Lumps and Bumps
Swollen Lymph Nodes by the Body Region:
1. Generalized lymphadenopathy
2. Under the jaw – submandibular nodes
3. At the front of the neck – anterior cervical nodes
4. On the sides of the neck – posterior cervical nodes
5. Above the clavicles – supraclavicular nodes
6. In front of the ears – preauricular nodes
7. Behind the ears – retroauricular nodes
8. At the back of the neck- occipital nodes
9. In the armpits – axillary nodes
10. In the chest – mediastinal and hilar nodes
11. Abdominal nodes
12. In the groin – inguinal nodes
13. In the elbow – epitrochlear nodes
14. Behind the knees – popliteal nodes
1. Generalized Lymphadenopathy
Generalized lymphadenopathy refers to swollen lymph nodes in at least 2 distinct body regions, for example, in the neck and armpits, or in the armpits, chest and groin.
- Viral infections:
- In adolescents and young adults: infectious mononucleosis (caused by Epstein-Barr virus; symmetrical, enlarged spleen [in 50%], low-grade fever, a sore throat, red rash) [13,33], hepatitis A, B and C, cytomegalovirus (CMV, bilateral) , HIV/AIDS (bilateral, nontender; rash, fatigue, muscle pain) [2,13]
- Dengue fever (mosquito-borne) 
- Bacterial infections: typhoid fever (in India, Indonesia, South America) [9,13], extrapulmonary tuberculosis (usually nontender, bilateral) , bacterial endocarditis (in intravenous drug abuse) [2,12], African trypanosomiasis or sleeping sickness , American trypanosomiasis or Chagas disease , tularemia (tender nodes, after a tick bite) [9,67], Lyme disease (after a tick bite) , secondary syphilis, plague (tender, bilateral, in southern US) 
- Fungal infections: ringworm of the scalp (Tinea capitis) , cryptococcosis 
- Parasitic infestations: lymphatic filariasis
- Autoimmune disorders (bilaterally enlarged nodes): rheumatoid arthritis, systemic lupus erythematosus or SLE (facial rash), Sjögren’s syndrome, sarcoidosis (a dry cough, difficulty breathing) , dermatomyositis [2,9,14]
- Adverse reactions to medicines (with rash, fever, hives and itch): allopurinol, antibiotics (cephalosporins, isoniazid, penicillins, sulfonamides, trimethoprim/sulfamethoxazole), atenolol, captopril, carbamazepine, gold, hydantoin, hydralazine, phenylbutazone, phenytoin, primidone, pyrimethamine, quinidine, sulindac [1,2,13]
- Cancers: non-Hodgkin lymphoma, chronic leukemia (enlarged liver and spleen) [4,10,51,52], Kaposi’s sarcoma (in HIV/AIDS) [48,60]
- In children:
- Lice infestation 
- Viral infections: roseola infantum, chicken pox, rubella, measles, adenovirus infection
- Infantile papular acrodermatitis or Gianotti-Crosti syndrome 
- Anemia: sickle cell anemia, thalassemia 
- Acute leukemia (fatigue, easy bruising or bleeding, low-grade fever, enlarged liver and spleen) [4,10,51,52]
- Genetic storage disease: Gaucher’s disease, Niemann-Pick disease, Fabry’s disease, Tangier disease 
- Other causes of generalized lymphadenopathy [1,5]:
- Hyperthyroidism (Grave’s disease), adrenal insufficiency (Addison’s disease) 
- Serum sickness after infusion of plasma or injection of drugs (fever, hives, itch) [13,20]
- Adult-onset Still’s disease (a severe form of juvenile rheumatoid arthritis) 
- Eosinophilic granuloma (Histiocytosis X, Langerhans cell histiocytosis) 
- Castleman’s disease (overgrowth of the lymphatic tissue in the lymph nodes and spleen) 
- Severe familial hypertriglyceridemia (high triglyceride levels) 
- Primary biliary cirrhosis
- Graft versus host disease (after bone marrow transplantation) 
Benign reactive lymphadenopathy (lymphoid hyperplasia) refers to mild lymph node enlargement–mostly in the neck and armpits–as a reaction to various substances in the environment, systemic infections (infectious mononucleosis) or autoimmune disorders (systemic lupus erythematosus) [53,71]. It is common in older children and young adults, in which the cause is usually not apparent [53,71]. The lymph nodes are enlarged because of the reactive overgrowth of the lymphocytes in them, but the nodes themselves are not infected or damaged in any way.
