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M M Walther

Publications and source records attributed to M M Walther.

At least 19 recordsLinked to original sources
PubMed2001

Recent advances in genetics, diagnosis, localization, and treatment of pheochromocytoma.

Pheochromocytoma is a rare but important tumor of chromaffin cells that is frequently considered in the evaluation of hypertension, arrhythmias, or panic disorder and in the follow-up of patients with particular genetic diseases. This report provides an update about the genetics, neurochemical diagnosis, localization by imaging, and surgical management of pheochromocytoma. Specific mutations of the RET proto-oncogene cause familial predisposition to pheochromocytoma in multiple endocrine neoplasia type II, and mutations in the von Hippel-Lindau tumor suppressor gene cause familial disposition to pheochromocytoma in von Hippel-Lindau disease. Recent findings demonstrating extraordinarily high sensitivity of plasma levels of metanephrines for detecting pheochromocytoma have led to an algorithm for clinical diagnostic steps. Nuclear imaging approaches, such as(123) I-metaiodobenzylguanidine scintigraphy and 6-[(18) F]fluorodopamine positron emission tomography, enhance both diagnosis and localization of the tumor, as described in an algorithm for patients with positive biochemical test results. Since pheochromocytoma is often benign, surgical resection by laparoscopic adrenalectomy can be curative. Areas requiring further work include determining appropriate follow-up of patients with familial pheochromocytoma, elucidating the bases for phenotypic differences, improving both specificity and sensitivity of biochemical tests, optimizing cost-effectiveness of diagnostic imaging, and testing the risk for tumor recurrence after partial adrenalectomy.

Adrenal Gland Neoplasms↗
PubMed2001

Partial adrenalectomy in patients with multiple adrenal tumors.

Most adrenal tumors are found incidentally and appear as small solitary nodules on abdominal imaging. Occasionally, work-up demonstrates multifocal or bilateral adrenal tumors. Certain patients are predisposed to multiple lesions, such as those with hereditary forms of pheochromocytoma as seen in von Hippel-Lindau disease, multiple endocrine neoplasia type II, and von Recklinghausen's disease. Partial rather than total adrenalectomy should be considered for these patients in an attempt to preserve endogenous adrenocortical function. Partial adrenalectomy has also been used to resect other types of adrenal tumors, especially in patients with a solitary adrenal gland. A discussion of the indications for partial adrenalectomy and of the surgical technique follows.

Adenoma↗
PubMed2001

Early identification of patients with von Hippel-Lindau disease at risk for pheochromocytoma.

von Hippel-Lindau disease (VHL) is an autosomal dominant familial syndrome that predisposes to the formation of tumors in multiple organ systems, including adrenal and extra-adrenal pheochromocytomas. However, fewer than 30% of VHL families develop pheochromocytomas. In recent years, this clinical heterogeneity has been correlated with missense mutations. The VHL patient requires vigilant, lifelong biochemical and radiographic screening for pheochromocytoma. Half of VHL pheochromocytomas present bilaterally, and there is a high incidence of recurrence after surgery. Because of the morbidity of bilateral total adrenalectomy with subsequent steroid replacement therapy, the recent therapeutic trend has been toward observation and minimally invasive adrenal-sparing procedures.

Adrenal Gland Neoplasms↗
PubMed2001

Intraoperative ultrasound during renal parenchymal sparing surgery for hereditary renal cancers: a 10-year experience.

PURPOSE: We review our 10-year experience with intraoperative ultrasound during renal parenchymal sparing surgery in patients with hereditary renal cancers. MATERIALS AND METHODS: Between 1991 and 2000, 68 nephron sparing procedures were performed on 26 women and 27 men, all but 1 of whom had a hereditary predisposition to renal cancer, for example von Hippel-Lindau, hereditary papillary renal cancer. Intraoperative ultrasound was performed after the surgeon removed all visible or palpable lesions. High frequency transducers (7 MHz.) and color Doppler were used in all cases. Lesions were characterized as simple cysts, complex cysts or solid masses, and were recorded on a map. RESULTS: A total of 935 lesions (mean 12.8 lesions per kidney) were removed in 68 nephron sparing operations performed on 53 patients. Of these lesions 870 were removed without while 65 required intraoperative ultrasound. In 17 of 68 (25%) procedures intraoperative ultrasound identified renal cancers that were not detectable by the surgeon. Mean tumor size of ultrasound detected lesions was 1.0 cm. (range 2 mm. to 4 cm.). Of the 32 cystic lesions identified by intraoperative ultrasound 5 contained renal carcinoma, and 29 of the 33 solid renal masses were renal cell carcinomas. During reoperations ultrasound enabled the surface of the kidney to be evaluated even when it was inaccessible due to scar tissue or adherent perinephric fat. CONCLUSIONS: Intraoperative ultrasound can be performed after all visible lesions have been removed and identifies additional tumors in 25% of patients with hereditary renal cancer, thus ensuring that as many tumors as possible have been removed during renal parenchymal sparing surgery.

