Mediastinal metastases of infradiaphragmatic malignancies

Evaluation of 18FDG PET-CT-positive mediastinal-hilar lymph nodes in extrathoracic malignancies by EBUS-TBNA; correlation of SUVmax, and short-axis diameter with the final diagnosis

INTRODUCTION

Intrathoracic lymph node metastasis from extrathoracic neoplasms are rare. Primary malignancies that metastasize to mediastinal-hilar lymph nodes are head and neck , carcinoma breast ,and genitourinary. Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA)/endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) is currently the preferred modality for mediastinal lymph node sampling.

METHODS

Fifty seven patients with extrathoracic malignancies with maximum standardized uptake value (SUVmax) of mediastinal-hilar lymph nodes greater than or equal to 2.5 were taken up for EBUS-TBNA. The histo-cytopathological results obtained from EBUS-TBNA were compared with SUVmax value and short-axis diameter of a lymph node as noted on EBUS.

RESULTS

Out of 74 sampled nodes, 49 (66.2%) were benign and 25 (33.8%) were malignant. The SUVmax range of benign nodes was 2.8-13 as compared to 3-18 of malignant nodes. The size range of malignant and benign nodes were 8-35 mm and 8-30 mm, respectively. The mean size of abnormal nodes (metastatic + granulomatous) was 17.5 (8-35 mm) and the mean SUVmax was 9.1 (3.4-18), and it was a statistically significant difference when compared to reactive (normal) nodes. At SUVmax cut-off 7.5, sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) were 78.5%, 81.2%, 84.6%, and 74.2%, respectively for detecting abnormal nodes. At 13 mm size cut-off, sensitivity, specificity, PPV, NPV were 75.5%, 65%, 75%, and 72%, respectively, for detecting abnormal nodes.

CONCLUSION

The majority of mediastinal-hilar nodes with increased metabolic activity are benign in nature. Size and SUVmax are poor predictors of metastasis in tuberculosis endemic region. There should be a restrictive attitude toward invasive diagnostic testing for mediastinal-hilar nodes in extrathoracic malignancies.

CT-guided iodine-125 brachytherapy as salvage therapy for recurrent mediastinal lymph node metastasis

Background

The treatment of recurrent mediastinal lymph node metastasis (MLNMs) is challenging. We conducted this study to evaluate the effectiveness and safety of computed tomography (CT)‐guided percutaneous iodine‐125 brachytherapy for MLNMs.

Methods

We retrospectively analyzed 33 patients with recurrent MLNMs treated with CT‐guided interstitial implantation of iodine‐125 seeds. Regular contrast‐enhanced CT was conducted to evaluate the tumor response. Follow‐up survival, quality of life, and adverse events were analyzed.

Results

The number of implanted seeds was 16–85 (median, 40). The matched peripheral dose was 110–160 Gy. The patients were followed up for 5–24 months (median, 14 months). At the last follow‐up or death, complete response to therapy was achieved in 11 patients (33.3%) and partial response in 18 patients (54.5%). The median survival time of this cohort was 15.2 months (95% confidence interval [CI], 9.9–20.5 months); the estimated one‐ and two‐year survival rates were 68.6% and 31.1%, respectively. The Karnofsky performance score increased significantly after the procedure (p = 0.007). Pneumothorax with pulmonary compression of 30% to 40% occurred in five (15.2%) patients and was cured after drainage. No severe complications occurred.

Conclusions

CT‐guided iodine‐125 brachytherapy provided a safe and effective choice for recurrent mediastinal lymph node metastasis with significant local therapeutic effects and minor complications, especially for patients who were not eligible for surgical resection and had failed to benefit from systemic therapy.

Lymphatic Pathways of the Thorax: Predictable Patterns of Spread

OBJECTIVE. This article reviews thoracic lymphatic pathways and tributaries, discusses lymphatic anatomic variants and their clinical implications, and emphasizes common patterns of thoracic lymphadenopathy from extrapulmonary malignancies. CONCLUSION. Recognition of common patterns and pathways of thoracic lymphatic drainage can help identify the site of tumor origin and allow a more focused examination of disease extent, both of which are important for disease prognosis and management.

