Acute cervical lymphadenopathy associated with pharyngitis is characterized by small and rubbery lymph nodes in the anterior cervical chain with minimal to moderate tenderness. Suppurative cervical lymphadenitis, frequently caused by S. aureus or group A streptococcus, shows erythema and warmth of the overlying skin with moderate to exquisite tenderness.
The characteristic triad of EBV infectious mononucleosis is fever, pharyngitis, and lymphadenopathy. The pharynx shows enlarged tonsils and exudate and, sometimes, anenanthem with pharyngeal petechiae. Lymphadenopathy ismost prominent in the anterior and posterior cervical andsubmandibular lymph nodes and less commonly involvesaxillary and inguinal lymph nodes. Other findings includesplenomegaly in 50% of cases, hepatomegaly in 10% to 20%, and maculopapular or urticarial rash in 5% to 15%. A diffuse,erythematous rash develops in approximately 80% of mononucleosis patients treated with amoxicillin. Compared with EBV infection, infectious mononucleosis-like illness caused by CMV has minimal pharyngitis and often more prominentsplenomegaly; it often presents with fever only. The mostcommon manifestation of toxoplasmosis is asymptomaticcervical lymphadenopathy, but approximately 10% of casesof acquired toxoplasmosis develop chronic posterior cervical lymphadenopathy and fatigue, usually without significantfever.
Cat-scratch disease typically presents with a cutaneous papule or conjunctival granuloma at the site of bacterial inoculation, followed by lymphadenopathy of thedraining regional nodes. The nodes are tender, with suppuration in approximately 10% of cases. Lymphadenopathy may persist 1 to 4 months. Less common features ofcat-scratch disease include erythema nodosum, osteolytic lesions, encephalitis, oculoglandular (Parinaud) syndrome,hepatic or splenic granulomas, endocarditis, polyneuritis,and transverse myelitis.
Lymphadenitis caused by nontuberculous mycobacteria usually is unilateral in the cervical, submandibular, or preauricular nodes and is more common in toddlers. The nodes are relatively painless and firm initially, but gradually soften, rupture, and drain over time. The local reaction is circumscribed, and overlying skin may develop a violaceous discoloration without warmth. Fever and systemic symptoms are minimal or absent.
Initial laboratory tests of regional lymphadenopathy include a complete blood count and inflammatory markers. Infectious mononucleosis is characterized by lymphocytosis with atypical lymphocytes; thrombocytopenia and elevated hepatic enzymes are common.
Cultures of infected skin lesions and tonsillar exudates should be obtained. Isolation of group A streptococci from the oropharynx suggests, but does not confirm, streptococcal cervical lymphadenitis. A blood culture should be obtained from children with systemic signs and symptoms of bacteremia.
Serologic testing for EBV and for B. henselae should be obtained if there are appropriate findings. The most reliable test for diagnosis of acute EBV infection is the IgM antiviral capsid antigen (Fig. 99-1). Heterophil antibody is also diagnostic but is not reliably positive in children younger than 4 years with infectious mononucleosis.