Carcinoma, Renal Cell↗
PubMed2001

Pheochromocytomas in von Hippel-Lindau syndrome and multiple endocrine neoplasia type 2 display distinct biochemical and clinical phenotypes.

This study examined the mechanisms linking different biochemical and clinical phenotypes of pheochromocytoma in multiple endocrine neoplasia type 2 (MEN 2) and von Hippel-Lindau (VHL) syndrome to underlying differences in the expression of tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamine synthesis, and of phenylethanolamine N-methyltransferase (PNMT), the enzyme that converts norepinephrine to epinephrine. Signs and symptoms of pheochromocytoma, plasma catecholamines and metanephrines, and tumor cell neurochemistry and expression of TH and PNMT were examined in 19 MEN 2 patients and 30 VHL patients with adrenal pheochromocytomas. MEN 2 patients were more symptomatic and had a higher incidence of hypertension (mainly paroxysmal) and higher plasma concentrations of metanephrines, but paradoxically lower total plasma concentrations of catecholamines, than VHL patients. MEN 2 patients all had elevated plasma concentrations of the epinephrine metabolite, metanephrine, whereas VHL patients showed specific increases in the norepinephrine metabolite, normetanephrine. The above differences in clinical presentation were largely explained by lower total tissue contents of catecholamines and expression of TH and negligible stores of epinephrine and expression of PNMT in pheochromocytomas from VHL than from MEN 2 patients. Thus, mutation-dependent differences in the expression of genes controlling catecholamine synthesis represent molecular mechanisms linking the underlying mutation to differences in clinical presentation of pheochromocytoma in patients with MEN 2 and the VHL syndrome.

Adolescent↗
PubMed2001

Parenchymal sparing surgery in patients with hereditary renal cell carcinoma: 10-year experience.

PURPOSE: von Hippel-Lindau disease, hereditary papillary renal cell carcinoma, the Birt-Hogg-Dubé syndrome and familial renal oncocytoma are familial renal tumor syndromes. These hereditary disorders are noteworthy for the development of multiple bilateral renal tumors and the risk of new tumors throughout life. One management strategy is observation of solid renal tumors until reaching 3 cm, then performing parenchymal sparing surgery. We present a 5-year update on our experience. MATERIALS AND METHODS: From May 1988 to October 1998, 49 patients with hereditary renal cell carcinoma, including von Hippel-Lindau disease in 44, hereditary papillary renal cell carcinoma in 4 and the Birt-Hogg-Dubé syndrome in 1, and 1 with familial renal oncocytoma underwent exploration to attempt renal parenchymal sparing surgery. Patients were followed prospectively with periodic screening for recurrence, metastasis and loss of renal function. Median followup was 79.5 months (range 0.7 to 205). RESULTS: A total of 50 patients underwent 71 operations resulting in unilateral nephrectomy in 6, bilateral nephrectomy in 1 and partial nephrectomy in 65, with 1 to 51 tumors removed from each kidney (mean 14.7). Mean patient age was 39.5 years (range 18 to 70). Of the 65 (40%) partial nephrectomies 26 were performed with cold renal ischemia. Mean blood loss was 2.9 +/- 0.5 l (range 0.15 to 23). Postoperative complications included renal atrophy in 3 patients. Mean preoperative serum creatinine was 1.05 +/- 0.03 mg/dl (range 0.6 to 1.8), and postoperative creatinine was 1.06 +/- 0.04 mg/dl (range 0.6 to 2.0). No patient who underwent renal parenchymal sparing surgery required renal replacement therapy. Metastatic disease developed in 1 patient with a 4.5 cm renal tumor. CONCLUSIONS: Parenchymal sparing surgery with a 3 cm threshold in patients with hereditary renal cancer appears to be an effective therapeutic option to maximize renal function while minimizing the risk of metastatic disease.

Adolescent↗
PubMed2001

Lack of retroperitoneal lymphadenopathy predicts survival of patients with metastatic renal cell carcinoma.

