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Biomedical subjects

H S Chan

Publications and source records attributed to H S Chan.

At least 145 records · Page 8Linked to original sources
PubMed1984

Synovial sarcoma in childhood.

The clinical and radiologic findings in seven children with synovial sarcoma are described. The five boys and two girls had a mean age at presentation of 4.4 years. All seven had the lesion situated in an extremity. Plain radiographs in four revealed the presence of a soft-tissue mass with no calcification or bone and joint involvement. In two patients studied with computed tomography (CT), the primary lesions had peripheral irregular areas of enhancement with central areas of poor enhancement, reflecting the necrotic, cystic, and hemorrhagic changes found in the centers of these tumors. Although the exact margins of these lesions were difficult to define accurately even with intravenous contrast enhancement, CT is still recommended as the best imaging method for assessing the local extent of the primary tumor and is a useful tool in the planning of appropriate therapy as well as the gauging of tumor response to ongoing treatment.

Age Factors↗
PubMed1984

Occult neuroblastoma presenting with opsomyoclonus: utility of computed tomography.

The clinical and radiographic findings in 10 children with neuroblastoma presenting with opsomyoclonus are described and the literature is reviewed. Children with opsomyoclonus are often a diagnostic dilemma, as they may not have a palpable tumor or increased urinary catecholamines. Computed tomography (CT) is the most sensitive imaging method in locating tumors (100%) compared with plain radiography of the chest and abdomen (sensitivity 40%), excretory urography (50%), and 99mTc radionuclide bone scans (50%). The use of body CT significantly shortened the interval between initial presentation and final diagnosis and avoided multiple hospitalizations and unnecessary investigations for patients with persistent opsomyoclonus. Since most neuroblastomas are solitary lesions that may arise in the adrenal glands or along the sympathetic chain from the neck down into the pelvis, our policy is to use plain radiography, sonography, and 99mTc methylene diphosphonate (MDP) bone scans for the preliminary investigation of patients with opsomyoclonus. Body CT can then be tailored to suit the needs of the individual patients.

Abdominal Neoplasms↗
PubMed1983

Extragonadal endodermal sinus tumors in children: a review of 24 cases.

Endodermal sinus tumors (EST) are highly malignant lesions with a tendency to recur locally and with a high incidence of metastatic disease at the time of diagnosis. The clinical and radiographic spectra of 24 patients with extragonadal EST are reported. There were 17 females and seven males and the mean age of presentation was 21 months. The primary lesion occurred in the sacrococcygeal region in 16 patients; in the vagina in two patients; in the anterior mediastinum in two patients; and in the bladder, liver, nasopharynx and posterior cranial fossa in one patient each. Computed tomography (CT) is the most accurate study in delineating the extent of primary lesions particularly in the pelvis and head and neck and also for demonstrating metastatic disease in the lungs. Significant improvement in survival rates is obtained with a combination of surgery, chemotherapy and radiotherapy.

Child, Preschool↗
PubMed1983

Adrenal carcinoma and adenoma in children: a review of 17 patients.

Seventeen children with adrenocortical neoplasms (13 carcinomas: four adenomas) are reviewed and attention is focused on the value of the newer imaging modalities in the management of these children. All the lesions were functioning tumors. CT is the single most important modality in assessing primary and metastatic disease at diagnosis and during follow-up. In children suspected of having an adrenal lesion, high resolution CT will promptly localize the lesion to an adrenal. Since the only curative treatment is complete surgical removal CT plays an important role in defining the extent of the primary lesion pre-operatively. Large carcinomas have an inhomogeneous density on CT and a complex echo pattern on ultrasound reflecting the areas of hemorrhage and necrosis seen macroscopically in these lesions. Smaller lesions have a more homogeneous density on CT but benign and malignant disease could not be differentiated by this modality. Ultrasound is useful in screening the adrenal area in those patients in whom there is a low clinical index of suspicion for an adrenal tumor and also in the post-operative period.