Persistent generalized lymphadenopathy refers to chronic lymph node enlargement in at least two distinct body areas that persist for at least 3 months for no apparent reason. It can appear in individuals with autoimmune disorders ( systemic lupus erythematosus, rheumatoid arthritis), infectious mononucleosis, CMV infection, tuberculosis, atypical mycobacteria infection, cat-scratch disease, toxoplasmosis, HIV/AIDS or syphilis [45,78,79] but the cause often can not be identified .
2. Submandibular Nodes (Under the Jaw)
Submandibular nodes drain the skin on the cheeks, nose, lips, tongue and mouth [1,2,15,25].
Picture 1. Enlargement of the submandibular gland in a woman with non-Hodgkin lymphoma (Samuel Freire da Silva, MD, Atlasdermatologico.com.br)
Causes of enlargement [1,2]:
- Infections of the facial skin, tooth abscess, herpetic gingivostomatitis, sinusitis; in children: an infection with atypical Mycobacteria or Mycobacterium avium complex 
- Drugs: phenytoin (long-term use) 
- Cancers in the mouth , lymphoma (Picture 1), leukemia
Submental Nodes (Under the Chin)
Submental nodes drain the tip of the tongue, mouth floor, skin of the chin and the medial third of the lower lip . They can be enlarged in infections of the skin on the chin and under the jaw, mouth floor, nasal cavity and paranasal sinuses (sinusitis), in sarcoidosis [34,80] and cancers of the lower lip and the front portion of the mouth floor .
Tonsillar Nodes (Under the Jaw Angle)
Tonsillar nodes drain the tonsils; they can be enlarged in strep throat (bacterial pharyngitis).
3. Anterior Cervical Nodes (In Front of the Neck)
Anterior cervical nodes are located on both sides of the throat from the jaw angle to the clavicle. They drain the skin on the neck, the larynx (voice box), nasal part of the throat, nasal cavity, thyroid and parotid gland and the auricle [12,15,25,26,27].
Picture 2. A man with enlarged lymph nodes on both sides of the neck (and probably under the jaw) and rash due to infectious mononucleosis (Wikimedia, Creative Commons license)
Causes of enlargement [1,2]:
- Viral infections (nodes: usually bilateral, painless, no redness) [2,4,49,50,65]: common cold or influenza, pharyngitis, acute bronchitis, oral herpes; cytomegalovirus, infectious mononucleosis (in adolescents, low-grade fever, a sore throat, rash; Picture 2) [7,8,9,33], HIV/AIDS 
- Bacterial infections (nodes: usually unilateral, painless): strep throat, impetigo, cat-scratch disease, tularemia (after drinking contaminated water) , extrapulmonary tuberculosis (large, nontender nodes–scrofula–that may drain spontaneously) [4,9,13,69,74], brucellosis (after ingestion of raw dairy) , atypical Mycobacteria (oozing nodes) , an infection of the middle ear (otitis media)
- Parasitic infections: toxoplasmosis (after eating undercooked meat or food contaminated by cat feces) [12,73]
- Thyroiditis, thyroid cancer 
- Drugs: mephenytoin 
- Skin cancers of the head and neck, cancer of the mouth, pharynx or larynx, lymphoma, acute or chronic leukemia [10,51,52,82]
- Sarcoidosis [34,37]
- Amyloidosis [13,62]
- Kimura’s disease (painless, chronic, unknown cause) 
- In children: Kawasaki’s disease (unilateral, fever, red rash on the hands and feet, red tongue) [30,65]
Other causes of lumps in the front of the neck include ingrown hair, epidermoid cyst, boil, a muscle knot in the wry neck or torticollis, thyroid conditions (nodules, goiter, thyroiditis, tumors), lipoma, carotid body aneurysm, venous aneurysm and genetic conditions (cervical rib, branchial cleft cyst, laryngocele, thyroglossal duct, hemangioma, cystic hygroma).
