Clear cell sarcoma of the pediatric kidney: detailed description and analysis of variant histologic patterns of a tumor with many faces.

Clear cell sarcoma of the kidney is the most frequently misdiagnosed renal tumor in children. The majority of tumors present the classic histologic pattern, which allows a definitive diagnosis. However, there are unusual cases with lack of "clear" appearance of tumor cells, predominance or exclusive presence of variant histologic patterns, and presence of "neoplastic" appearing entrapped tubules. Furthermore, a small biopsy specimen may not show the classic histologic pattern. These tumors present a diagnostic challenge for the practicing pathologist who should be aware of the deviations from the classic histologic features in order to make a correct diagnosis.

Splenic arteries and veins in pediatric sickle cell disease.

The goal of this study was to verify the existence and prevalence of large vessel lesions outside the central nervous system in young patients with sickle cell disease. Thus, 17 spleens resected because of episodes of sequestration or infarction and 41 controls were studied. Anomalies of arteries and veins were detected in all spleens from sickle cell disease patients, but no definite correlation with age, sex, type of sickle hemoglobin, or frequency of sequestration episodes could be established. The most consistent lesions were intimal proliferation affecting large arteries and veins, reduplication of the internal elastic lamina of large arteries, and a lesion not previously documented in this condition, that of subendothelial infiltration of the large veins by activated T cells. Endotheliitis showing some similarity with the one seen in sickle cell disease spleens was noted in 5 of 41 spleens of patients who did not suffer from sickle cell disease. However, when present it was usually mild. Very limited damage to the arterial elastica was noted in only 1 of the 41 controls. Minimal endothelial proliferation was seen in 2 of 41 controls.