Case4

• Though cervical lymphadenitis can be a manifestation of focal viral infections of the oropharynx or respiratory tract, often it is part of a more generalized reticuloendothelial. response to systemic infection. 
• Viruses commonly associated with prominent cervical adenitis include 
  • Epstein Barr virus (EBV) 
  • cytomegalovirus (CMV) 
  • HIV
• Acute unilateral cervical adenitis is associated in the majority of cases with 
  • Staphylococcus aureus
  • Streptococcus pyogenes
  •  S. aureus causes more frequent fluctuance and longer duration of symptoms. 
• Anaerobic bacteria may cause lymphadenitis usually in association with dental caries and periodontal disease.
• Neonatal cervical adenitis is generally due to S. aureus; however, a cellulitis-adenitis syndrome caused by group B streptococci has been described. Bacteremia occurs in many of these neonatal patients.
• Recurrent cervical adenitis associated with unusual pathogens (Enterobacteriaceae, fungi, Staphylococcus epidermidis) is often associated with a defect in granulocyte function.
• Subacute or chronic cervical adenitis, which develops slowly over two or more weeks is most often caused by cat-scratch disease or mycobacterial infection, and less frequently due toxoplasmosis.
• Bartonella henslae is the presumptive etiologic agent of cat-scratch disease.

2. Describe the pathogenesis of cervical lymphadenitis. 

• The lymphatic system of cervical area serves as a line of defense against infections of the upper respiratory tract, teeth or the soft tissue infections of the face and scalp.
•  Microorganisms that invade these glands are trapped and destroyed by phagocytic cells. 
• The initial histologic response is one of swelling and hyperplasia of sinusoidal lining cells and infiltration of lymphocytes.
•  Suppuration with abscess formation may develop, depending on the organism and age-related host defenses.
•  Conditions that result in significant suppuration of infected nodes include. S. aureus and GABS infections, cat-scratch disease, anaerobic infections and mycobacterial disease.
• Chronic unilateral cervical lymphadenitis is often due to atypical mycobacteria or cat-scratch disease. 
• Cat-scratch disease is sometimes associated with an indolent granulomatous papule, vesicle or ulcer, however, the primary lesion may disappear by the time adenitis is seen..
• The inflammation generally involves a single node or a single group of nodes. 
• Suppuration occurs in over half of the patients.
• Atypical mycobacterial infection is generally localized to a single tonsillar or submandibular node. In mycobacterial infection the nodes are often non-tender, the skin overlaying the node may develop a purple color, the overlying skin may become thinner if untreated. 
• Suppuration develops in about half the cases, followed by skin adhering to the node and spontaneous drainage resulting in fistula formation.
• Biopsied lymph nodes reveal granulomatous inflammation with caseating necrosis in mycobacterial and fungal infections. 
• Granulomatous inflammation by palisading epithelioid cells is seen in cat-scratch disease.

3. What is known about the transmission of the agents? 

• The major portals of entry of the microorganisms that spread to the cervical criands are upper respiratory tract, mouth, teeth and skin.
• Staph aureus, anaerobes and atypical mycobacteria are normal inhabitants of upper respiratory tract.
• Group A Streprococcus, M. tuberculosis and C. diphtheria infection of cervical lymph nodes result from contact with infected humans by way of airborne droplets. Atypical mycobacteria usually enter through the oral mucosa. Organisms ingested in infected meat or through unpasteurized milk may enter the peripharyngeal lymphatics through a break in mucous membranes or secondary to blood stream.
• EBV and CMV are acquired through contact with infected saliva and other body fluids.
• Acute infection following trauma or impetigo or other cutaneous lesions often is due to S. aureus or Group A Streptococci.
• Chronic infection of regional lymph nodes associated with an inoculative skin lesion (lymphocutaneous syndrome) suggest infection due to cat-scratch disease, tuberculosis, nocardia, tularemia, sporotrichosis or cutaneous mycobacterial infection.