Management of extraretroperitoneal masses in germ cell tumor

PURPOSE OF REVIEW

Management of extraretroperitoneal (ERP) germ cell tumor (GCT) is a complex clinical scenario faced by urologic oncologists. This article reviews the indications and approach to management of ERP GCT masses.

RECENT FINDINGS

ERP GCT management starts with chemotherapy, and for any residual masses, a careful consideration of surgical intervention versus salvage chemotherapy. Decision-making regarding residual ERP masses hinges on tumor markers, and also the anatomical location. These factors should be contextualized by the patient's risk for teratoma or active GCT, which will impact outcome and thus weigh on decision-making conversations with patients who have advanced disease. Technical challenges of surgical management in the postchemotherapy setting also apply in ERP mass resection. The risks of surgical management in the lung and liver, in particular, add special considerations for morbidity. Surgical resection is often the only recourse for a patient who may have chemoresistant disease and may be an important step in achieving cure.

SUMMARY

Surgical management of ERP GCT requires multidisciplinary input, and the urologic oncologist can help guide management with particular emphasis on the indication, timing, and approach to surgical resection.

Lymphatic Drainage from Renal Tumors In Vivo: A Prospective Sentinel Node Study Using SPECT/CT Imaging

PURPOSE

Lymphatic drainage from renal tumors is unpredictable. In vivo drainage studies of primary lymphatic landing sites may reveal the variability and dynamics of lymphatic connections. The purpose of this study was to investigate the lymphatic drainage pattern of renal tumors in vivo with single photon emission/computerized tomography after intratumor radiotracer injection.

MATERIALS AND METHODS

We performed a phase II, prospective, single arm study to investigate the distribution of sentinel nodes from renal tumors on single photon emission/computerized tomography. Patients with cT1-3 (less than 10 cm) cN0M0 renal tumors of any subtype were enrolled in analysis. After intratumor ultrasound guided injection of 0.4 ml ^99mTc-nanocolloid we performed preoperative imaging of sentinel nodes with lymphoscintigraphy and single photon emission/computerized tomography. Sentinel and locoregional nonsentinel nodes were resected with a γ probe combined with a mobile γ camera. The primary study end point was the location of sentinel nodes outside the locoregional retroperitoneal templates on single photon emission/computerized tomography. Using a Simon minimax 2-stage design to detect a 25% extralocoregional retroperitoneal template location of sentinel nodes on imaging at α = 0.05 and 80% power at least 40 patients with sentinel node imaging on single photon emission/computerized tomography were needed.

RESULTS

Of the 68 patients 40 underwent preoperative single photon emission/computerized tomography of sentinel nodes and were included in primary end point analysis. Lymphatic drainage outside the locoregional retroperitoneal templates was observed in 14 patients (35%). Eight patients (20%) had supradiaphragmatic sentinel nodes.

CONCLUSIONS

Sentinel nodes from renal tumors were mainly located in the respective locoregional retroperitoneal templates. Simultaneous sentinel nodes were located outside the suggested lymph node dissection templates, including supradiaphragmatic sentinel nodes in more than a third of the patients.

Experimental computed tomography-guided vena cava puncture in pigs for percutaneous brachytherapy of middle mediastinal lymph node metastases

BACKGROUND

Percutaneous brachytherapy is a valuable method for the treatment of lung cancer and mediastinal lymph nodes metastasis. However, in some of the metastatic lymph nodes in the middle mediastinum, the percutaneous approach cannot be used safely due to possible damage to surrounding anatomical structures. We established an animal model (group of 12 pigs) to assess the safety and feasibility of computed tomography (CT)-guided vena cava puncture.

METHODS

Under CT guidance, an 18G needle was used to puncture the anterior wall of the anterior vena cava (AVC) in 12 pigs. The 18G needle was chosen as it is similar in size to the needles employed for clinical application in brachytherapy. The incidence of complications and vital signs was monitored during the procedure. Thoracotomy was performed to remove AVC specimens, which were analyzed for histological evidence of vessel wall damage and repair.

RESULTS

Following postoperative enhanced CT, two animals were found to have a small pneumothorax (one being hemopneumothorax). The intraoperative oxygen saturation of both animals was not significantly decreased and was maintained at 93-100%. No animals developed mediastinal hematoma. Preoperative, intraoperative, and postoperative changes in blood pressure, heart rate, hemoglobin, and blood oxygen saturation were not significant. Histological evaluation of AVC specimens showed that by 7 days following the procedure, the endothelial layer was smooth with notable scar repair in the muscularis layer.