Adenoma↗
PubMed1983

Renal cell carcinoma in the first two decades of life.

Renal cell carcinoma occurs rarely in the first two decades of life. This paper reviews the clinical and radiographic features of 17 such patients (10F: 7M, mean age = 12 years) seen in a 24 year period. The almost equal sex incidence contrasts with the male preponderance in adults. All patients presented with symptoms and signs referable to the primary lesion. In comparison to Wilms' tumor, renal cell carcinoma in childhood and adolescence usually presents with a smaller abdominal mass which is frequently not palpable or visible on plain abdominal radiographs. Ultrasound and CT showed non-specific solid intrarenal masses. This rare tumor of childhood should be included in the differential diagnosis of intrarenal mass lesions, particularly in older children with hematuria and renal calcification on plain radiographs. One child in this series had tuberous sclerosis. The prognosis depends on the stage of disease at presentation.

Adenocarcinoma↗
PubMed1983

Cardiac metastases from osteosarcoma. A report of two cases.

Two children who developed cardiac metastases from osteogenic sarcoma are described, and the value of computed tomography in making an antemortem diagnosis is illustrated. Computed tomographic images with a narrow window width will reveal the presence of calcification within the cardiac metastases. Images in this mode should always be studied in patients with osteogenic sarcoma who are undergoing chest computed tomography scans to detect pulmonary metastases.

Adolescent↗
PubMed1983

Aggressive fibromatosis in childhood. Computed tomographic findings in three patients.

Three children with aggressive fibromatosis are presented and the value of computed tomography in defining the extent of the lesions and for follow-up and treatment planning is discussed. Aggressive fibromatosis is a nonmetastasizing fibrous lesion with a propensity for local invasion and recurrence after surgery. The lesions usually have a poorly defined margin on computed tomography and the attenuation coefficient is less than that of muscle with poor enhancement following intravenous administration of contrast material.

Adolescent↗
PubMed1983

Computed tomography and lymphogram correlation in children with Hodgkin's disease.

In 17 children with Hodgkin's disease, abdominal computed tomography (CT) and bipedal lymphangiography findings were correlated in an attempt to assess the accuracy of CT in excluding the presence of retroperitoneal and pelvic lymphadenopathy. There was excellent correlation in 14 (82%) patients. In 13 of these, both studies were negative; in one, enlarged nodes were noted in the pelvis on both studies, which otherwise revealed no abnormality in the remainder of the abdomen. In one other patient, CT revealed lymphadenopathy high in the abdomen and these nodes were not filled with contrast medium at lymphangiography. Lymphangiography revealed pelvic lymphadenopathy in 2 (12%) patients in whom the CT scan was initially interpreted as normal. If strict attention is paid to adequate opacification of the bowel and retroperitoneal vasculature, CT is an accurate modality for excluding retroperitoneal and pelvic lymphadenopathy, particularly in older children.

Adolescent↗
PubMed1982

Diamond-Blackfan syndrome. I. Erythropoiesis in prednisone responsive and resistant disease.

We studied the in vitro proliferative characteristics of marrow erythroid progenitors, colony forming unit-erythroid (CFU-E) and burst forming unit-erythroid (BFU-E), in two infants with Diamond-Blackfan syndrome before and during prednisone treatment. Patient 1, had a brisk erythropoietic response to prednisone and the anemia improved; Patient 2 was steroid-unresponsive. Marrow from Patient 1 yielded linear increases in numbers of colonies in erythropoietin dose-response studies, and the magnitude of response was much greater while on prednisone compared to pretreatment. Cultures of stem cell rich fractions of marrow from Patient 1 separated by unit gravity sedimentation (STA-PUT) revealed moderately reduced CFU-E and BFU-E numbers before prednisone, but normal colony numbers during treatment. Patient 2 differed because CFU-E and BFU-E were almost absent at all erythropoietin doses before and during therapy. Even stem cell rich marrow fraction initially yielded very low colony numbers which did not increase significantly while on prednisone. These findings suggest that in Patient 1 there were adequate numbers of progenitors that were able to differentiate normally only in the presence of prednisone. In Patient 2 the erythropoietic failure in vivo and in vitro was unaffected by prednisone.

