Encapsulation status of papillary thyroid microcarcinomas is associated with the risk of lymph node metastases and tumor multifocality.

The management of papillary microcarcinoma (PMC) of the thyroid is controversial, especially after partial thyroid resection for benign thyroid disease. In order to detect prognostic factors for PMC, we analyzed 116 patients with PMC for encapsulation status and lymph node metastases. Between 10/1992 and 12/2010, 116 patients with PMC have been operated in our department (87 females, 29 males, median age 49 years). Eighty per cent of PMCs were diagnosed postoperatively. Seventy-six patients (66%) received a more extended resection with either thyroidectomy, near total thyroidectomy, or Dunhill operation either primarily or after completion operation, whereas 40 patients (34%) had only partial resection. Fifty patients (43%) received radioiodine (RIA) ablation. Lymph node metastases were found in 21 patients (18%). Univariate analysis showed four risk factors to be significantly associated with the risk of lymph node metastasis (p<0.05): male gender, younger age, age group<50 years and nonencapsulation of the tumor. Multivariate analysis demonstrated statistical significance for gender and tumor capsulation status. The tumor capsulation status also correlated with tumor multifocality. Our data show that the risk of lymph node metastases is significantly higher in partially or nonencapsulated PMC than in encapsulated specimens. We therefore suggest that the WHO classification should be extended to a compulsory notification of the encapsulation status in PMC.

Coincidence of primary hyperparathyroidism and nonmedullary thyroid carcinoma.

The incidence of primary hyperparathyroidism (pHPT) combined with nonmedullary thyroid carcinoma (NMTC) has been reported between 2-13%. To date, it remains controversial whether these 2 pathologies occur coincidental or are caused by specific risk factors or genetic changes. The aim of this study was to evaluate the clinical and histological characteristics of NMTC associated with pHPT. We reviewed prospective database records of 1 464 unselected, consecutive patients who were treated for pHPT in our institution between 1986 and 2012 and identified 41 NMTC (2.8%). The collective consisted of 35 papillary (PTC) and 6 follicular (FTC) thyroid carcinomas. Our collective of 41 NMTC including 34 single adenomas and 7 multiglandular diseases consisted of 33 females and 8 males. Patients with FTC demonstrated significant lower preoperative PTH levels compared to PTC. Interestingly, NMTC were predominantly located on the right side. FTC had significant larger tumors as well as demonstrated increased extrathyroidal growth and lymph node metastases. In 71% pHPT and NMTC were diagnosed synchronously. The comorbidity of pHPT and NMTC occurs in about 3%. As pHPT is often operated by a focal minimally invasive approach, we advocate a mandatory preoperative thyroid ultrasound for all patients with pHPT to be able to identify synchronous thyroid disease.

Loss of PTEN expression in neuroendocrine pancreatic tumors.

PTEN (phosphatase and tensin homologue deleted from chromosome 10) is a well established tumor suppressor gene, which was cloned to chromosome 10q23. PTEN plays an important role in controlling cell growth, apoptosis, cell adhesion, and cell migration. In various studies, a genetic change as well as loss of PTEN expression by different carcinomas has been described. To date, the role of PTEN as a differentiation marker for neuroendocrine tumors (NET) and for the loss of PTEN expression is still unknown. It is assumed that loss of PTEN expression is important for tumor progression of NETs. We hypothesize that PTEN might be used as a new prognostic marker. We report 38 patients with a NET of the pancreas. Tumor tissues were surgically resected, fixed in formalin, and embedded in paraffin. PTEN expression was evaluated by immunohistochemistry and was correlated with several clinical and pathological parameters of each individual tumor. After evaluation of our immunohistochemistry data using a modified Remmele Score, a widely accepted method for categorizing staining results for reports and statistical evaluation, staining results of PTEN expression were correlated with the clinical and pathological parameters of each individual tumor. Our data demonstrates a significant difference in survival with existence of lymph node or distant metastases. Negative patients show a significant better survival compared with positive patients. Furthermore, we show a significant difference between PTEN expression and WHO or TNM classification. Taken together, our data shows a positive correlation between WHO classification and the new TNM classification of NETs, and loss of PTEN expression as well as survival. These results strongly implicate that PTEN might be helpful as a new prognostic factor.

Coincidence of mature cystic teratoma and serotonin-producing neuroendocrine tumor of the ileum.