CONCLUSIONS

CT performed after the procedure and histological preparations confirmed the safety of the procedure. This indicates that percutaneous brachytherapy for metastatic middle mediastinal lymph nodes can be carried out via the superior vena cava.

[Metastatic thoracic lymph node carcinoma from extra-thoracic malignancy or from unknown primary site]

Malignant mediastinal lymph nodes without pulmonary disease may be lymphomatous or the metastases from thoracic or extrathoracic malignancy. More rarely, metastatic lymph nodes are without primary site. Surgery is generally diagnostic, restricted to confirming the metastatic process, because of too numerous and disseminated or unresectable lymph nodes. Radical surgery consisting in lymphadenectomy can be effective in case of mediastinal lymph node malignancy without other extra- and intrathoracic disease. We observed in our experience and in several case reports long-term good results in such cases. We suggest that including surgery in the multimodality treatment of mediastinal metastatic lymph nodes may be advisable in selected patients.

Retrocrural Lymph Node Metastasis Disclosed by (18)F-FDG PET/CT: A Predictor of Supra-diaphragmatic Spread in Ovarian Cancer

PURPOSE

Retrocrural lymph nodes (RCLNs) communicate with retroperitoneal and posterior mediastinal LNs. It is possible that, when RCLNs are involved, supra-diaphragmatic extension will occur in abdomino-pelvic cancers. The authors investigated performance of (18)F-FDG PET/CT to diagnose RCLN metastasis and whether RCLN metastases were associated with supra-diaphragmatic lymphatic metastases of ovarian cancer.

MATERIALS AND METHODS

Sixty-seven patients with stage IV ovarian cancer who had undergone (18)F-FDG PET/CT were included in this retrospective study. Diagnostic performance of (18)F-FDG PET/CT for RCLN metastasis was evaluated. Patients were divided into two groups by presence or absence of supra-diaphragmatic LN metastasis. The prevalences of RCLN metastasis between the two groups were compared and the odds ratio was calculated.

RESULTS

Sensitivity and specificity of (18)F-FDG PET/CT for RCLN metastasis were 96.3 and 100%, respectively. Of the 67 study subjects, 27 patients had RCLN metastases (40.3%). Fifty patients had supra-diaphragmatic LN metastases. (18)F-FDG PET/CT showed 26 RCLN metastases in patients with supra-diaphragmatic LN metastases (54.5%), and only 1 in patients without supra-diaphragmatic LN metastasis (5.9%), and the difference between two groups was statistically significant (P < 0.05). The odds ratio that patients with RCLN metastasis would have supra-diaphragmatic LN metastasis was 17.3 (95% confidence interval = 2.1 to 140.9, P = 0.008).

CONCLUSION

Performance of (18)F-FDG PET/CT to diagnose RCLN metastasis was excellent. RCLN metastasis revealed by (18)F-FDG PET/CT was strongly associated with supra-diaphragmatic LN spread of ovarian cancer. Thus, RCLN metastasis could be used as a predictor of supra-diaphragmatic lymphatic metastasis of ovarian cancer.

Endobronchial ultrasound-guided transbronchial needle biopsy for diagnosis of mediastinal lymphadenopathy in patients with extrathoracic malignancy

Mediastinal lymphadenopathy associated with extrathoracic malignancy or a metastasis of unknown origin (MUO) requires pathological verification. Surgical exploration or endoscopic ultrasound-guided fine needle aspiration is limited to application. We investigated the effectiveness of endobronchial ultrasound-guided transbronchial needle biopsy (EBUS-TBNA) for evaluating mediastinal lymphadenopathy in patients with an extrathoracic malignancy. We retrospectively analyzed data from 59 patients who underwent EBUS-TBNA with a core biopsy because of a suspected mediastinal metastasis between September 2008 and August 2010. All patients had previously been diagnosed with an extrathoracic malignancy (n = 39, 66.1%) or a suspected MUO without a thoracic lesion (n = 20, 33.9%). A total of 88 lymph nodes was analyzed. EBUS-TBNA findings indicated malignancies in 34 patients (57.6%). The EBUS-TBNA sensitivity and specificity for the detection of mediastinal malignancy in patients with a previous extrathoracic malignancy were 96.3% and 100%, respectively. For MUO patients without a thoracic lesion, the sensitivity and specificity were 61.5% and 100%, respectively. The overall sensitivity and specificity were 81.0% and 100%, respectively (P = 0.053). EBUS-TBNA is a safe and effective modality for evaluating mediastinal lymphadenopathy in patients with a previous extrathoracic malignancy or a MUO without a thoracic lesion. The application of this diagnostic tool is likely to have significant clinical implications.