4. Posterior Cervical Nodes (At the Sides of the Neck)
Posterior cervical nodes are located at the sides of the neck along the line from behind the ear to the clavicle . They drain the skin of the scalp, neck, the thumb aspect of the arm, upper chest and chest cavity .
Picture 3. Tick bite behind the ear and swollen node in the neck few inches below it (Wikimedia, Creative Commons license)
Causes of enlargement:
- Skin infections of the head, neck and upper chest
- Viral infections (nodes: bilateral, painless, no redness) pharyngitis, infectious mononucleosis, rubella [9,27,33,53,65]
- Bacterial infections: extrapulmonary tuberculosis (nodes: usually nontender) [15,69,74], African trypanosomiasis or sleeping sickness 
- Cancers of the skin at the back of the head and neck, pharyngeal cancer, lymphoma (especially Hodgkin’s) [15,82]
- Kikuchi disease or histiocytic necrotizing lymphadenitis (rare; painless nodes, fever) [28,29]
Other causes of lumps on the sides of the neck include boil, lipoma, neuroma and muscle knots in wry neck .
5. Supraclavicular Nodes (Above the Clavicle)
- Right: the space in the chest between the lungs (mediastinum), esophagus, lungs
- Left: gastrointestinal and genitourinary tract
- Both: head, neck, arms, chest wall
Causes of enlargement [1,2]:
- Either right or left node alone: infections, such as extrapulmonary tuberculosis , toxoplasmosis, histoplasmosis, coccidioidomycosis (southern US) ; thyroid and upper esophageal cancer , advanced breast cancer [10,32]
- Left supraclavicular node (“Virchow’s node,” Troisier’s sign, Picture 4) as a single enlarged node is strongly suggestive for abdominal or pelvic cancer (most commonly stomach [gastric], but also gallbladder, kidney, pancreatic, colorectal, ovarian, testicular or prostatic cancer) or cancer in the thorax [5,12,83].
- A right supraclavicular node as a single enlarged node is suggestive for lung, esophagus, mediastinum or abdominal cancers [5,13,16].
- Bilateral enlargement of supraclavicular nodes (on both sides) can occur in extrapulmonary tuberculosis , sarcoidosis  or lymphoma.
Other causes of lumps below the clavicles include lipoma.
Infraclavicular Nodes (Below the Clavicle)
Infraclavicular lymph nodes drain the upper portions of the breasts . They can be enlarged in advanced breast cancer  and non-Hodgkin lymphoma . Other causes of lumps below the clavicles include lipoma.
6. Preauricular Nodes (In Front of the Ears)
Preauricular nodes are located in front of the ear at the level of the ear’s tragus . They drain the skin from the temples and front of the head, the front side of the external ear, eyelids and the conjunctiva of the eye [2,12,13,15,25].
Causes of enlargement [1,2,15]:
- Eye infections: conjunctivitis caused by viral infections, keratoconjunctivitis, cat-scratch disease , tularemia , ophthalmic herpes zoster, trachoma, tuberculosis, gonorrhea, chancre or sporotrichosis. An inflammation of the eye’s conjunctiva in combination with enlarged lymph nodes in front of the ear on one side and fever is called Parinaud’s oculoglandular syndrome .
- Infection of the middle ear (otitis media) or parotid gland , erysipelas
- Cancers of the head (rarely) 
Other causes of lumps in the front of the ear include parotid gland conditions: infection (mumps), inflammation (sialadenitis) or tumors; tooth abscess, erysipelas (red swelling) and–in children–hemangioma, cystic hygroma and branchial cleft cyst .
7. Retroauricular Nodes (Behind the Ears)
Retroauricular (postauricular) nodes are located behind the ear. They drain the back side of the auricle and external ear canal, temples and the top of the head [15,25].