Mature cystic teratomas are often found in gonadal sites, but are very rarely located extragonadally, for example, in retroperitoneum, mediastinum, central nervous system, lung, or liver. In the literature, only 10 cases of cystic teratoma originating from the diaphragm have been reported. Here, we report for the first time a metachronous occurrence of a benign mature cystic teratoma in the left diaphragm together with a serotonin-producing neuroendocrine tumor of the ileum. The 51-year-old, female patient received a partial resection of the ileum due to a neuroendocrine tumor (pT3N1M0) 4 years ago. Furthermore, she was operated for a benign cystadenoma of the right ovary 3 years ago. In her past medical history, she had an appendectomy in her childhood and a subtotal thyroidectomy 10 years ago. To our knowledge, this is the first report describing the metachronous occurrence of benign mature cystic teratoma in the diaphragm and a highly differentiated neuroendocrine tumor of the ileum. The possible coincidence of both diseases is discussed.

The serum sodium to urinary sodium to (serum potassium)2 to urinary potassium (SUSPPUP) ratio in patients with primary aldosteronism.

BACKGROUND: The aldosterone-to-renin ratio (ARR) is an established diagnostic tool in the screening for primary aldosteronism (PA). However, hormonal determinations are time consuming and expensive. Therefore, we studied the effectiveness of the serum sodium to urinary sodium to (serum potassium)(2) to urinary potassium (SUSPPUP) ratio in the diagnosis of PA. DESIGN: This study included 35 patients with PA, 71 patients with essential hypertension to whom this diagnosis could be excluded, 23 normal subjects without hypertension, and 22 patients with primary adrenal insufficiency. We compared the SUSPPUP ratios with the ARR in these patient groups. RESULTS: We show that the ARR distinguished PA from essential hypertension with a sensitivity of 94.2% and a specificity of 92.1% at a cutoff of 33 (ng L(-1): ng L(-1)). It correlated well with the SUSPPUP ratio. The sensitivity and specificity of SUSPPUP was 88.6% and 85.9% at a cutoff of 5.3 (mmol L(-1))(-1), respectively, and thus not as good as the ARR. CONCLUSIONS: The ARR is a good parameter in the screening for PA. The SUSPPUP ratio is a cheap and rapid tool to assess the extent of mineralocorticoid excess and, therefore, can be offered to more patients. In addition, the application of the SUSPPUP ratio can be extended to patients who suffer from other forms of mineralocorticoid hypertension (e.g. with low aldosterone levels).

Nestin as a marker in the classification of adrenocortical tumors.

Expression of the intermediate filament, nestin, was long believed to be restricted to neuroectodermal stem cells. However, nestin expression has recently been detected in several tumors. Since adrenocortical carcinoma, a tumor entity still very difficult to classify, may gain the ability to aberrantly express neuroectodermal proteins including chromogranin A and synaptophysin, we asked the question whether nestin might also be detected in adrenocortical carcinomas, and if so, whether it might serve as a tool for clinical pathology. Therefore, we studied the expression of nestin in normal adrenal glands, adrenocortical adenomas, and adrenocortical cancers using specific immunohistochemistry and semi-quantitative reverse transcriptase-polymerase chain reaction. Immunostaining was nestin-positive in 1 out of 9 normal adrenal glands (11%), 2 out of 20 adrenocortical adenomas (10%), and 13 out of 16 adrenocortical carcinomas (81%). Expression of nestin mRNA could be detected in all microdissected tissues, independently of their grade of dedifferentiation. We conclude that our findings provide further evidence that nestin, as a marker, is not restricted to neuronal stem cells and nestin expression is worth to be studied in adrenocortical tumors.

Standard-radical vs. function-preserving surgery of benign nodular goiter: a sonographic and biochemical 10-year follow-up study.

BACKGROUND: The necessary extent of thyroid resection in benign nodular goiter is under debate. The aim of our study was to compare the long-term outcome of different thyroid resection modes with special interest in the incidence of recurrent nodules and the use of oral thyroid hormone medication. MATERIALS AND METHODS: We performed a follow-up examination of 109 patients (23 men and 86 women) having been operated for benign nodular goiter at our department 10 years ago. Unilateral resections and function-preserving resections of at least one thyroid lobe were classified as function-preserving (FP). Total thyroidectomy, Dunhill's operation and bilateral subtotal thyroidectomy were rated as standard-radical (STR). On follow-up, we recorded current oral thyroid hormone medication, thyroid function tests and ultrasound of the neck. RESULTS: Seventy-three patients had FP resection (67%), while 36 were STR-operated (33%). The subsequent medical treatment was performed by dedicated endocrinologists (n = 19), internists (n = 11) or primary-care physicians (n = 59). Twenty patients had no medical attendance. Recurrent nodules were found in 13 cases in the FP group (18.6%) vs. 3 cases in the STR group (2.5%; p < 0.001). In both groups, about 80% of patients used thyroid hormone medication 10 years after operation. CONCLUSION: There was no advantage in thyroid function tests nor lesser medication in the FP group. The risk for recurrent nodules was significantly higher in the FP than in the STR-operated patients.