[Isolated malignant mediastinal lymphadenopathy]

Mediastinal adenopathies without pulmonary disease may be benign, lymphomatous or the metastases from intra- or extrathoracic malignancy or more rarely metastases with unknown primary site. We observed 507 patients with isolated mediastinal adenopathies: benign, lymphomatous and metastatic disease represented 41.4% (210/507), 26.8% (136/507), 31.8% (161/507) of them, respectively. Management of the latter was the most challenging. Surgery was generally diagnostic, restricted to confirming the metastatic process, because of too numerous and disseminated or unresectable lymph nodes in 84% of patients (135/161). However, radical surgery consisting in lymphadenectomy proved effective in case of mediastinal lymph node malignancy without other extra- and intrathoracic disease. We observed long-term good results in such cases, which also was demonstrated by case reports in the literature. We suggest that including surgery in the multimodality treatment of mediastinal metastatic lymph nodes may be advisable in selected patients.

Feasibility of sentinel node detection in renal cell carcinoma: a pilot study

PURPOSE

Lymphatic drainage from renal cell carcinoma is unpredictable and the therapeutic benefit and extent of lymph node dissection are controversial. We evaluated the feasibility of intratumoural injection of a radiolabelled tracer to image and sample draining lymph nodes in clinically non-metastatic renal cell carcinoma.

METHODS

Eight patients with cT1-2 cN0 cM0 (<6 cm) renal cell carcinoma prospectively received percutaneous intratumoural injections of (99m)Tc-nanocolloid under ultrasound guidance (0.4 ml, 225 MBq at one to four intratumoural locations depending on tumour size). Lymphoscintigraphy was performed 20 min, 2 h and 4 h after injection. After the delayed images a hybrid SPECT/CT was performed. SPECT was fused with CT to determine the anatomical localization of the sentinel node. Surgery with sampling was performed the following day using a gamma probe and a portable mini gamma camera.

RESULTS

Eight patients, seven with right-sided renal cell carcinoma, were included with a mean age of 55 years (range: 45-77). The mean tumour size was 4 cm (range: 3.5-6 cm). Six patients had sentinel nodes on scintigraphy (two retrocaval, four interaortocaval, including one hilar) with one extraretroperitoneal location along the internal mammary chain. All nodes could be mapped and sampled. In two patients no drainage was visualized. Renal cell carcinomas were of clear cell subtype with no lymph node metastases.

CONCLUSION

Sentinel node identification using preoperative and intraoperative imaging to locate and sample the sentinel node at surgery in renal cell carcinoma is feasible. Sentinel node biopsy may clarify the pattern of lymphatic drainage and extent of lymphatic spread which may have diagnostic and therapeutic implications.

Intrathoracic lymph node metastases from extrathoracic carcinoma: the place for surgery

BACKGROUND

Intrathoracic hilar or mediastinal lymph node metastases (HMLNMs) of extrathoracic carcinomas are infrequent. Their treatment strategy is not established and their prognosis poorly known. We reviewed the place of surgical intervention in their management.

METHODS

Among 565 patients with mediastinal lymph node enlargement, 37 had a history of extrathoracic carcinoma. The enlargement consisted in HMLNMs in 26 (15 men, 11 women), with a mean age of 57.6 (range 19-78) years. Surgical procedures were reviewed.

RESULTS

Diagnostic procedures, comprising mediastinoscopy in 9, anterior mediastinotomy in 2, and video-assisted thoracic surgery (VATS) in 4, were performed mainly because of unresectability due to diffuse and bilateral HMLNMs. Cancer location was breast in 6, kidney or prostate in 2 each, and bladder, rectum, testis, melanoma, and larynx in 1 each. Median survival was 21 months. Resection was performed in 11 patients, comprising posterolateral thoracotomy in 6, muscle sparing thoracotomy in 2, and VATS in 3. Seventeen involved LN stations were removed; of these, primary were kidney in 3, testis or thyroid in 2 each, and larynx, nasopharynx, and intestinum in 1 each. Five-year survival was 41.6% (median, 45 months).

