(See also Overview of Bacterial Skin Infections Overview of Bacterial Skin Infections Bacterial skin infections can be classified as skin and soft-tissue infections (SSTI) and acute bacterial skin and skin structure infections (ABSSSI). SSTI include Carbuncles Ecthyma Erythrasma read more and Lymphangitis Lymphangitis Lymphangitis is acute bacterial infection (usually streptococcal) of peripheral lymphatic channels. Symptoms include erythematous, irregular, warm, tender streaks that develop on an extremity... read more 
.)
Lymphadenitis is a feature of many bacterial, viral, fungal, and protozoal infections.
Focal lymphadenitis is prominent in the following:
Tuberculosis Tuberculosis (TB) Tuberculosis is a chronic, progressive mycobacterial infection, often with an asymptomatic latent period following initial infection. Tuberculosis most commonly affects the lungs. Symptoms include... read more
or nontuberculous mycobacterial infection Nontuberculous Mycobacterial Infections There are over 170 recognized species of mycobacteria, mostly environmental. Environmental exposure to many of these organisms is common, but most exposures do not cause infection and many infections... read more
Multifocal lymphadenitis may occur in patients with the following:
Symptoms and Signs of Lymphadenitis
Lymphadenitis typically causes pain, tenderness, and lymph node enlargement. Pain and tenderness typically distinguish lymphadenitis from lymphadenopathy. With some infections, the overlying skin is inflamed, occasionally with cellulitis Cellulitis Cellulitis is acute bacterial infection of the skin and subcutaneous tissue most often caused by streptococci or staphylococci. Symptoms and signs are pain, warmth, rapidly spreading erythema... read more 
. Abscesses may form, and penetration to the skin produces draining sinuses. Fever is common.
Diagnosis of Lymphadenitis
Clinical evaluation
Sometimes aspiration and culture or excisional biopsy
The underlying disorder is usually suggested by history and examination. Enlarged lymph nodes that do not cause pain, tenderness, or erythema may raise concern for other disorders such as lymphomas Overview of Lymphoma Lymphomas are a heterogeneous group of tumors arising in the reticuloendothelial and lymphatic systems. The major types are Hodgkin lymphoma Non-Hodgkin lymphoma See table Comparison of Hodgkin... read more .
If not, aspiration and culture or excisional biopsy is indicated (1 Diagnosis reference Lymphadenitis is an acute infection of one or more lymph nodes. Symptoms include pain, tenderness, and lymph node enlargement. Diagnosis is typically clinical. Treatment is usually empiric.... read more 
).
Diagnosis reference
1. Olivas-Mazón R, Blázquez-Gamero D, Alberti-Masgrau N, et al: Diagnosis of nontuberculous mycobacterial lymphadenitis: The role of fine-needle aspiration. Eur J Pediatr 180(4):1279–1286, 2021. doi: 10.1007/s00431-020-03875-2
Treatment of Lymphadenitis
Treatment of cause
Treatment of lymphadenitis is directed at the cause and is usually empiric.
Empiric options include IV antibiotics, typically directed at Staphylococcus aureus and Streptococcus pyogenes or atypical mycobacterial infections; antifungals; and antiparasitics depending on etiology or clinical suspicion. Many patients with lymphadenitis may respond to outpatient therapy with oral antibiotics. However, many patients also go on to form abscesses Cutaneous Abscess A cutaneous abscess is a localized collection of pus in the skin and may occur on any skin surface. Symptoms and signs are pain and a tender and firm or fluctuant swelling. Diagnosis is usually... read more , which require surgical drainage; an extensive procedure is done with accompanying IV antibiotics. In children, IV antibiotics are commonly needed.
Hot, wet compresses may relieve some pain.
Lymphadenitis usually resolves with timely treatment, although residual, persistent, nontender lymphadenopathy is common.
