Scrofula is a disease characterized by cervicofacial lymphadenitis as a result of mycobacterial infection. Interestingly, the species of mycobacteria tend to vary based on the age of the infected person. In adults, scrofula is the result of primary infection by Mycobacteria tuberculosis. However, in children, the most common cause of scrofula is infection by nontuberculous mycobacteria (NTM), of which the most frequent agents are M. avium and M. haemophilum.1–3 This difference in etiological agents shows both clear similarities and marked differences in the disease processes, diagnoses, treatments, and prognoses for both age groups.
In adults, scrofula is most commonly due to infection by M. tuberculosis, which is spread via respiratory transmission from person-to-person. In the case of scrofula, M. tuberculosis spreads from the initial site of infection, typically the lungs, through the lymphatic system to the cervicofacial lymph nodes.1 The immunocompromised, especially those with HIV, are at a 500 times higher risk for tuberculosis and at higher risk of extrapulmonary spread.1,3
In contrast, NTM are not transmittable from person-to-person and abundant in the environment, especially in soil.4,5 Children, especially those ages 1-5, may be at higher risk for infection by NTM than adults due to their predilection for placing contaminated objects in their mouths.1,4,5 Furthermore, entry into the body is facilitated by the eruption of the primary teeth and by soft tissue lesions of the oral cavity, which is common in children.5 Unlike in adults, pediatric scrofula typically affects the immunocompetent.1
Scrofula presents similarly in both age groups. Early stages of scrofula present with slowly enlarging, non-tender, firm lymph nodes with a median size of 3 centimeters.1,3,4 Most cases are unilateral and involve multiple lymph nodes.1,3 The most commonly affected nodes are the submandibular, parotid, pre-auricular, submental, supraclavicular, and jugulodigastric.1,4,5 Infected lymph nodes will develop caseating granulomas resulting in liquefaction of the lymph nodes. If left untreated, fistulas may form, connecting the lymph nodes to the skin.1,4 In cases caused by NTM, characteristic skin changes overlying the affected lymph nodes occur such as violaceous color change and skin thinning.4 Exclusive to tuberculosis, patients experience systemic symptoms such as fever, chills, weight loss, or malaise.1,3
In both adults and children, differential diagnoses must be considered in order to definitively diagnose scrofula. Other causes of cervical lymphadenopathy, such as Bartonella hensellae, Epstein Barr virus, cytomegalovirus, staphylococcus, streptococcus, and non-infectious conditions such as malignancies should be considered.1,3 The gold standard of diagnosis via culture or PCR of sample obtained via fine-needle aspiration of an affected lymph node.1,3 However, PCR equipment is not readily available in many settings and culturing NTM is difficult with a turn-around time between 2-8 weeks, which may limit the immediate utility of these techniques in many clinical settings.1–3 Purified protein derivative (PPD) skin testing can be used to screen for tuberculosis, although patients with NTM may show a partial response.1 In children, it may be possible to utilize PPD testing to differentiate tuberculosis from NTM utilizing induration size.2 History, especially for potential exposure to tuberculosis, is important for diagnosis as well.1
Treatment of adult scrofula caused by M. tuberculosis follows the standard drug-based therapy of rifampin, pyrazinamide, isoniazid, and ethambutol for 2 months followed by isoniazid and rifampin for 4 months.1,3 Prognosis is good with cure rates between 89%-94% with disseminated disease being the most dangerous complication.1,3 For children with scrofula due to NTM, surgical excision of the affected nodes has been demonstrated to be superior to drug-based therapies, most commonly clarithromycin or rifabutin, or curettage.1,5,6 Surgery has a very high rate of success and low chance of recurrence, however, scarring is not uncommon and facial nerve dysfunction, although rare, may result.1,6