PURPOSE: Patients with metastatic renal cell carcinoma have a reported 5-year survival of 0% to 20%. The ability to predict which patients would benefit from nephrectomy and interleukin-2 (IL-2) therapy before any treatment is initiated would be useful for maximizing the advantage of therapy and improving the quality of life. MATERIALS AND METHODS: A retrospective analysis of the x-rays and charts of patients treated at the National Institutes of Health Surgery Branch between 1985 and 1996, who presented with metastatic renal cancer beyond the locoregional area and the primary tumor in place, was performed. Preoperative computerized tomography or magnetic resonance imaging, or radiological reports if no scans were available, were used to obtain an estimate of the volume of retroperitoneal lymphadenopathy. Operative notes were used to evaluate whether all lymphadenopathy was resected or disease left in situ, or if any extrarenal resection, including venacavotomy, was performed. Mean survival rate was calculated from the time of nephrectomy to the time of death or last clinical followup. If patients received IL-2 therapy, the response to treatment was recorded. Mean survival and response rate for IL-2 were compared among patients in 3 separate analyses. Patients without preoperatively detected lymphadenopathy were compared with those with at least 1 cm.3 retroperitoneal lymphadenopathy. Also, the patients who had detectable lymphadenopathy were divided into subgroups consisting of all resected, incompletely resected, unresectable and unknown if all disease was resected. Each subgroup was compared with patients without detectable preoperative lymphadenopathy. Patients with less than were compared to those with greater than 50 cm.3 retroperitoneal lymphadenopathy. Patients undergoing extrarenal resection at nephrectomy (complex surgery) due to direct invasion of the tumor into another intra-abdominal organ were compared with those undergoing radical nephrectomy alone, regardless of lymph node status. Statistical analysis was done with the Mantel-Cox test for comparison of survival on Kaplan-Meier curves and with Fisher's exact test for response rates for IL-2. RESULTS: A total of 154 patients with metastatic renal cell carcinoma underwent cytoreductive nephrectomy as preparation for IL-2 based regimens. There were 82 patients with metastatic renal cell carcinoma and no preoperative retroperitoneal lymphadenopathy who survived longer (median 14.7 months) than the 72 with lymphadenopathy (median 8.5, p = 0.0004). Patients with incompletely resected, unresectable or an unknown volume resected had decreased survival compared to those with no retroperitoneal lymphadenopathy. A multivariate analysis of survival was performed evaluating the known prognostic indicators, performance status and tumor burden, as represented by the number of organs involved with metastases, and the new prognostic factor, lymphadenopathy. Lymphadenopathy was more closely associated with survival than performance status, and appeared to be a new prognostic variable. Patients with and without retroperitoneal lymphadenopathy at initial presentation had similar rates for treatment with IL-2 (54% for both groups). Of the 82 patients with no lymphadenopathy 11 (13%) had long-term survival greater than 5 years. Of the 6 complete responses to IL-2, 5 occurred in this group. Only 1 other patient with incompletely resected retroperitoneal lymphadenopathy survived longer than 5 years. No significant difference in survival was seen between patients who did or did not undergo complex surgery. CONCLUSIONS: Patients who presented with metastatic renal cancer and retroperitoneal lymphadenopathy had a shorter survival than those with no detectable retroperitoneal lymphadenopathy. It is warranted to continue to perform complex extrarenal resection during nephrectomy since no significant difference in the response rate for IL-2 or mean survival compared with those of patients undergoing nephrectomy alone is currently detectable.

Adult↗
PubMed2001

An articulating retractor holder to facilitate laparoscopic adrenalectomy and nephrectomy.

PURPOSE: Minimally invasive surgical approaches to renal and adrenal tumors have gained increasing use. The addition of robotic assistance and mechanical devices has decreased the number of assistants required for these often long cases. We describe an articulating arm retractor holder to aid in liver and spleen retraction during laparoscopic surgery. MATERIALS AND METHODS: The articulating retractor holder consists of 4 components, including a base rod, flexible extension arm, stainless steel precision clamp and table attachment. During laparoscopy the abdomen is visualized using standard approaches. The articulating retractor holder is clamped to the table via the base rod and brought into the surgical field using sterile technique. A retractor is placed intracorporeally to elevate the liver or spleen and the handle is secured in place using the precision clamp. RESULTS: The articulating retractor holder was used in all right and approximately 50% of left laparoscopic cases. Adequate visualization was obtained in all patients. There were no device failures or retractor related complications. CONCLUSIONS: The articulating retractor holder is a useful tool to aid in laparoscopic retraction that should be added to the urologist armamentarium.

Adrenal Gland Neoplasms↗
PubMed2001

Retroperitoneoscopic-guided radiofrequency ablation of renal tumors.

OBJECTIVE: Minimally invasive approaches to the management of renal tumors are being studied intensively in urology. Herein, we describe the use of multiple organ-sparing techniques for the management of tumors in a patient with von Hippel Lindau disease (VHL). MATERIALS AND METHODS: A 42 year-old woman with VHL underwent a right partial adrenalectomy and a left renal radiofrequency ablation (RFA) of two renal tumors. RESULTS: A 2.2 cm solitary right adrenal pheochromocytoma was resected using a transperitoneal approach. A retroperitoneal approach to the left kidney was performed and RFA of the two renal tumors completed using sonographic guidance. On the 5-month follow-up CT scan, there was no evidence of residual adrenal tumors and both renal lesions lacked contrast enhancement. No complications occurred during the post-operative recovery. CONCLUSIONS: Multiple organ-ablative laparoscopic procedures may be performed in a single sitting. Laparoscopic partial adrenalectomy is an effective technique in patients with bilateral tumors or a familial syndrome predisposing to multiple adrenal tumors. Further study of renal RFA is required to assess the long-term durability of the procedure.