Anemia, Aplastic↗
PubMed1982

Diamond-Blackfan syndrome. II. In vitro corticosteroid effect on erythropoiesis.

To study the action of corticosteroids on erythroid precursors, (burst forming unit-erythroid and colony forming unit-erythroid) in Diamond-Blackfan Syndrome (DBS), marrow from a newly diagnosed untreated infant was studied in vitro with prednisone and dexamethasone. This patient subsequently proved to be steroid responsive. Colony numbers increased linearly in an erythropoietin (EPO) dose response study. There was marked enhancement of colony numbers at all EPO doses after adding either prednisone (10(-6) M) or dexamethasone (10(-9) M) to the cultures. The data indicate that corticosteroids augment erythropoiesis at both early (BFU-E) and late (CFU-E) stages of development in DBS. In contrast, marrow from a second infant with DBS, clinically steroid resistant, failed to respond to steroids in vitro.

Anemia, Aplastic↗
PubMed1981

Lithium therapy of children with chronic neutropenia.

We treated five children with chronic neutropenia using lithium carbonate and studied the effect in vivo on granulopoiesis. Granulocyte precursors (CFU-C) from blood and marrow, and colony-stimulating activity (CSA) from peripheral blood leukocytes, were assayed in a methylcellulose tissue culture system. Three patterns of response to lithium were seen. In patients with aplastic anemia (one acquired and two Fanconi's aplastic anemia) despite increased colony-stimulating activity, CFU-C numbers remained very low and the neutropenia persisted. In a patient with Kostmann neutropenia colony-stimulating activity, and blood and marrow CFU-C numbers increased, but the agranulocytosis was unchanged. An impressive therapeutic effect was seen in one patient with idiopathic neutropenia with low colony-stimulating activity who responded to lithium with an increase in colony-stimulating activity and CFU-C resulting in persisting normal neutrophil counts. Lithium appears useful in treating a select group of neutropenic patients in whom colony-stimulating activity production is responsive to lithium, and the granulocytic progenitor compartment is capable of producing mature neutrophils.

Adolescent↗
PubMed1981

Placental involvement in congenital neuroblastoma.

We describe two cases of congenital neuroblastoma involving the placenta and review previously reported cases. The placentae in congenital neuroblastoma have a bulky, hydropic appearance, and contain tumour cells which are confined to the fetal circulation. The tumour emboli are not macroscopically identifiable. Pathophysiological mechanisms of placental involvement by fetal and maternal malignancies are considered. The rarity of this lesion may be artefactual, and may result from failure to examine grossly enlarged placentae in cases of stillbirth and hydrops fetalis. Congenital malignancy must be considered in the differential diagnosis of an abnormally large placenta.

Adrenal Gland Neoplasms↗
PubMed1978

Phthalate ester plasticizers: a new class of marine pollutant.

Phthalate ester plasticizers have been detected in the open-ocean environment. Samples consisting of water, sediment, air, and biota from the Gulf of Mexico and of water and air from the North Atlantic were analyzed and found to contain two phthalate esters, di-(2-ethylhexyl) phthalate (DEHP) and di-n-dibutyl phthalate (DBP): the concentrations of polychlorinated biphenyls (PCB's) and DDT's (p,p'-DDT and p,p'-DDE) were also determined. Like the ubiquitous PCB's and DDT's, the phthalate plasticizers were found in almost all samples analyzed; DEHP was present at higher concentrations than the PCB's or DDT's in water and sediment. The environmental impact of the concentrations found in these studies, coupled with the continued high production and wise use of these plasticizers, requires assessment.

Air Pollutants↗