CONCLUSIONS

HMLNMs of extrathoracic carcinoma may be isolated, probably in the context of a particular lymphatic mode of spread. Our experience demonstrates that operation is mainly diagnostic but resection may safely achieve local control of the disease and deserves being advocated in patients with isolated and resectable HMLNMs.

Fixed Size of Enlarged Calcified Lymph Nodes in Esophageal Adenocarcinoma despite Complete Remission

Untreated malignant lymph nodes that are calcified are rare. Publications on such calcifications are restricted to case reports. We present a case of calcified lymph nodes in a patient with adenocarcinoma of the gastroesophageal junction that seemed to be nonresponsive to induction chemotherapy, as they did not decrease in size. However, on pathological examination of the resected lymph nodes no vital tumor cells could be detected anymore. Therefore, we hypothesize that a calcified lymph node is unable to shrink, even after adequate remission on induction chemotherapy. This should be taken into account when clinical decision-making depends on the change in size of an enlarged, calcified lymph node as a measure of treatment effect.

Surgical treatment of metastatic disease to the lung

The presence of distant metastases usually implies disease not amenable to cure through surgical resection. In such cases, chemotherapy is the mainstay of treatment, with surgery or radiation reserved for palliative measures. However, metastases limited to the lung may be resected with resultant prolonged patient survival compared to unresectable, widely disseminated metastases. Isolated pulmonary metastases should therefore not be considered untreatable. In this review, we discuss the pathophysiology of pulmonary metastases. We outline prognostic factors associated with metastases, and propose criteria to help select patients for metastasectomy. Surgical approaches, including various open techniques and video-assisted thoracoscopy, are covered. Surgical issues, including the need for unilateral versus bilateral exploration, the extent of resection to achieve cure, the need for lymph node dissection, and the benefit of repeat operations, are discussed. Finally, we review some of the more common tumors that metastasize to the lungs, and the role of metastasectomy in their treatment. Resection of pulmonary metastases confers a survival benefit to a select group of patients so long as the primary tumor is controlled, metastases are limited to the lungs, the patient can tolerate the operation from a cardiopulmonary standpoint, and the metastases are completely resected.

Ultrastructure and Estrogen Regulation of the Lymphatic Stomata of Ovarian Bursa in Mice

The ovarian bursa is a key player in maintaining adaptive ovarian microenvironment for ovulation. The lymphatic stomata are believed to be a major contributor to execute the function of the ovarian bursa, whereas little is known about their ultrastructure and regulation. Here, we examined the ultrastructure of lymphatic stomata in mouse ovarian bursa by scanning electron microscopy and transmission electron microscopy and investigated its regulation by estrogen. We found that the mesothelium on the visceral layer of mouse ovarian bursa was composed of the cuboidal and flattened cells. The lymphatic stomata with round and oval shapes were mainly among the cuboidal cells. The particles, cells, and fluid passed through the stomata and entered into the lymphatic drainage unit composed of connective tissue and lymphatic endothelial cells beneath the stomata. We also used trypan blue as a tracer and found that the absorption of trypan blue through the lymphatic stomata was increased by estrogen that enlarged the average opening area of lymphatic stomata. Furthermore, we detected that there existed estrogen receptors in the nuclei of the mesothelial cells on the visceral ovarian bursa by using immunoelectron microscopy. Taken together, these data suggest that both the absorption and opening area of the lymphatic stomata in mouse ovarian bursa may be influenced by estrogen.

CT of thoracic lymph nodes. Part II: diseases and pitfalls

CT is the primary non-invasive technique for the diagnostic evaluation of thoracic lymph nodes. The CT patterns and anatomic location of thoracic lymph node involvement can provide important clues in the diagnosis of many diseases. Part I of the pictorial review illustrates the anatomic location and drainage of thoracic lymph nodes in the chest wall, mediastinum, and lungs through examples of pathologic involvement. Part II of the pictorial review focuses on CT patterns of lymph node involvement in various pulmonary and extrapulmonary diseases, differential diagnoses based on CT findings, and pitfalls.