4. How is the etiologic diagnosis established? Discuss the role of tuberculin skin test in the diagnosis of mycobacterial adenitis. 

• Establishment of specific cause whenever the infection does not respond to empiric treatment is important. 
• Aspiration of the affected, inflamed node is a valuable diagnostic test. 
• The aspirate should be sent for
  • Gram and acid-fast stains
  • Aerobic, anaerobic, mycobacterial and fungal cultures.

Chronic adenitis

• If the adenopathy is of longer duration (subacute or chronic) and the involved nodes are well localized, non-tender, a granulomatous infection or malignancy is most likely. 
• A history of exposure to TB, insects and animals may help clarify the most likely etiology. 
• If the adenopathy is generalized and particularly if mediastinal nodes are involved, tuberculosis and histoplasmosis are more likely.
• If the adenopathy is unilateral, an atypical mycobacterial infection or cat-scratch disease is more likely.
• The following tests are recommended in such a situation:
  • Intradermal skin testing for tuberculosis (5 IU tuberculin).
  • Serologic testing for EBV, CMV, toxoplasmosis, B. henslae, HIV and fungi.
  • Chest X-ray.

Role of tuberculin skin test in the diagnosis of mycobacterial adenitis. 

• Positive PPD skin test may signify tuberculous infection or cross-reactivity from atypical mycobacterial infection. 
• Abnormal chest x-ray is rare in atypical mycobacterial infection.
• If the diagnosis still remains in doubt and the adenitis is progressing:
• Biopsy of the node should be performed.
• Biopsy material should be submitted for the studies outlined above for lymph node aspirate cultures as well as for routine histology, Giemsa, periodic acid-Schiff (PAS), and methenamine silver stains. 
• Other special stains, for example the Warthin-Starry silver stain for the CSD bacillus, may be requested when appropriate.
• If the histology reveals noncaseating granulomas, and the child has a history of cat exposure, the most likely diagnostic possibility is CSD (cat-scratch disease).

5. Describe the modes of treatment of acute, subacute and chronic bacterial adenitis. 

• Acute suppurative cervical lymphadenitis is most frequently caused by infection with Staphylococcus aureus or group A Streptococcus.
  •  Because of the frequent occurrence of infection due to these two agents, empiric antimicrobial therapy should be directed against them. 
  • The incidence of penicillinase-producing strains of S. aureus is high in most communities, therefore, penicillinase-resistant penicillins should be used.
  •  If the patient requires parenteral therapy, oxacillin or nafcillin may be used, or when oral therapy is deemed to be adequate, cloxacillin or dicloxacillin is recommended. In nodes that progress to rapid suppuration and abscess formation, S. aureus is the most frequent agent isolated and drainage is mandatory. 
• Tuberculosis
  • A 2-month regimen of daily ENH, rifampin, and pyrazinamide followed by a daily regimen of INH and rifampin for 4 months is currently recommended for treatment of uncomplicated intrathoracic pulmonary tuberculosis and isolated cervical lymphadenitis in children.
• Atypical Tuberculosis
  • Cervical lymphadenitis attributed to atypical mycobacteria is much more common in the young child than that caused by M. tuberculosis.
    •  These microorganisms frequently demonstrate in vitro resistance to commonly employed anti-tuberculous drugs.
    •  Surgical excision is the treatment of choice for non-tuberculous mycobacterial lymphadenitis.
• Cat-scratch disease is usually a benign, self-limiting disorder requiring no specific therapy. 
  • Antimicrobials have no effect on the course of this illness. (Few patients have been reported to respond to rifampin therapy.)
  •  If the lymph node progresses to fluctuance, needle aspiration may hasten resolution and also relieve the discomfort caused by the enlarged node.

6. Are there any long-term consequences of cervical adenitis?

Untreated mycobacterial infection may lead to an 

• abscess formation
•  ulceration 
• chronically draining cutaneous fistulae.