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Biomedical subjects

Herbert Chen

Publications and source records attributed to Herbert Chen.

65 records · Page 4Linked to original sources
PubMed2002

Palliative thyroidectomy for malignant lymphoma of the thyroid.

BACKGROUND: Current treatment of malignant lymphoma of the thyroid consists of chemotherapy and external beam radiation. The diagnosis can routinely be made by fine-needle aspiration, obviating the need for surgery. However, a significant number of patients present with symptoms of obstruction, necessitating thyroidectomy for palliation. METHODS: To determine the outcomes of patients with malignant thyroid lymphoma after palliative thyroidectomy, we reviewed our experience. Between 1980 and 2001, 27 patients with thyroid lymphoma and symptoms or signs of airway and/or esophageal obstruction were evaluated at 1 of 3 academic institutions. RESULTS: The mean age of the patients was 66 +/- 3 years, and the majority was female. Patients presented with symptoms of dyspnea/stridor (30%), dysphagia/pain (30%), or impending airway obstruction (40%). All underwent palliative surgery. In addition to surgery, 10 patients had combined chemo- and radiotherapy, 10 had radiotherapy alone, and 4 had only chemotherapy. Symptom-free survival after palliative surgery was determined by Kaplan-Meier analysis. The mean actuarial symptom-free survival of patients with symptomatic, malignant thyroid lymphoma was 10 years (95% confidence interval, 7.67 to 12.33 years). CONCLUSIONS: Patients with malignant lymphoma of the thyroid can present with obstructive symptoms requiring palliative intervention. In this group of patients, thyroidectomy can be associated with good long-term palliation and low morbidity.

Aged↗
PubMed2002

Primary thyroid lymphoma: can the diagnosis be made solely by fine-needle aspiration?

BACKGROUND: Primary malignant lymphoma of the thyroid accounts for <5% of all thyroid malignancies and is primarily treated with chemotherapy and external beam radiation. With the advent of modern immunophenotypic analyses, fine-needle aspiration (FNA) can potentially obviate the need for surgical procedures. METHODS: To investigate the utility of FNA, data from 23 consecutive patients with primary malignant thyroid lymphoma evaluated at the Johns Hopkins Hospital from July 1985 to April 2000 were analyzed. RESULTS: Patients were categorized into two groups: those diagnosed before 1993 (group 1, n = 12) and those diagnosed after 1993 (group 2, n = 11). Although patients in group 1 were slightly older, there were no other differences between the groups with regard to sex, tumor grade, or tumor stage. Although no patient in group 1 was successfully diagnosed by FNA alone, seven patients (63%) in group 2 were diagnosed solely by FNA (P =.019, chi(2) analysis). Therefore, all 12 patients in group 1, but only 4 of 11 patients in group 2, required open surgical biopsy. CONCLUSIONS: Primary thyroid lymphoma is an uncommon malignancy usually treated nonsurgically once the diagnosis is established. In most patients with malignant lymphoma of the thyroid, FNA, should obviate the need for open surgical biopsy.

Adult↗
PubMed2002

Activation of the ras/raf-1 signal transduction pathway in carcinoid tumor cells results in morphologic transdifferentiation.

BACKGROUND: Recent studies of neuroendocrine tumor cell lines suggest that ras/raf-1 activation could be detrimental to tumorigenesis. The mechanism by which it alters neuroendocrine tumor cells is unclear. We hypothesize that activation of the ras/raf signal transduction pathway may alter gastrointestinal carcinoid cells by inducing morphologic transdifferentiation. METHODS: Pancreatic carcinoid (BON) cells were transduced in a stable manner with an estrogen inducible raf-1 fusion protein (creating "BON-raf cells"). BON and BON-raf cells were then treated with either control or 1 micromol/L estradiol (E2). Western blots were used to confirm the phosphorylation of extracellular signal-regulated kinase 1/2. Morphologic changes were evaluated using light and electron microscopy. RESULTS: Western blots using antibodies against phosphorylated and unphosphorylated extracellular signal-regulated kinase 1/2. confirmed that phosphorylation was only present in the BON-raf E2 cells. BON cells treated with control and E2 and BON-raf cells treated with control all looked identical in culture. After treatment with E2 to induce raf-1, the BON-raf cells underwent dramatic morphologic changes. Under light and electron microscopy the cells became flatter and developed much sharper cellular borders mimicking cellular differentiation. CONCLUSIONS: Activation of the ras/raf-1 signal transduction pathway leads to prominent phenotypic changes that resemble differentiation of gastrointestinal carcinoid cells in vitro.

Carcinoid Tumor↗
PubMed2002

Long-term follow-up of patients with tertiary hyperparathyroidism treated by resection of a single or double adenoma.

