Is there a mediastinal shadow in DiGeorge (22q11.2 deletion) syndrome?

From the Guidelines

DiGeorge syndrome (22q11.2 deletion syndrome) typically does not present with a mediastinal shadow on chest radiography. The cardiac and thymic abnormalities associated with this syndrome have different radiographic manifestations. In DiGeorge syndrome, the thymus is usually absent or hypoplastic due to embryological developmental defects affecting the third and fourth pharyngeal pouches. This thymic hypoplasia or aplasia actually results in the absence of the normal thymic shadow rather than the presence of a mediastinal shadow. The cardiac defects commonly seen in DiGeorge syndrome, such as tetralogy of Fallot, interrupted aortic arch, truncus arteriosus, and ventricular septal defects, may cause specific cardiac silhouette abnormalities on chest X-ray but not typically a distinct mediastinal shadow. When evaluating a patient with suspected DiGeorge syndrome, chest imaging should be interpreted in conjunction with other clinical features including facial dysmorphism, hypocalcemia, immunodeficiency, and developmental delays. Definitive diagnosis requires genetic testing to confirm the 22q11.2 deletion, as supported by recent guidelines 1.

Some key points to consider in the diagnosis and management of DiGeorge syndrome include:

• The syndrome is characterized by a wide range of clinical features, including congenital heart defects, immunodeficiency, and developmental delays 1.
• The thymic hypoplasia or aplasia associated with DiGeorge syndrome can result in immunodeficiency, which may manifest as recurrent infections or autoimmune disorders 1.
• Cardiac defects are common in DiGeorge syndrome and may require surgical intervention 1.
• Genetic testing is essential for definitive diagnosis and can help identify individuals with 22q11.2 deletion syndrome 1.
• Management of DiGeorge syndrome requires a multidisciplinary approach, including cardiology, immunology, endocrinology, and genetics, among other specialties 1.

Overall, while DiGeorge syndrome can present with a range of clinical features, a mediastinal shadow on chest radiography is not typically one of them. Instead, the diagnosis is often made based on a combination of clinical features, genetic testing, and imaging studies.

From the Research

Mediastinal Shadow in DiGeorge Syndrome

• The presence of a mediastinal shadow in DiGeorge syndrome is not a typical characteristic of the condition, as the syndrome is often associated with a hypoplastic or aplastic thymus, which would result in a missing thymic shadow on a plain chest x-ray 2.
• However, a case study published in the Korean Journal of Pediatrics in 2015 reported a 7-year-old DiGeorge syndrome patient with a mediastinal mass shadow on her plain chest x-ray, which was later diagnosed as a lymphoproliferative lesion 2.
• This suggests that while a mediastinal shadow is not a common feature of DiGeorge syndrome, it is possible for patients with the condition to develop mediastinal masses or lesions, particularly those with immunodeficiency 2.
• Other studies have focused on the clinical and laboratorial characteristics of DiGeorge syndrome, including conotruncal malformation, facial abnormalities, hypocalcemia, and low lymphocyte count 3, 4, 5, but do not specifically mention the presence of a mediastinal shadow.
• A study on dental aspects in patients with DiGeorge syndrome highlights the importance of considering the medical and dental aspects of the condition, but does not mention mediastinal shadows 6.