Causes of enlargement (mainly in children):
- Infections of the outer ear, scalp ringworm, parvovirus infection, rubella [9,15]
- Seborrheic dermatitis 
- Spread of cancer from the nasal part of the pharynx 
Other causes of lumps behind the ear include boil, mastoiditis and lipoma.
8. Occipital Nodes (At the Bottom Back of the Head)
Occipital nodes are located at the base of the skull at the back of the head. They drain the scalp at the back of the head [1,15,25].
Causes of enlargement [1,2,15]:
- Local infections: staphylococcal folliculitis (furuncles), fungal infections of the scalp (Tinea capitis, ringworm) 
- Viral infections: parvovirus infection, rubella , measles, roseola infantum
- Seborrheic dermatitis 
- Pediculosis (lice)
- Toxoplasmosis 
- Cancers (rarely): lymphoma, metastases from distant tumors 
Other causes of bumps and lumps at the nape of the neck include ingrown hair, boil (furuncle), keloid, bone spurs, lipoma, epidermoid cyst, skin cancer and–in children–hemangioma and cystic hygroma .
9. Axillary Nodes (In the Armpits)
Axillary nodes are located in the armpits. They drain the lateral portions of the breasts and chest wall, the abdominal wall above the belly button, arm, hand and the little, ring and middle finger .
Causes of swollen lymph nodes in ONE armpit [1,2,4]:
- Infections in the arm:
- Cat-scratch disease (painful or painless armpit nodes, scratch in the arm) [6,9,13]
- Cellulitis (arm swelling and redness) or lymphangitis (red streaks traveling along the arm)
- Varicella-zoster infection (shingles – pain followed by burning rash) 
- Other infections in the arm: erysipeloid (in fishermen and meat handlers) , sporotrichosis, tularemia (after a rabbit bite) , brucellosis (after contact with cows or sheep) , leishmaniasis or Kala Azar (Africa, Mediterranean, China, South America) [12,13]
- Infection in the armpits:
- Hidradenitis suppurativa (armpit pain, oozing abscesses, red skin)
- Infection of the breast (mastitis)
- HIV/AIDS (nontender) 
- Spider, scorpion or snake bite in the arm (painful node enlargement; lymphangitis – red streaks leading from a bite to the armpit) 
- Sarcoidosis 
- Cancers: breast cancer (armpit nodes may be palpable earlier than a tumor in the breast), skin cancer, leukemia, soft tissue/Kaposi’s sarcoma [1,48]
- Recent vaccination in the arm, such as BCG vaccine against tuberculosis
Causes of swollen lymph nodes in BOTH armpits [1,2,4,14]:
- Infectious mononucleosis (tender or not) 
- Autoimmune diseases: rheumatoid arthritis, systemic lupus erythematosus, Sjögren’s syndrome, scleroderma, dermatomyositis, psoriasis, sarcoidosis
- Lymphoma (painless nodes, but alcohol drinking can trigger pain), leukemia
- Silicon breast implants
- Diabetic mastopathy
- Infections: tuberculosis (extrapulmonary) , toxoplasmosis (after an ingestion of parasites by cat feces) , tularemia (after a rabbit bite) , secondary syphilis, leprosy
Other causes of lumps in the armpits include ingrown hair, boil (furuncle), lipoma and hidradenitis suppurativa.
10. Mediastinal and Hilar Nodes (In the Chest)
Mediastinal nodes are located in the chest, between the lungs and the hilar nodes at the entrance of the bronchi into the lungs (hilum) . They drain the lungs, pleura, heart, pericardium, thymus, esophagus, trachea and bronchi .
Picture 5. A CT image shows enlarged right mediastinal lymph nodes (arrow) due to a spread of cervical cancer in a 47-years old woman (Lung India, Creative Commons license).