Adrenal Gland Neoplasms↗
PubMed2000

Suramin administration is associated with a decrease in serum calcium levels.

Suramin has been shown to have an effect on bone resorption in in vitro models. It is not clear if a similar effect is seen in patients treated with suramin. The clinical effect of suramin treatment on total serum calcium was examined in two groups of patients with hormone-refractory prostate cancer. In all, 28 patients in group 1 were examined within 2 weeks before and 2 weeks after suramin treatment and 72 patients in group 2 were examined within 2 weeks before, during, and after treatment with suramin. In addition, calcium controls spiked with suramin were run in three different commercially available assays for evaluation of the effect of suramin dose on calcium determination. Group 1 patients showed a decrease in serum calcium after treatment with suramin. The mean uncorrected serum calcium level was 2.29 +/- 0.025 mmol/l before treatment and 2.09 +/- 0.025 mmol/l after treatment (P < 0.0001, paired Wilcoxon test). The mean serum calcium value corrected for albumin was 2.33 +/- 0.02 mmol/l before treatment and 2.24 +/- 0.02 mmol/l after treatment (P = 0.0022, paired Wilcoxon test). Group 2 patients also displayed a decrease in serum calcium after treatment with suramin. The mean baseline value was 2.23 mmol/l (median 2.26 mmol/l, range 1.20-2.54 mmol/l). The mean level of serum calcium corrected for albumin as determined at the end of treatment was 2.14 mmol/l (median 2.16 mmol/l, range 0.98 2.46 mmol/l). In all, 48 patients for whom pre- and post-treatment values were available for analysis displayed a median calcium decrease of 0.09 mmol/l (P = 0.0005, Wilcoxon signed-rank test for the null hypothesis of no change). For 68 patients in group 2, data on serial serum calcium measurements during treatment were available for analysis. A projected median decrease in serum calcium of 0.06 mmol/l (range 0.43 to 0.72 mmol/l) over an 8-week interval of suramin therapy was found. Overall, 47 of the 68 slopes were negative (P = 0.0022, Wilcoxon signed-rank test). Nine patients were treated with suramin for less than 6 weeks. These patients' calcium levels were significantly higher than those of 50 patients treated for longer periods (median value 2.24 versus 2.16 mmol/l, P = 0.035, Wilcoxon rank-sum test). No correlation was found between suramin dose and calcium level using the Kodak Ektachem, Hitachi 914, or Synchron Clinical System CX3 method. In conclusion, suramin treatment was consistently associated with decreases in serum calcium in two groups of patients with hormone-refractory cancer. Suramin placed in calcium controls did not affect calcium determination using three commercially available methods.

Anti-Inflammatory Agents↗
PubMed2000

Histopathology and molecular genetics of multiple cysts and microcystic (serous) adenomas of the pancreas in von Hippel-Lindau patients.

Microcystic adenoma and cysts of the pancreas occur sporadically or as a part of von Hippel-Lindau (VHL) disease. The pathology of pancreatic cystic disease in VHL patients has not been well characterized. Furthermore, it is presently unknown whether the alteration of the VHL gene is responsible for the development of the entire spectrum of pancreatic serous cystic lesions. We performed a histopathological analysis of 21 cysts and 98 microcystic adenomas in nine VHL patients with a known germline mutation. In addition, PCR-amplified DNA from 27 pancreatic cystic lesions in three informative patients was studied for allelic deletions with polymorphic markers spanning the VHL gene locus. In all patients, pancreatic lesions were multiple: 21 benign serous cysts, 63 microscopic microcystic adenomas (size <0.4 cm), and 35 macroscopic microcystic adenomas (size >0.5 cm). The average number of lesions per patient was 2.1 benign cysts (range, 0-8), 7.7 (1-37) microscopic microcystic adenomas, and 3 (0-21) macroscopic microcystic adenomas. All lesions showed similar histology and contained prominent fibrous stroma, clear and/or amphophilic, glycogen-rich epithelial cells, endothelial and smooth muscle cells. VHL deletions were detected in all types of pancreatic cystic lesions. The presence of VHL gene allelic deletions in the spectrum of multifocal pancreatic cystic lesions provides direct molecular evidence of their neoplastic nature and integral association with VHL disease. The histopathological and molecular data establish a serous cyst-microcystic adenoma continuum in the development of pancreatic cystic neoplasia in VHL disease.

Adenoma↗