OBJECTIVE: To determine whether patients with tertiary hyperparathyroidism due to single- or two-gland disease undergoing limited resection have similar long-term outcomes compared with patients with hyperplasia undergoing subtotal or total parathyroidectomy. SUMMARY BACKGROUND DATA: Tertiary hyperparathyroidism occurs in less than 2% of patients after renal transplantation. Approximately 30% of these cases are caused by one or two hyperfunctioning glands. Nevertheless, the standard operation for this disease has been subtotal or total parathyroidectomy with autotransplantation. METHODS: Seventy-one patients underwent surgery for tertiary hyperparathyroidism. At the time of surgery, 19 patients who had a single or double adenoma underwent limited resection of the enlarged glands only (adenoma group). The remaining 52 patients with three- or four-gland hyperplasia had subtotal or total parathyroidectomy with implantation (hyper group). Long-term cure rates between the two groups were compared. RESULTS: In the adenoma group, 7 patients had a single adenoma and 12 underwent resection of a double adenoma. In the hyper group, 49 patients had subtotal and 3 had total parathyroidectomies. After surgery, 70 of 71 patients (99%) were cured of their hypercalcemia. The incidence of postoperative transient hypocalcemia was significantly higher in the hyper group (27% vs. 5%). No patients in either group had permanent hypocalcemia requiring long-term supplementation. With up to 16 years of follow-up, there have been no recurrences in the adenoma group, whereas three patients (6%) in the hyper group have had recurrent or persistent hyperparathyroidism. CONCLUSIONS: Patients with tertiary hyperparathyroidism who underwent limited resection of a single or double adenoma only had equivalent long-term cure rates compared with patients undergoing more extensive resections. Therefore, the authors recommend in patients with tertiary hyperparathyroidism and enlargement of only one or two parathyroid glands that the resection be limited to these abnormal glands only.

Adenoma↗
PubMed2002

Radioguided parathyroidectomy via VATS combined with intraoperative parathyroid hormone testing: the surgical approach of choice for patients with mediastinal parathyroid adenomas?

Despite the excellent results with bilateral exploration, minimally invasive parathyroidectomy has become the procedure of choice for patients with hyperparathyroidism in which a single parathyroid lesion can be localized preoperatively. In this article, we discuss a patient who presented with primary hyperparathyroidism for the first time and had a Tc-99m sestamibi scan to localize a single parathyroid lesion in the left, anterior mid-mediastinum. We subsequently performed a radioguided parathyroidectomy via video-assisted thoracoscopic surgery (VATS) to resect this parathyroid adenoma and used intraoperative parathyroid hormone (PTH) testing to confirm cure and avoid neck exploration. We concluded that radioguided parathyroidectomy via VATS combined with intraoperative PTH testing is an effective approach for patients with primary hyperparathyroidism and mediastinal parathyroid lesions, and perhaps should be the technique of choice.

Adenoma↗
PubMed2001

Do future general surgery residents have adequate exposure to endocrine surgery during medical school?

During their general surgical rotations, medical students should ideally have exposure to a wide breadth of surgical procedures, especially if they are interested in pursuing surgical careers. To determine their exposure to endocrine surgery during medical school, we surveyed students from more than 20 medical schools who interviewed for general surgery residency positions at our institution over a 2-year period. Questions focused on the total number of index surgical procedures observed during all of their medical school education. Of 211 surveys sent, 146 were returned (66%). The mean age of the students was 26.0 +/- 0.3 years, and 21% were women. The average times spent on general surgery and surgery subspecialty rotations during medical school were 11.1 +/- 0.6 weeks and 7.6 +/- 0.4 weeks, respectively. The mean number of thyroidectomies (2.8 +/- 0.3), parathyroidectomies (1.9 +/- 0.3), and adrenalectomies (0.5 +/- 0.1) observed by the medical students were significantly lower than operations such as mastectomies (9.4 +/- 0.3), coronary bypass surgeries (8.7 +/- 1.4), and laparoscopic cholecystectomies (10.0 +/- 0.7). Furthermore, of these 146 future surgical residents, 34% failed to observe a single thyroid resection, 42% did not see a parathyroidectomy, and 65% failed to see an adrenalectomy. In conclusion, future general surgery residents seem to observe a wide variety of surgical cases, but most have little or no exposure to endocrine surgery. This paucity of exposure may have significant educational and career ramifications.

Adrenalectomy↗
PubMedDate not supplied

Calciphylaxis in the absence of end-stage renal disease.

OBJECTIVE: To report a case of calciphylaxis in the absence of renal failure in a patient with secondary hyperparathyroidism and low calcium/phosphorus product, in whom total parathyroidectomy resulted in relief of pain and healing of ulcerations. METHODS: We present the clinical, laboratory, and pathologic findings in a 62-year-old woman with calciphylaxis in the absence of end-stage renal disease. RESULTS: A 62-year-old woman presented with painful nonhealing bilateral calf ulcerations. Pathology examination of tissue specimens from surgical débridement revealed intravascular calcification, consistent with calciphylaxis. Laboratory investigation revealed normal renal function; however, hypocalcemia and hypophosphatemia were present--a corrected serum calcium level of 7.5 mg/dL (normal, 8.5 to 10.2) and a serum phosphorus value of 1.0 mg/dL (normal, 2.5 to 4.5). These abnormalities were likely due to vitamin D deficiency, evidenced by a 25-hydroxyvitamin D level of 14 ng/mL, which provoked an elevation of the serum parathyroid hormone (PTH) concentration, documented by an intact PTH of 213 pg/mL (normal, 15 to 65) and a whole PTH (1-84 PTH) of 70.6 pg/mL (normal, 7 to 36). Her quality of life was severely impaired, not only by the ulcerations but also by intractable pain that necessitated epidural analgesia during the hospitalization. The patient underwent total parathyroidectomy and transcervical thymectomy, with cryopreservation of parathyroid tissue. One year after the parathyroidectomy, the patient had no recurrence of calciphylaxis. CONCLUSION: This case suggests that despite the potential complex pathophysiologic aspects of calciphylaxis, even in the absence of both renal failure and an elevated calcium/phosphorus product, early parathyroidectomy in patients with appreciably increased PTH levels may improve wound healing and diminish pain.

Calciphylaxis↗