Teaching Case

An 8-year-old boy was admitted to ED with fever, temporal headache and left cervical lymphadenopathy for two weeks. Physical examination and blood work-up were normal except for a left tonsillar phlegmon, which was incised before imaging. Given persistent symptoms, the patient was hospitalised for further investigations.

A chest X-ray was negative. Neck ultrasound demonstrated numerous enlarged lymph nodes, especially on the left, the largest measuring 4.3 x 1.3 cm (Fig. 1). Abdominal ultrasound showed numerous hypoechoic lesions in the hepatic and renal parenchyma, with peripheral vascularisation with Doppler interrogation (Fig. 2). No lymphadenopathy or splenomegaly was found.

At abdominal MR the hepatic lesions appeared mildly T2 hyperintense, T1 hypointense (Fig. 3), with high signal on diffusion-weighted imaging (DWI) (Fig. 4), and apparent peripheral enhancement with a central hypovascular component (Fig. 5). Neck MR showed a large solid mass arising from the left pharyngeal tonsil and extending to the rhinopharynx, nasal fossa and pterygo-palatine fossa, and reaching the prevertebral space (Fig. 6), highly suspicious of a malignant process.

Pharyngeal biopsy led to the final diagnosis of Burkitt lymphoma (BL), negative for t (8;14) translocation.

BL is an aggressive subtype of non-Hodgkin lymphoma with a doubling time of 24-48 hours [1]. In 90-95% of cases it is caused by translocation t(8;14), involving c-myc gene and immunoglobulin heavy-chain locus [2]. Male-to-female ratios range from 1.3:1 to 8.8:1; the median age of affected children is 8 years [3].
The WHO classification of BL describes three clinical variants: endemic, sporadic (the predominant type in non-malarial areas) and immunodeficiency-related [4].
The abdominal and pelvic region is commonly affected by BL, particularly by its sporadic form. The ileocaecal region, specifically Peyer’s patches, is the most common site involved along the gastrointestinal tract, because the terminal ileum has the highest concentration of lymphatic tissue [1].
EBV is found in almost all cases of endemic BL, while it is rarely associated with the sporadic type [4]. In our case EBV IgG search was negative.
Although primary involvement of solid organs is rare, secondary involvement of the liver, spleen, or kidney is not uncommon. Radiologic findings include organomegaly and single or multiple focal hypoechoic masses on ultrasound [1].
Even with its aggressive character, BL is curable and highly sensitive to chemotherapy. Thus, knowledge of proper imaging features is fundamental for early diagnosis and treatment [1].
Sonography plays an important role in differential diagnosis of lymph node swelling in children, caused in most patients by a diagnosable infectious disease [5, 6]. In our case the findings at neck ultrasound led us to consider possible infectious aetiology, considering the global clinical history (fever, phlegmon, cephalea) even if lymphomatous disease could not be excluded. Nonetheless the presence of concurrent multiple hypoechoic lesions in the hepatic and renal parenchyma suggested differential diagnoses such as multiple abscesses, parenchymal localisation of lymphoma and metastases of unknown origin.
Neck and pharyngeal infiltration and enlarged nodes are seen in 25% of children with BL; the primary mass usually appears isointense on T1-weighted MR images, hyperintense on T2-weighted images [7], with high signal on DWI and heterogeneous enhancement after contrast material administration.
Hepatic involvement in BL has been reported in approximately 17% of patients, presenting as hypoechoic lesions on ultrasound. Renal involvement of BL most commonly includes nephromegaly (90%), focal renal masses (30%) and hydronephrosis due to ureteral obstruction (50%). At ultrasound, the kidneys may show increased cortical echogenicity (60%) with or without iso or hypoechoic masses [3].
Our patient, after 6 months of chemotherapy, completely healed from BL and currently undergoes periodic follow-up examinations.