Important chest radiography findings associated with pulmonary tuberculosis include miliary nodules (<2 mm) and pulmonary cavitation (Fig. 2) [8, 19, 20]. Air space consolidation is a very nonspecific finding in primary pulmonary tuberculosis, but in combination with hilar or mediastinal lymphadenopathy is associated with pulmonary tuberculosis. Pleural effusions are uncommon in infants and young children with pulmonary tuberculosis, and more common in children >5 years of age. Pleural effusions are usually isolated, though 20% to 40% of children may present with associated parenchymal infiltrate or hilar or mediastinal lymphadenopathy .
US of the mediastinum is an alternative to chest radiograph in identifying lymph nodes and diagnosing pulmonary tuberculosis, especially in a resource-limited setting where sonography may be the only imaging modality. Furthermore, US has no radiation risk to children . Bosch-Marcet et al.  found that 67% of children with pulmonary tuberculosis who had normal chest radiographs had lymphadenopathy on mediastinal US. Moseme et al.  used US to find lymph- adenopathy in 40% of children up to 13 years of age with proven or suspected pulmonary tuberculosis.
Abdominal tuberculosis and HIV coinfection
In contrast to adults, abdominal tuberculosis is uncommon in children with a reported incidence of 10% in those younger than 10 years of age and concomitant pulmonary tuberculosis in 1–5% of cases . The scant paediatric literature on extrapulmonary tuberculosis does not indicate differences in frequency (with the exception of central nervous system tuberculosis) or location in HIV seropositive versus seronegative patients . Therefore, overlap in the imaging findings in both these populations exist. Tuberculosis and HIV coinfection, however, results in more rapid disease evolution and higher mortality. The insidious onset of tuberculosis and its variable clinical features confounds or delays diagnosis with unnecessary laparotomy in some instances or fatality. The clinical presentation may mimic other infectious, inflammatory diseases or malignancy compounding the diagnostic dilemma .
Abdominal tuberculosis is purported to result from haematogenous seeding from primarily pulmonary or other sites or via lymphatic spread from involved lymph nodes or solid viscera . Abdominal tuberculosis may involve single or multiple sites within the bowel, peritoneum, omentum, lymph nodes and solid organs .
US and CT are the main diagnostic modalities . The most common US findings include ascites and mesenteric lymphadenopathy. Portal and peripancreatic lymphadenopathy may be present . CT better demonstrates high density, loculated or free ascites, lymph node conglomerates and central hypoattenuation of nodes. Whilst peripheral rim enhancement of lymph nodes is highly suggestive of tuberculosis infection, this is not pathognomonic . Tuberculosis lymph- adenopathy may be calcified initially or progressively . Para-aortic lymphadenopathy is more likely in lymphoma compared to mesenteric lymphadenopathy in tuberculosis ; however, these conditions may be difficult to distinguish radiologically and coexist in HIV patients.
Inflammatory masses consisting of bowel, omentum and lymphadenopathy (“omental cakes”) can be demonstrated on cross-sectional imaging . A combination of the above features, particularly with rim-enhancing or calcified nodes, is highly suggestive of tuberculosis .
Gastrointestinal tuberculosis commonly involves the terminal ileum and caecum indicated by bowel wall thickening on imaging . This may occasionally be demonstrated on CT, as gastrointestinal contrast studies are not routinely performed in children in this scenario .
Organomegaly and calcified granulomas are frequently the only findings in abdominal tuberculosis. Visceral tuberculosis in the form of splenic microabscesses and hepatic granulomas are frequently part of disseminated (miliary) tuberculosis or as larger abscesses , manifesting as multifocal hypoechogenicities (Fig. 3) or hypodensities (Fig. 4).
Genitourinary tuberculosis is less common with cases of renal cavitation and papillary necrosis described . The kidneys are involved by haematogenous spread.
A high index of suspicion for abdominal tuberculosis in HIV coinfection is warranted in the appropriate clinical setting given the nonspecific clinical presentation and that imaging findings are not pathognomonic.