[Localisation of parathyroid glands using planar (99m)Tc-sestamibi scintigraphy. Comparison between subtraction- and dual-phase technique]. / Lokalisation von Nebenschilddrüsenadenomen mit planarer (99m)Tc-Sestamibi-Szintigraphie: Vergleich von Subtraktionsund 2-Phasen-Technik.

AIM: In the context of presurgical localisation of parathyroid adenomas in primary hyper-parathyreoidism (pHPT) using (99m)Tc-sestamibi scintigraphy, subtraction- and dualphase technique are compared with each other and with the surgical findings. PATIENTS, METHODS: Prospectively, 126 patients with pHPT were investigated presurgically. For visualisation of parathyroid adenomas, an image of the thyroid ((99m)Tc-pertechnetat) was subtracted from a perfusion image ((99m)Tc-sestamibi) and 2 h p. i. another image was acquired for identification of retention of activity. Considering both techniques the clinical findings were reported promptly. Retrospectively, the evaluations were presented separately to four experienced raters. RESULTS: In clinical routine for 109 patients correct findings were reported presurgically (87%). From 129 resected parathyroid adenomas 118 were localised correctly (sensitivity 91%, positive predictive value 94%). Concerning the retrospective analysis, in 75% of the cases both techniques provided the correct site, in 14% only the dual-phase technique and in 7% only the subtraction-technique was correct. With the help of the dual-phase technique significantly more investigations were correctly rated than with the help of the subtraction technique (88.7 +/- 3.2% vs. 81.6 +/- 1.2%, p < 0.01, two-sided t-test). CONCLUSION: The presurgical scintigraphic localisation of hyperactive parathyroid glands in pHPT assists minimal invasive surgery serving a high rate of correct findings. According to our data the dual-phase technique seems to be more sensitive than the subtraction technique. In some cases, however, the correct site may only be found using the subtraction technique. For an optimal surgical strategy we suggest the combination of both techniques.

Episodic respiratory failure due to focal epileptic activity.

We report on a patient with a complicated course after surgical abdominal intervention and episodic life threatening respiratory failures successfully treated with carbamazepine after diagnosis of a ponto-medullary lesion in the MRI.

Allelic loss of the retinoblastoma tumor suppressor gene: a marker for aggressive parathyroid tumors?

Allelic loss of the retinoblastoma tumor suppressor gene has recently been shown to be highly specific for parathyroid carcinoma. It has been proposed that this genetic abnormality may have diagnostic and prognostic implications for parathyroid carcinoma, but to date no further studies are available to substantiate these findings. In the present study, three cases of atypical recurrent hyperparathyroidism were examined: a patient with parathyroid carcinoma and an autotransplanted adenoma that progressed into carcinoma, a patient with recurrent juvenile hyperparathyroidism, and a patient with severe recurrent secondary hyperparathyroid disease due to rapidly growing autotransplant. Six pairs each of sporadic parathyroid adenoma and secondary parathyroid disease were also studied for comparison. Allelic losses of RB and D13S71 at 13q14 was found in the parathyroid carcinoma and the corresponding autotransplant that had previously been considered benign tissue and in the case of recurrent juvenile hyperparathyroidism, but not in any of the other tumors. Our findings support the findings of the previous study that RB or 13q loss is specific for parathyroid tumors with increased aggressiveness and might be of clinical significance.

Multiple neuroendocrine tumors of the pancreas associated with pancreas divisum.

Pancreas divisum is the most common congenital anomaly of the pancreas, characterized by missing fusion of the ventral and dorsal pancreatic duct. It may cause pancreatitis, but is rarely associated with malignancy.We report herein for the first time the rare association, in a symptomless patient, of multiple neuroendocrine tumors of the pancreas with pancreas divisum and a failure of the exocrine system. Diagnosis was made incidentally by routine abdominal ultrasound. Laboratory examinations and a fine-needle aspiration revealed the neuroendocrine nature of the tumor. Spleen-preserving left pancreas resection was performed, with evidence of multiple neuroendocrine tumors of the pancreas with the typical histological characteristics. Eighteen months later the patient is still free of tumor burden.

