Ganglioneuromas and renal anomalies are induced by activated RET(MEN2B) in transgenic mice.
Multiple endocrine neoplasia type 2B (MEN2B) is an autosomal dominant syndrome characterized by the development of medullary thyroid carcinoma, pheochromocytomas, musculoskeletal anomalies and mucosal ganglioneuromas. MEN2B is caused by a specific mutation (Met918-->Thr) in the RET receptor tyrosine kinase. Different mutations of RET lead to other conditions including MEN2A, familial medullary thyroid carcinoma and intestinal aganglionosis (Hirschsprung disease). Transgenic mice were created using the dopamine beta-hydroxylase promoter to direct expression of RET(MEN2B) in the developing sympathetic and enteric nervous systems and the adrenal medulla. DbetaH-RET(MEN2B) transgenic mice developed benign neuroglial tumors, histologically identical to human ganglioneuromas, in their sympathetic nervous systems and adrenal glands. The enteric nervous system was not affected. The neoplasms in DbetaH-RET(MEN2B) mice were similar to benign neuroglial tumors induced in transgenic mice by activated Ras expression under control of the same promoter. Levels of phosphorylated MAP kinase were not increased in the RET(MEN2B)-induced neurolglial proliferations, suggesting that alternative pathways may play a role in the pathogenesis of these lesions. Transgenic mice with the highest levels of DbetaH-RET(MEN2B) expression, unexpectedly developed renal malformations analogous to those reported with loss of function mutations in the Ret gene. (+info)
The elevated serum alkaline phosphatase--the chase that led to two endocrinopathies and one possible unifying diagnosis.
A 39-year-old Chinese man with hypertension being evaluated for elevated serum alkaline phosphatase (SAP) levels was found to have an incidental right adrenal mass. The radiological features were characteristic of a large adrenal myelolipoma. This mass was resected and the diagnosis confirmed pathologically. His blood pressure normalised after removal of the myelolipoma, suggesting that the frequently observed association between myelolipomas and hypertension may not be entirely coincidental. Persistent elevation of the SAP levels and the discovery of hypercalcaemia after surgery led to further investigations which confirmed primary hyperparathyroidism due to a parathyroid adenoma. The patient's serum biochemistry normalised after removal of the adenoma. The association of adrenal myelolipoma with primary hyperparathyroidism has been reported in the literature only once previously. Although unconfirmed by genetic studies this association may possibly represent an unusual variation of the multiple endocrine neoplasia type 1 syndrome. (+info)
A possible contributory role of BK virus infection in neuroblastoma development.
The tumor suppressor protein p53 is aberrantly localized to the cytoplasm of neuroblastoma cells, compromising the suppressor function of this protein. Such tumors are experimentally induced in transgenic mice expressing the large tumor (T) antigen of polyomaviruses. The oncogenic mechanisms of T antigen include complex formation with, and inactivation of, the tumor suppressor protein p53. Samples from 18 human neuroblastomas and five normal human adrenal glands were examined. BK virus DNA was detected in all neuroblastomas and none of five normal adrenal glands by PCR. Using DNA in situ hybridization, polyomaviral DNA was found in the tumor cells of 17 of 18 neuroblastomas, but in none of five adrenal medullas. Expression of the large T antigen was detected in the tumor cells of 16 of 18 neuroblastomas, but in none of the five adrenal medullas. By double immunostaining BK virus T antigen and p53 was colocalized to the cytoplasm of the tumor cells. Immunoprecipitation revealed binding between the two proteins. The presence and expression of BK virus in neuroblastomas, but not in normal adrenal medulla, and colocalization and binding to p53, suggest that this virus may play a contributory role in the development of this neoplasm. (+info)
Neuroblastoma metastatic to the liver in infants.
Four infants are described who presented with rapid enlargement of the liver. This was found to be due to neuroblastoma which had metastasized to the liver; the condition was associated with high levels of urinary vanillylmandelic acid (VMA). In 3 infants the primary tumour was in the adrenal gland and in one it was not identified. One infant died after laparotomy and 2 infants survive disease free with normal VMA levels, one after adrenalectomy and hepatic irradiation and one after a short course of chemotherapy. The fourth patient responded initially to hepatic irradiation and chemotherapy, but relapsed 2 years later with recurrent disease; at the same time the VMA level which had been normal, again rose. The importance of screening for an abnormal VMA level in any infant with a rapidly enlarging liver in order to obtain an early diagnosis is stressed. Careful follow-up, with serial VMA estimations, is essential to detect recurrent disease. The prognosis for some infants with this distribution of neuroblastoma which has metastasized to the liver, but not to the bones or oribt, is good. (+info)
Rat sarcoma model supports both "soil seed" and "mechanical" theories of metastatic spread.
Following injection into the portal venous or vena caval systems, tumour cells are held up almost exclusively in the liver or lung respectively, and subsequent outgrowth of tumour only occurs in these organs. Following systemic arterial injection, cells are distributed, and subsequently grow, in a variety of organs. However, the adrenal gland supports tumour growth from much fewer cells than the lung, and this is partly due to the fact the rate of tumour cell loss in the initial 48 h is very high in the latter compared to the former organ. (+info)
Combined liver-spleen-kidney scintigraphy and subsequent subtraction of the kidney scintiphotograph in the evaluation of displaced kidney.
The displacement of kidney was studied by using the combined liver-spleen-kidney scintigraphy and the subsequent subtraction of the kidney scintiphotograph to leave the liver-spleen scintiphotograph alone. A suprarenal mass was shown as cold spot between the liver and right kidney on the combined study. When the liver scintiphotograph and kidney scintiphotograph were over-lapped and the differential diagnosis was difficult, the subsequent subtraction of the kidney scintiphotograph was useful in the diagnosis of the enlarged liver. (+info)
Multiple endocrine neoplasia type 2A with the identical somatic mutation in medullary thyroid carcinoma and pheochromocytoma without germline mutation at the corresponding site in the RET proto-oncogene.
A germline mutation either in exon 10 or 11 of the RET proto-oncogene is found in the majority of patients with multiple endocrine neoplasia type 2A (MEN 2A). A 41-year-old female patient was referred for further evaluation of incidentally discovered right adrenal tumor. She had bilateral adrenal pheochromocytomas and medullary thyroid carcinomas detected by endocrinological and radiological examination, and diagnosed as MEN 2A. Molecular genetic testing of the RET exons 10 and 11 exhibited the identical somatic missense mutation at codon 634 in both tumors but did not confirm germline mutations in the corresponding sites. Possible mechanisms for tumorigenesis in this patient are discussed. (+info)
Mercury intoxication presenting with hypertension and tachycardia.
An 11 year old girl presented with hypertension and tachycardia. Excess urinary catecholamine excretion suggested phaeochromocytoma but imaging studies failed to demonstrate a tumour. Other symptoms included insomnia and weight loss, and she was found to have a raised concentration of mercury in blood and urine. Mercury intoxication should be considered in the differential diagnosis of hypertension with tachycardia even in patients presenting without the skin lesions typical of mercury intoxication and without a history of exposure. (+info)