Mycobacterial Cervical Lymphadenitis in Children: Clinical and Laboratory Factors of Importance for Differential Diagnosis
Cervical lymphadenitis is the most common manifestation of extrapulmonary tuberculosis in children. A noteworthy decrease in the number of children with MTB lymphadenitis has been observed in the authors' clinic during the 1990s.

NTM cervical lymphadenitis has been recognized with increasing frequency in young immunocompetent children during the 1990s. This may be partially related to the increased awareness of paediatricians to these infections; however, the increasing virulence of these organisms may play a role.

In a young childe with unilateral, submandibular or anterior cervical lymphadenitis in the abscence of signs or symptoms of common bacterial infection, mycobacteria should be highly considered as a likely diagnosis. In the present series several demographic, socioeconomic and clinical parameters were analysed. Prompt distinction between MTB complex and NTM cervical lymphadenitis is critical not only for the investigation of cases required in the former, but mainly because of the different therapeutic interventions. In particular, a prolonged antituberculous regimen is the cornerstone of treatment for MTB complex lymphadenitis, as opposed to the wide surgical excision required for NTM lymphadenitis. Although diagnosis is always confirmed microbiologically, mycobacterial growth may take up to 8 weeks.

Recently the American Academy of Pediatrics adopted a TST reaction >=5mm in an unvaccinated child with a pathologic chest radiograph or a positive contact history as suggestive of tuberculosis.
In our study meeting 2 out of 3 criteria:
(α) a TST reaction of >=10mm
(β) positive chest radiograph
(γ) exposure to MTB
resulted in 92% sensitivity.

Criteria for the differential diagnosis of mycobacterial lymphadenitis (in the absence of positive cultures)
CriteriaPatients with MTB lymphadenitis
Patients with NTM lymphadenitis
Exposure to MTB15 (62,5%)0 (0%)<0,001
Pulmonary tuberculosis on CXR15 (62,5%)0 (0%)<0,001
Median TST reaction, mm (range)16 (11-22 mm)7 (0-11 mm)<0,001

However, a presumptive diagnosis should never disregard the value of microbiological confirmation. Vigorous efforts to isolate the responsible mycobacterium through gastric fluid or lymph node cultures are highly justified and recommended.

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