Malignant endocrine tumors in patients with MEN 1 disease.

BACKGROUND: In contrast with multiple endocrine neoplasia type 2, malignancies are of minor importance in multiple endocrine neoplasia type 1 (MEN 1) syndrome. METHODS: The data for 42 patients with MEN 1 syndrome were evaluated. Twelve patients (29%) had 1 or more associated malignancies: malignant gastrinoma (1 patient), neuroendocrine tumors of the thymus (2 patients), neuroendocrine tumors of the lung (3 patients), neuroendocrine tumor of the ileum (1 patient), adrenocortical carcinomas (2 patients), and a combination of neuroendocrine tumors of thymus, lung or pancreas (3 patients). RESULTS: Despite suspected MEN 1 syndrome in 7 patients, malignancies were detected late in 4 patients and could not be resected curatively. The survival rates for 5 years and 10 years after operation of the malignant tumor were 66% +/- 14% (SE) and 33% +/- 15% (SE), respectively. CONCLUSIONS: In patients at risk for the MEN 1 syndrome, genetic screening is indispensable. Gene carriers have to be followed up closely with hormone analysis and routine examination of the thorax, pancreas, and adrenal glands to detect malignancies as early as possible.

Therapeutic strategy of papillary cystic and solid neoplasm (PCSN): a rare non-endocrine tumor of the pancreas in children.

Papillary-cystic and solid neoplasm (PCSN) are rare tumors. Two personal observations and a review of the literature are presented with a total of 44 pediatric patients in addition to a total of 67 published cases in the review of Cohen (Pediatr. Surg. Int. 6 (1991) 128) and Snadjauf (Eur. J. Pediatr. Surg. 9 (1999) 416). Overall, PCSN shows a clear predominance in females and only occasionally occurs in males. Typically they grow to a large tumor mass with minimal symptoms. Their histologic and immunocytologic characteristics cause diagnostic difficulties, especially on frozen sections of small biopsies. The tumors are assumed to origin from pluripotent stem cells and present as tumors of low malignancy with a favorable prognosis. Nevertheless 10 children have been reported to develop metastases, 5 have demonstrated an invasive growth pattern and 4 local recurrence. But only two of the 111 pediatric cases have died from their tumor burden. Treatment of choice is a complete surgical resection, which is true for the primary tumor and for metastases as well as local recurrences. In our 2 patients one had spleen-conserving left pancreatic resection and one mesopancreatectomy with roux-en-y-reconstruction leading to long-term cure. Adjuvant therapy in curative resected patients is unnecessary and does not appear to improve prognosis.

Parathyroid carcinoma: problems in diagnosis and the need for radical surgery even in recurrent disease.

INTRODUCTION: From 1986 to 1999 we operated on 963 patients with primary hyperparathyroidism (pHPT). METHODS AND RESULTS: Parathyroid carcinoma was diagnosed clinically and histologically in four patients (0.4%). In two of these patients diagnosis of parathyroid cancer was delayed by misinterpretation of the histopathology leading to an autotransplantation of malignant parathyroid tissue in one case. In two patients multivisceral surgery was performed: beside thyroidectomy, neck dissection, tracheal wall resection and resection of the muscular layer of the oesophagus one patient received oesophagectomy and gastric transposition and one patient a lung wedge resection. Both patients had a temporary palliation of tumour-associated symptoms after multivisceral surgery. The first patient died 2 years after oesophagectomy and 12 years after primary diagnosis from local tumour recurrence and cachexia. The second patient is living with tumour recurrence presenting a serum calcium level of 4.2 mmol/l (normal range 2.0 to 2.5 mol/l) and multiple brown tumours 2 years after lung resection and 6 years after the primary diagnosis. CONCLUSIONS: We conclude that parathyroid carcinomas, being difficult to diagnose, warrant radical surgery, including multivisceral resection to prolong survival and reduce tumour and hypercalcaemia associated symptoms.

[Does tissue harmonic imaging allow early determination of postoperative thyroid volume?]. / Erlaubt das Tissue Harmonic Imaging eine frühe postoperative Schilddrüsenvolumetrie?