Features of the peritoneal covering of the lesser pelvis with special reference to stomata regions

Occasional reports describe various aspects of the fine morphology of the pelvic peritoneum, but its complete organ characteristics remain undefined. The peritoneal covering of the urinary bladder, rectum, uterus, uterine tube, ovary, broad ligament (BL) and testis in Wistar rats was examined by means of transmission and scanning electron microscopy (TEM, SEM). Unusually complicated relief and stomata between the cubic mesothelial cells characterized the surface of the BL. Deep, parallel furrows separated the wide longitudinal folds over the entire length of the uterine tube. The uterus and the ovary formed less numerous, shallow or extremely deep crypt-like invaginations, as well as serous villus-like or papilla-like evaginations. The flat cells were the predominant cell type over the BL, while the cubic mesothelium was the basic covering of the organs. Most of the cubic cells were located in the invagination of the submesothelial layer (SML). Such cells formed an almost smooth surface over the urinary bladder or formed larger areas of the rectum and the testis surfaces. Numerous microvilli, ciliae, round evaginations and complex lamellar bodies characterized their apical plasmalemma. In conclusion, the mesothelial heterogeneity is a stable feature of the lesser pelvis peritoneum, confirmed by TEM and SEM. The cubic mesothelium characterizes the organ peritoneum, while the BL plays the role of the parietal sheet, involving lymphatic units in the SML. The different types of contacts between the mesothelio-endothelial cells, large lymphatic vessels and occasional stomata are the usual components of the lymphatic units in norm, visible by TEM. Images of stomata, seen by SEM, demonstrate oval-shaped deep channel-like gaps surrounded by cubic mesothelium. The last data extend the evidence on stomata regions, which resemble the diaphragmatic ones. Clusters of cells (macrophages, mastocytes and Lymphocytes), small vessels (blood or lymphatic) and nerve fibers (unmyelinated and rare myelinated) form highly specialized complexes in the SML of the ovary, the uterus and the testis.

Transendothelial transport and migration in vessels of the apparatus lymphaticus periphericus absorbens (ALPA)

The vessel of the apparatus lymphaticus periphericus absorbens (ALPA) represents the sector with high absorption capacity of the canalization of the lymphatic vascular system. It plays a basic role in preserving tissue homeostasis and in directing interstitial capillary filtrate back to the bloodstream. ALPA lymphatic endothelium differs from the endothelia of conduction and flowing vessels (precollectors, prelymph nodal and postlymph nodal collectors, main trunks), since it presents a discontinuous basement membrane, which is often absent, and lacks pores and fenestrations. The mesenchymal origin of the ALPA lymphatic vessel, morphological and ultrastructural aspects, intrinsic contractile properties, the presence of valves, innervation, and specific lymphatic markers that reliably distinguish it from blood capillaries are studied. Furthermore, its role in lymph formation through different mechanisms (hydrostatic pressure and colloidal osmotic-reticular mechanisms, vesicular pathway, and intraendothelial channel) is investigated. We have studied morphological and biomolecular mechanisms that control the transendothelial migration, from the extracellular interstitial matrix into the lumen of the lymphatic vessel, of cells involved in immune response and resistance (lymphocyte recirculation, etc.) and in the tumoral metastatic process via the lymphatic system. Finally, future research prospects, clinical implications, and therapeutic strategies are considered.

Endoscopic ultrasound-guided fine-needle aspiration in patients with mediastinal abnormalities and previous extrathoracic malignancy

Enlarged mediastinal lymph nodes in patients with previous extrathoracic malignancy require pathological verification. However, surgical procedures lead to morbidity and (rarely) mortality. Endoscopic ultrasound with fine-needle aspiration (EUS-FNA) is a minimally invasive, outpatient procedure. We prospectively assessed its usefulness in patients with mediastinal abnormalities and previous extrathoracic malignancy. All patients underwent EUS-FNA prior to planned surgical procedures. Specimens were categorised as positive, negative, or inconclusive. Surgical procedures were cancelled after positive EUS-FNA. Twenty patients underwent EUS-FNA, being positive in eleven and providing an alternative diagnosis in one patient (a total of 60%). In 8 patients, EUS-FNA was negative or inconclusive, while surgery was positive in five and negative in three. Sensitivity and specificity of EUS-FNA were 69 and 100%, respectively. EUS-FNA is useful in the assessment of mediastinal abnormalities in patients with previous extrathoracic malignancy. Surgical diagnostic procedures were precluded in 60% of such patients.

