Imaging of childhood non-Hodgkin lymphoma: assessment by histologic subtype.

The types of childhood non-Hodgkin lymphoma (NHL) differ considerably from Hodgkin lymphoma and NHL seen in adults, both pathologically and clinically. Essential to understanding these differences is a knowledge of the three major histologic subtypes (undifferentiated, lymphoblastic, and large cell) that account for the vast majority of cases of pediatric NHL. Each of these subtypes has typical imaging and clinical features. The most common subtype, undifferentiated NHL, usually shows intraabdominal disease. Lymphoblastic tumors most frequently manifest as a mediastinal mass, perhaps with respiratory or circulatory compromise. Large cell tumors show heterogeneous clinical and imaging features but tend to spare the anterior mediastinum. Knowledge of the appropriate imaging modality to be used in evaluation of these tumors is also important. Computed tomography (CT) is the primary imaging modality for staging childhood NHL. Magnetic resonance imaging is best for examination of the central nervous system and bone involvement. Ultrasonography may be useful as a complementary study to abdominal CT; gallium scintigraphy also plays an adjunctive role to CT. Familiarity with typical and atypical patterns of tumoral behaviors and optimal imaging methods aid in the diagnosis and appropriate follow-up of these tumors.

Ultrasound examination in the diagnosis of popliteal artery aneurysms.

Popliteal artery aneurysm is a potentially limb-threating lesion which is frequently difficult to diagnose by clinical examination or angiography. The risk of limb loss can best be reduced by early diagnosis. Over the past 5 years we have prospectively evaluated ultrasound examination of the popliteal space in screening patients with clinically suspected popliteal artery aneurysms. One hundred patients who were suspected clinically of having a popliteal artery aneurysm underwent bilateral ultrasound examination of their popliteal fossae. There were 21 patients who had abnormal scans. The problems identified were popliteal artery aneurysm in thirteen patients, popliteal artery ectasia in four patients, Baker's cyst in two patients, thrombosis in one patient and popliteal stenosis in one patient. Eight patients with eleven popliteal artery aneurysms by ultrasound also underwent angiography. Seven of the aneurysms were confirmed, four were missed. All eleven aneurysms were confirmed at operation. In addition, angiography did not demonstrate an aneurysm in any patient with a normal ultrasound. This study confirms that ultrasound examination is a quick, accurate, and non-invasive method of screening for popliteal artery aneurysms.