AIM: Therapy for endemic goitre after surgical resection depends on the residual thyroid volume. Post-operative changes have been known to impair the fundamental sonographic evaluation of residual thyroid tissue. It was our aim to determine whether THI is a feasible method for thyroid volumetry after surgery. METHODS: 48 patients underwent thyroidectomy, hemithyroidectomy, near total resection, or partial resection of the thyroid gland. In all patients THI of the neck was performed 4 (mean; range: 2-7 days) days after surgery using an Elegra sonographic device (Siemens, Erlangen, Germany) with a transmitted frequency of 3.4 MHz and received frequency of 6.8 MHz. The examiner was blinded to the patient's diagnosis and the type of surgery. The residual tissue volume measured by means of THI and intra-operative volumetry were both compared to sonographic volumetry 12 weeks after surgery, the latter serving as the gold standard. Accuracy of THI and intraoperative volumetry were tested for significant differences using a paired t-test. RESULTS: Volumetry by the surgeon was available in 26 patients (54%). The men error of THI volumetry was 2.4 ml (SD: 3.3 ml; maximum: 17 ml). The mean error of intraoperative volumetry was 1.4 ml (SD: 1.9 ml; maximum: 6 ml). The mean difference between THI and intraoperative volumetry was 1 ml (SD: 2.7 ml; maximum: 7 ml; p = 0.085). CONCLUSIONS: THI permits early volumetry of the residual tissue after thyroid surgery comparable with the intraoperative volumetry. Thus, THI may be helpful in guiding the substitution of thyroid hormones.

[Surgical therapy of neuroendocrine tumors of the thymus]. / Chirurgische Therapie neuroendokriner Tumoren des Thymus.

Neuroendocrine tumors of the thymus, also known as thymic carcinoids, are rare tumors of the anterior mediastinum. They occur sporadically or in association with MEN I syndrome. We present five patients (four male, one female; age of first manifestation 19-53 years) who were operated on at our hospital between 1984 and 1995 for neuroendocrine thymic tumors. A hormone-producing tumor presented with Cushing's syndrome in two patients. Two patients had MEN I syndrome. Only in the female patient the primary tumor was confined to the thymus. We found lymph node metastases in three patients and a distant metastasis in one. The neuroendocrine tumors have a high rate of local recurrences and thus we performed 11 operations using a transthoracic or transsternal approach. Since there was no operative mortality and adjuvant therapies are of limited value, we recommend surgery even in case of recurrence.

[Economic restraints shorten the length of hospital stay: thyroid operation as a model case]. / Okonomische Zwänge führen zur Reduktion der stationären VerweildauerBeispiel: Schilddrüsenoperation.

INTRODUCTION: Decreasing the length of stay is a possible means of cost control in the medical system. Therefore we performed a study to test the feasibility of reducing hospital stay to 2 days after thyroid operation. METHODS: In a controlled prospective trial, 238 patients were randomly assigned to group A (2 days of stay) or group B (more than 2 days). Studied were medical standard, practicability, patient acceptance, and quality of life. RESULTS: Of those in group A, 56.6% did not leave the hospital at the scheduled 2nd day post operation. Reasons were preoperative hyperthyroidism ( P<0.011), postoperative hypocalcemia ( P<0.03), or unspecific disturbances. In group B, 28% of the patients left before the established borderline of 3-4 days, and only 35% left on the 2nd postoperative day. CONCLUSION: Reduced length of stay has no negative influence on medical standards. The quality of life of patients leaving the hospital on the 2nd postoperative day was significantly higher. Reducing hospital stay after thyroid operation to 2 postoperative days is desirable and possible without a loss in quality of care, except in case of postoperative complications or unspecific complaints.

The actual role of classic bilateral cervicotomic approach for primary hyperparathyroidism in the era of minimally invasive surgery.

UNLABELLED: Recent advances in preoperative localisation of parathyroid adenomas and intraoperative prove of complete removal of hyperfunctioning parathyroid tissue have fostered less invasive operative procedures which directly target the diseased gland. Such strategies have partially replaced the previous gold standard procedure of bilateral neck exploration. We herein report on our own series of 1099 consecutive operations for primary hyperparathyroidism performed in a 16 year period and provide information and arguments for primary bilateral exploration in selected cases. 97.1% of patients were cured by the primary operation. From 1999 through 2001, 200 patients underwent bilateral neck exploration, whereas 63 unilateral operations were performed (33 patients were treated by minimally invasive video-assisted parathyroidectomy (MIVAP) and 30 by minimally invasive open parathyroidectomy (MIOP). In the remaining 200 patients minimally invasive unilateral parathyroid surgery was not feasible due to concomitant goiter (n = 102), lack of preoperative localisation (n = 30), previous thyroid surgery (n = 10), suspected multiglandular disease (n = 10), or other reasons (n = 8). In 40 patients the decision for bilateral neck exploration was made despite feasibility of a unilateral approach. CONCLUSION: Whereas unilateral exploration produced excellent cure rates in older patients, it is not recommended in patients with a high likelihood of multiglandular disease, presence of a large or multinodular goitre, high PTH levels, giant adenoma, unclear MIBI scans or an unreliable OPTH assay. Contrasting recent reports on a dramatic shift of technique towards minimally invasive procedures unilateral parathyroid surgery may not be preferably advisable in a majority of patients from countries with insufficient iodine supplementation.