Metastatic thoracic lymph node carcinoma with unknown primary site

BACKGROUND

Metastatic cancer in thoracic lymph nodes without a primary site is rare. The purpose of this study is to draw attention to this probably underestimated entity, to speculate on its possible origins, and to suggest guidelines for its treatment.

METHODS

Eight heavy smokers with no past medical history of cancer were diagnosed at operation to have malignant cells in intrathoracic lymph nodes (N1 or N2) with no primary site in the lung. All patients underwent an exploratory thoracotomy with a presumed diagnosis of lung cancer except one who presented with a middle lobe mucosa-associated lymphoid tissue lymphoma. We reviewed the type of surgical resection, histologic and immunohistochemical analysis of resected specimens, treatments, survival, and long-term results.

RESULTS

Resections performed were pneumonectomy (n = 4), lobectomy (n = 3), and bilobectomy (n = 1). All patients underwent complete mediastinal lymph node dissection. Lung resection was performed for mucosa-associated lymphoid tissue lymphoma (n = 1) and for tumorlike lesions that appeared to be tuberculoma (n = 1) and intrapulmonary metastatic lymph nodes (n = 6). Malignant cells were located in intrapulmonary lymph nodes alone (n = 3) or also in mediastinal lymph nodes in three other cases. All these tumors were cytokeratin-positive, demonstrating their epithelial nature. Pulmonary origin was confirmed in two cases (thyroid transcription factor 1-positive and thyroglobulin-negative). No other origin could be demonstrated by immunochemistry. Three patients died within the first year. All other patients are still alive without recurrence (Kaplan-Meier 5-year survival rate, 62.5%).

CONCLUSIONS

Frequency of metastatic cancer in thoracic lymph nodes without a primary site is probably underestimated because the cancer is routinely diagnosed by mediastinoscopy and considered as metastatic disease not amenable to operation. The origin of the disease, either pulmonary, endogenous, or from extrathoracic sites, is often difficult to assess. Nevertheless, our data confirm those of the literature and demonstrate that survival can be increased by operation. This implies diagnosis of the entity and consideration that thoracic lymph node involvement can apparently be isolated and therefore resectable.

Postinflammatory changes of the diaphragmatic stomata

Numerous investigations concerning the fine morphology of diaphragmatic stomata have been performed, but its ultrastructural changes in experimental conditions remain unclear. The present study demonstrates the peritoneal side of the diaphragm in adult Wistar rats by transmission electron microscopy. Ten experimental animals were observed 5 and 8 days after Pseudomonas aeuriginosa instillation (PI) into the peritoneal cavity. A control group of 6 rats showed flat mesothelial covering on basal lamina (BL) and connective tissue layer, as well as cubic mesothelial cells, single stomata over underlying lymphatic lacunae (LL). Five days after PI the mesothelial cells had more numerous microvilli, microvesicles, vacuoles, lysosomes and a lesser number of specialized contacts. The multiplication of the extravasal cells and larger intercellular spaces lead to thickenings of the connective tissue around LL. LL were larger and located in close proximity of the mesothelium. Intercellular spaces in the mesothelial layer and different types of contacts between mesothelial cells and endothelial protrusions of LL (with common BL or without BL) were encountered. Eight days after PI the mesothelium, endothelium of LL, their BL and surrounding connective tissue were interrupted and structurally modified to form typical new channels--stomata. The larger portion of the channels were formed of mesothelial cells, while the endothelial cells participated in the submesothelial part. LL were more numerous than in the previous period, and were arranged in groups. LL increased their vertical (50.59 microm) and horizontal (155.57 microm) diameter, as compared with control animals (respectively 12.37 microm and 74.08 microm). Neighbouring LL were separated by thin or thick septae. Peristomatal mesothelial cells or more rarely endothelium formed valve- or bridge-like structures. Valves on the opposite side of LL were observed. Groups of electron-dense bodies characterized some tall endothelial cells of LL. Cubic mesothelium, endothelium of the LL, both BL, the cell connections that formed new stomata, LL and surrounding connective tissue underwent rapid and parallel changes after PI. Among these elements of the lymphatic regions mentioned above, the mesothelium and endothelium of LL had a main role in experimental conditions.

