Follow-up studies of multicystic dysplastic kidneys.

Thirty cases of multicystic dysplastic kidney (MCDK) were diagnosed over 11 years. Nine patients underwent nephrectomy: three for increasing kidney size (classic MCDK) and six because of an inconclusive diagnosis (hydronephrotic MCDK). Of the remaining 21 patients, 19 were followed up for a mean of 33.5 months (range, 2-101 months). Follow-up ultrasound examinations revealed that 16 kidneys did not change in size, one decreased in size after cyst puncture, and two disappeared (one after cyst puncture). This series included one case of non-renin-producing hypertension that was controlled medically, one case of nephroblastomatosis found in the removed dysplastic kidney, and one case of pyelonephritis in the contralateral kidney. When the diagnosis of classic MCDK is made with imaging modalities, the lesion may not have to be removed unless there is growth of the mass during the 1st year of life. Nine percent of these lesions will disappear within the first 3 years of follow-up, and the authors recommend an even longer period of follow-up.

Immune thrombocytopenic purpura. Use of a 125I-labeled antihuman IgG monoclonal antibody to quantify platelet-bound IgG.

We used a radiolabeled monoclonal antibody to the Fc portion of human IgG to measure platelet-bound IgG in 54 thrombocytopenic patients and in 48 normal controls. The control group had a mean (+/- 1 S.D.) of 169 +/- 79 IgG molecules bound per platelet--10 to 100 times lower than values generally reported with other assay techniques. Sixteen of 17 patients with untreated thrombocytopenic purpura considered to be of immune origin had values ranging from 790 to 13,095--levels well above those found in normal subjects and in patients with "nonimmune" thrombocytopenia (246 +/- 156). In a second group, consisting of 11 patients with "immune" thrombocytopenic purpura who did not respond to conventional therapy (corticosteroids or splenectomy), the values were quite divergent: two patients had levels in the normal range, three had levels in the range of subjects with nonimmune thrombocytopenia, and six had much higher levels. Measurement of platelet-bound IgG with this monoclonal-antibody technique can help differentiate between immune and nonimmune thrombocytopenias. Low platelet counts in patients who have immune thrombocytopenia according to clinical criteria but are resistant to therapy may be related to factors other than IgG antibody.