Causes of enlarged mediastinal nodes: chronic obstructive pulmonary disease (COPD) , mediastinal tumors, Castleman’s disease 
pleural mesothelioma 
Causes of enlarged hilar lymph nodes on ONE side:
- Bacterial pneumonia [46,47]
- Interstitial lung disease 
- Pulmonary tuberculosis (unilateral in 2/3 cases) [9,10,47,74]
- Sarcoidosis 
- Tumors: lymphoma , metastases of bronchogenic carcinoma (lung cancer) [2,39,40], Kaposi’s sarcoma (common in HIV/AIDS) [47,48] and cancers of the esophagus, stomach, pancreas, testes, breast, and colon
- Picture 6. Sarcoidosis [10,34,37,39] with bilateral hilar node enlargement (an X-ray image) (Radiopedia, Creative Commons license)
- Infections [9,39,40]: fungal lung infections: histoplasmosis, coccidioidomycosis; atypical (mycoplasma) pneumonia, tularemia, HIV/AIDS , tuberculosis (bilateral in 1/3 cases) 
- Hypersensitive pneumonitis or extrinsic allergic alveolitis, for example, bird fancier’s lung and farmer’s lung 
- Inorganic dust diseases: asbestosis, berylliosis, coal worker pneumoconiosis, silicosis [38,40]
- Cystic fibrosis in adults 
- Cancers, such as lymphoma and bronchogenic carcinoma only rarely present with bilateral hilar node enlargement [39,40]
Symptoms commonly associated with enlarged hilar nodes include a dry cough, coughing up blood, wheezing, difficulty swallowing (dysphagia), swelling of the face on one side (superior vena cava syndrome) .
Other causes of abnormal rounded masses in the mediastinum (visible on X-ray, CT or MRI) include enlarged pulmonary arteries (in pulmonary hypertension), hiatal hernia, cysts, lipoma, thymoma and teratoma.
11. Abdominal Nodes
Abdominal nodes drain the abdominal organs (stomach, liver, gallbladder, pancreas, kidneys, intestine) and pelvic organs (bladder, prostate, testicles, uterus, Fallopian tubes, ovaries) .
- Viral infections: mesenteric adenitis, infectious mononucleosis 
- Tuberculosis (extrapulmonary) [9,69]
- Crohn’s disease , ulcerative colitis
- Abdominal cancers, intestinal lymphoma
- Picture 7. Hodgkin lymphoma causing the enlargement of the lymph nodes in the abdomen (a CT image of mesenteric lymphadenopathy) (Radiopedia, Creative Commons license)
Rarely, an abdominal or pelvic cancer can cause the enlargement of the abdominal lymph nodes that cause visible lumps near the belly button (“the node of Sister Mary Joseph”) [5,13].
Common associated symptoms include constipation, abdominal pain and lower back pain .
Other causes of rounded masses in the abdomen (visible on X-ray, CT or MRI) include lipoma, fibroma and cancers.
12. Inguinal Nodes (In the Groin)
Inguinal nodes are located in the groin on the either side of the genitalia.
- Horizontal (upper) group: lower abdominal wall, retroperitoneal space (around the kidneys), penis and scrotum skin, anal canal, vulva and lower 1/3 of vagina, perineum, buttocks [1,2,13]
- Vertical (lower) group: penis, scrotum, legs
Picture 8. Lymphogranuloma venereum with bilateral lymph node enlargement in the groin in a man infected with Chlamydia trachomatis (Wikimedia, Creative Commons license)
Causes of enlargement :
- Infections in the leg (cellulitis, lymphangitis, shingles) 
- Fungal infection in the groin: jock itch
- Insect, spider, scorpion or snake bite in the leg (painful node enlargement, redness in the leg) 
- Sexually transmitted diseases (STDs): chancroid, chlamydia, genital herpes, gonorrhea, granuloma inguinale, lymphogranuloma venereum (bilateral node enlargement limited to the groin, urethral or vaginal discharge, burning urination, cloudy urine, genital lesions; Picture 5), HIV/AIDS (groin and also armpit and neck nodes enlarged) 
- Skin cancers on the penis or vulva; rarely other cancers 
- Extrapulmonary tuberculosis (bilateral, nontender) [16,69]
- Tularemia 
- Sarcoidosis 
- Bubonic plague 
- Children: diaper dermatitis in infants
Other causes of lumps in the groin include a hernia, enlarged vein (saphena varix), hidradenitis suppurativa, cysts and lipoma.
