Axillary (arm pit) lymph node enlargement
Normally axillary lymph nodes are not felt. However, sometimes in normal people, they are felt as small (less than 1cm in diameter), soft, non-tender swellings. Large tender but mobile lymph nodes usually indicate infections or small wounds of the arm (as a skin infection or a cat scratch). Harder, fixed or matted axillary nodes often indicate malignancy usually from the lung or breast.
Causes of axillary (arm pit) lymph node enlargement
In localized axillary lymphadenopathy (disease of the lymph nodes), the enlargement is restricted to lymph nodes in the axillary areas (both arm pits). If lymph nodes in other areas (e.g., the neck) are also enlarged in addition to those in the arm pits, then the condition should be evaluated as a case of generalized lymphadenopathy.
That said, the evaluation of axillary lymphadenopathy should take into consideration systemic causes of lymph node enlargement as this could be an early manifestation of a more generalized lymphadenopathy.
Axillary lymph node enlargement
- Location: Located in the axillae (arm pits).
- Lymphatic drainage: Arm, thoracic wall, breast.
- Common causes: Infections, cat-scratch disease, lymphoma, breast cancer, silicone implants, brucellosis, melanoma.
Some of the causes of axillary lymphadenopathy
- localized infection, possibly somewhere in the arm or breast draining into the glands of the armpit, or infection within the armpit itself
- cat scratch disease
- ascending lymphangitis
- lymphadenitis, lymphangitis
- infectious mononucleosis
- herpes zoster (shingles)
- HIV disease (AIDS)
- Hodgkin's lymphoma
- non-Hodgkin's lymphoma
- Breast cancer
- Lung cancer
- smallpox vaccination
- typhoid vaccine
- measles, mumps, rubella vaccine (rare)
- allergic reaction possibly caused by sulfa drugs, iodine, or penicillin
Epidemiology and statistics
Only one study provides reliable population-based estimates. Findings from this Dutch study revealed a 0.6 percent annual incidence of unexplained lymphadenopathy in the general population.
Clinical features of abnormal lymph node enlargement
Abnormal lymph node enlargement tends to commonly result from infection / immune response, cancer and less commonly due to infiltration of macrophages filled with metabolite deposits (e.g., storage disorders).
Infected Lymph nodes tend to be firm, tender, enlarged and warm. Inflammation can spread to the overlying skin, causing it to appear reddened.
Lymph nodes harboring malignant disease tend to be firm, non-tender, matted (i.e., stuck to each other), fixed (i.e., not freely mobile but rather stuck down to underlying tissue), and increase in size over time.
Sometimes, following infection lymph nodes occasionally remain permanently enlarged, though they should be non-tender, small (less the 1 cm), have a rubbery consistency and none of the characteristics described for malignancy or for infection. These are also known as 'Shotty Lymph nodes'.
Size and clinical significance
Nodes are generally considered to be normal if they are up to 1 cm in diameter; however, some authors suggest that epitrochlear nodes larger than 0.5 cm or inguinal nodes larger than 1.5 cm should be considered abnormal [2,3].
Little information exists to suggest that a specific diagnosis can be based on node size. However, in one series  of 213 adults with unexplained lymphadenopathy, no patient with a lymph node smaller than 1 cm2 had cancer, while cancer was present in 8 percent of those with nodes from 1 cm2 to 2.25 cm2 in size, and in 38 percent of those with nodes larger than 2.25 cm2. These studies were performed in referral centers, and conclusions may not apply in primary care settings.
In children, lymph nodes larger than 2 cm in diameter (along with an abnormal chest radiograph and the absence of ear, nose and throat symptoms) were predictive of granulomatous diseases (ie, tuberculosis, cat-scratch disease or sarcoidosis) or cancer (predominantly lymphomas) .
An increase in nodal size on serial examinations is significant. Hence nodes that continue to grow in size are important and those that regress in size tend to be more reassuring.
Pain/Tenderness. When a lymph node rapidly increases in size, its capsule stretches and causes pain. Pain is usually the result of an inflammatory process or suppuration, but pain may also result from hemorrhage into the necrotic center of a malignant node. The presence or absence of tenderness does not reliably differentiate benign from malignant nodes.
ConsistencyStony-hard nodes are typically a sign of cancer, usually metastatic. Very firm, rubbery nodes suggest lymphoma. Softer nodes are the result of infections or inflammatory conditions. Suppurant nodes may be fluctuant. The term "shotty" refers to small nodes that feel like buckshot under the skin, as found in the cervical nodes of children with viral illnesses.
MattingA group of nodes that feels connected and seems to move as a unit is said to be "matted." Nodes that are matted can be either benign (e.g., tuberculosis, sarcoidosis or lymphogranuloma venereum) or malignant (e.g., metastatic carcinoma or lymphomas).
Constitutional symptomsConstitutional symptoms such as fever, weight loss, fatigue or night sweats could suggest disorders such as tuberculosis, lymphoma, collagen vascular diseases, unrecognized infection or malignancy. The presence of fever is commonly associated with infections.
This method has a low sensitivity and specificity 60-70%; however, is the first step in the evaluation of lymph node enlargement.
Ultrasound is a useful imaging modality in assessment of lymph nodes. Distribution of nodes, grey scale and power Doppler sonographic features are useful to identify the cause of cervical lymphadenopathy. Useful grey scale features include size, shape, status of echogenic hilus, echogenicity, micronodular appearance, intranodal necrosis and calcification. Adjacent soft tissue edema and matting are particularly useful to identify tuberculosis. Useful power Doppler features include vascular pattern and displacement of vascularity.Ultrasonography can be combined with fine needle aspiration cytology in which a sample of cells from the lymph node is aspirated using a needle and examined under the microscope.
CT scans can detect the presence of enlarged axillary lymph nodes with a short-axis diameter of 5 mm or greater.
Is it cancer?
Findings from a Dutch study revealed that only 10 percent of patients with unexplained adenopathy required referral to a subspecialist, 3 percent required a biopsy and only 1 percent had a malignancy.
In primary care settings, patients 40 years of age and older with unexplained lymphadenopathy have about a 4 percent risk of cancer versus a 0.4 percent risk in patients younger than age 40.
How to proceed
If the lymph node enlargement is unexplained, it may need to undergo a period of observation for 3 to 4 weeks possibly with the addition of empirical antibiotics.
If it persists after a period of observation then the patient should seek medical attention which may require further investigations using ultrasonography and fine needle aspiration cytology or an excisional biopsy.
1. Fijten GH, Blijham GH. Unexplained lymphadenopathy in family practice. An evaluation of the probability of malignant causes and the effectiveness of physicians' workup. J Fam Pract 1988;27: 373-6.2. Libman H. Generalized lymphadenopathy. J Gen Intern Med 1987;2:48-58.
3. Morland B. Lymphadenopathy. Arch Dis Child 1995; 73:476-9.4. Pangalis GA, Vassilakopoulos TP, Boussiotis VA, Fessas P. Clinical approach to lymphadenopathy. Semin Oncol 1993;20:570-82.
5. Slap GB, Brooks JS, Schwartz JS. When to perform biopsies of enlarged peripheral lymph nodes in young patients. JAMA 1984;252:1321-6.
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