Secondary malignancy in patients with sporadic neuroendocrine neoplasia.

The incidence of neuroendocrine neoplasias (NENs), especially of the gastro-entero-pancreatic (GEP), system relatively increased over the past decades, as a result of advanced diagnostic tools, a better clinical awareness, and distinguished pathological diagnostic recognition. Previous reports hypothesized an increased risk for secondary malignancies in patients with NEN especially in GEP-NENs. The present study was designed to investigate the coincidence of NENs and secondary malignancies in a large patient collective. A retrospective analysis was performed on 161 patients (85 female and 76 male) with NEN of various origins. Clinical data of these patients, different classification systems (TNM/WHO), proliferations-based grading, and clinical follow-up were collected and analyzed. Out of 143 patients with a sporadic NEN, 15 (10.49 %) patients were identified with secondary malignant tumors. Median age at the time of the primary operation for NEN was 65 years, whereas the median age of initial diagnosis of associated tumors was 59 years. Mean follow-up time was 61 months. The risk of developing a secondary malignancy was most elevated for patients with an NEN of the lung, the stomach, and the ileum (60, 50 and 20 %, respectively). The spectrum of secondary malignancies included various types of cancer. Kaplan-Meier survival analysis shows a difference suggesting that patients with a secondary malignancy demonstrate a worse survival compared to patients without a secondary tumor; no significance was detected (p = 0.349). Our data suggest that secondary malignancies in patients with NEN's especially in GEP-NENs are found more frequently than in general population. Therefore, patients with NEN need a continuous and detailed follow-up. The reason for the increased incidence of secondary malignancies in patients with NENs remains to be elucidated.

The CB-1 receptor antagonist rimonabant modulates the interaction between adipocytes and pancreatic beta-cells in vitro.

BACKGROUND: Adipocytes produce signalling molecules which can act on target cells including pancreatic beta-cells. In previous studies we found adipocytes to directly stimulate insulin secretion and the proliferation of pancreatic beta-cells in vitro. Rimonabant acts as an antagonist at the cannabinoid-1 (CB-1) receptor which is expressed on adipocytes. Rimonabant decreases insulin levels in vivo. This effect can either be explained by improving insulin sensitivity or by effects on beta-cells including the modulation of adipocyte - beta-cell interactions. OBJECTIVES: To test how pre-treatment of primary human adipocytes with rimonabant affects the cross-talk between adipocytes and pancreatic beta-cells in vitro. RESULTS: Rimonabant had no direct effect on insulin secretion or beta-cell proliferation at a concentration range from 1 nM to 1 µM. This is in line with previous findings showing that in the murine pancreas CB-1 receptors are preferentially expressed on non-beta-cells, while rimonabant is a selective blocker of CB-1 receptors. We found fat-cell conditioned-medium without (FCCM) and after pre-treatment for 24 h with 100 nM rimonabant (FCCM-RB) to induce insulin secretion from primary murine beta-cells to a similar extent. Proliferation of a pancreatic beta-cell line was enhanced by FCCM to 219%, while FCCM-RB inhibited proliferation to 53%. As we previously found Wnt-signalling to mediate effects of adipocytes on beta-cell proliferation we tested the ability of FCCM and FCCM-RB to activate canonical Wnt-signalling in target cells. However, there was no significant difference between the groups: FCCM and FCCM-RB stimulated Wnt reporter gene activity to 181% and 179%, respectively. In addition, there was no significant difference in adiponectin levels between FCCM and FCCM-RB (56.8 vs. 58.1 ng/ml), showing that adiponectin does not mediate the differential effects on beta-cell proliferation by FCCM and FCCM-RB. CONCLUSION: Our data show that rimonabant modulates the adipocyte - beta-cell interaction with respect to beta-cell proliferation and indicate that signalling molecules other than adiponectin and components of the Wnt pathway mediate this cross-talk.