13. Supratrochlear Nodes (In the Elbow)
Supratrochlear (epitrochlear, cubital) nodes are located on the inner sides of the elbows (on the pinky finger side). They drain the ulnar aspect (pinky side) of the forearm and hand, pinky, ring and middle finger .
Causes of enlargement [13,16]:
- Local infections in the forearm, hand or fingers
- Tularemia (after a rabbit bite) 
- Lymphoma, melanoma
14. Popliteal Nodes (Behind the Knee)
Popliteal nodes are located behind the knees. They drain the lower legs.
Causes of enlargement: infections or melanoma (skin cancer) in the lower leg, lymphoma
Other causes of lumps behind the knee include ganglion cyst, Baker’s cyst and hemangioma.
The following symptoms and circumstances suggest the possible cause of swollen lymph nodes:
- High fever or a sore throat (flu, infectious mononucleosis, strep throat)
- Low-grade fever (lymphoma, tuberculosis)
- Swollen joints (systemic lupus erythematosus, rheumatoid arthritis)
- A bite–within few days–by a spider, scorpion or snake or–within few months–by a cat (cat-scratch disease), rabbit (tularemia), tick (Lyme disease) or rat flea (bubonic plague)
- Recent use of antibiotics or other medicines
- Unintended weight loss (cancer)
- Armpit pain after drinking alcohol (Hodgkin lymphoma) 
- Recent travel to the South America (typhoid fever, Chagas disease), South Asia (plague) or Africa (sleeping sickness)
- Sexual intercourse with a potentially infected person (STD)
A doctor can detect enlarged lymph nodes by a circular motion of the middle 3 fingers firmly placed over the known lymph node locations (Video 1).
Video 1. Examination of the lymph nodes in the head and neck
Other signs that suggest the cause of swollen lymph nodes:
- Red throat (strep throat, infectious mononucleosis)
- A cut or localized skin infection (cellulitis)
- Rash (ringworm, infectious mononucleosis, SLE, adverse reaction to drugs, shingles, HIV/AIDS)
- The blood culture can reveal the presence of a bacterial infection.
- White blood cells (WBC) are increased in most infections, autoimmune disorders (SLE, rheumatoid arthritis), in lymphoma, other solid cancers and leukemia.
- In infectious mononucleosis, a large percent of “atypical lymphocytes” is present .
- In Hodgkin lymphoma and other solid cancers, WBC can be moderately increased .
- In leukemia, WBC is often higher than 100 x 109/L .
- Tests for sexually transmitted diseases are indicated in sexually active individuals with enlarged lymph nodes in the groin.
Tuberculosis Skin Test
Tuberculosis skin test can reveal the presence of tuberculosis .
- Ultrasound can be used to find and measure the size of the enlarged lymph nodes in the neck, armpits and groin . The Doppler ultrasound can–to some extent–distinguish between benign and malign lymph nodes .
- X-ray can reveal breast or lung cancer and show enlarged lymph nodes in the chest and abdomen .
- CT and MRI can reveal enlarged lymph nodes and cancers in the neck, chest and abdomen.
Biopsy and Histological Examination
When the lymph node swelling persists for more than 3-4 weeks, it means it can result from cancer, a chronic infection, such as tuberculosis, or an autoimmune disorder, such as systemic lupus erythematosus . In this case, a doctor can take a sample of a swollen lymph node in the neck, armpits or groin (by a fine-needle aspiration or FNA) and send it to a pathological laboratory for histological examination under the microscope.
The lymph nodes that are swollen due to acute viral infections, insect bites, autoimmune diseases or adverse reactions to drugs do not require treatment.
Large lymph nodes in chronic infections, such as tuberculosis, can be drained or removed .
The lymph nodes affected by the lymphoma or metastases of other cancers can be removed. For example, in breast cancer, the lymph nodes in the armpit on the same side–into which cancer can spread–are often removed.
Every doctor should know how to check your lymph nodes – there is no specialist that would deal specifically with lymph nodes.
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