A scanning electron microscopy study of peritoneal stomata in different peritoneal regions

Peritoneal stomata constitute the principal pathways for the drainage of intraperitoneal contents from the peritoneal cavity to the lymphatic system and have been claimed to be exclusively restricted to the peritoneal surface of the diaphragm. This concept has been revised by the demonstration of peritoneal stomata in the omental, mesenteric, ovaric and pelvic peritoneum. Therefore, the aim of this study was to further assess peritoneal surfaces of several other abdominal organs and of the abdominal wall with special reference to the occurrence of peritoneal stomata. The peritoneum covering the spleen, stomach, intestine, liver, diaphragm and anterior abdominal wall obtained from rats was examined by scanning electron microscopy. Whereas the splenic and hepatic peritoneal surfaces were composed of uniformly distributed cuboidal mesothelial cells, the gastric and intestinal peritoneal surfaces were arranged in parallel folds composed of prominent mesothelial cells with elongated finger-like cytoplasmic processes. In addition to diaphragmatic peritoneal stomata, mesothelial openings were also found on the peritoneal surfaces covering the anterior abdominal wall and the liver. The parietal peritoneal stomata were arranged in clusters, oval in shape and delimited by flattened mesothelial cells exposing the underlying submesothelial connective tissue. The hepatic mesothelial openings formed by deep channel-like gaps of adjacent cuboidal mesothelial cells were almost completely occluded by a dense microvillous coat. As the submesothelial connective tissue was not identifiable with certainty, the mesothelial openings were regarded as corresponding to stoma-like structures. These findings yield further evidence that peritoneal stomata are obviously not confined to the diaphragmatic area but extend to other peritoneal regions. It is therefore suggested that these extra-diaphragmatic parietal and visceral peritoneal surfaces contribute to the absorption capacity of the entire peritoneum and are subsequently involved in either therapeutic procedures or pathological processes affecting the peritoneal cavity.

A study of the three-dimensional organization of the human diaphragmatic lymphatic lacunae and lymphatic drainage units

The peritoneal stomata, lymphatic drainage units and subperitoneal terminal lymphatics, called lymphatic lacunae, form a specialized drainage system in the diaphragm, by which absorption of fluid in bulk, particles and cells is carried out in the peritoneal cavity. The aim of this study is to elucidate the three-dimensional organization and function of the subperitoneal lymphatic lacunae and lymphatic drainage units by using lymphatic casts in the scanning electron microscope (SEM), ODO (OsO4-DMSO-OsO4) freeze fracture, conventional SEM and the transmission electron microscope (TEM). The subperitoneal lymphatic lacuna is unique for its large size and its multiple morphology and can be recognized by its broad, flattened enlargement and the blind-ends of lymphatic vessels, from which extend numerous main lymphatic vessels and side branches. These lymphatic vessels communicate with each other and form a rich lymphatic plexus under the diaphragmatic peritoneum. Two layers of lymphatic networks, i.e. the subperitoneal plexus and the deeper plexus are found in the muscular portion. Only one layer is present in the tendinous portion of the human diaphragm. The lymphatic plexus is denser in the tendinous portion than that in the muscular portion. The lymphatic lacunae occur exclusively in the muscular portion of the human diaphragm. The lumina of lymphatic lacunae are separated from the peritoneal cavity by a barrier consisting of cuboidal mesothelial cells, endothelial cells of the lymphatic lacunae and intervening connective tissue forming a lymphatic drainage unit. All these three components of the lymphatic drainage unit abut upon each other, but are not linked by specialized junctions. The cuboidal mesothelial cells frequently extend valve-like cytoplasmic processes that bridge the subperitoneal channel and make give it a tortuous course. The fibrous layer of the connective tissue is arranged in fiber bundles and gives a three-dimensional network forming the floor of the peritoneal stomata and the roof of the lymphatic lacunae. Via the fibrous network, the cuboidal mesothelial cells and the endothelial cells of the lacunae come into close contact with each other and form short subperitoneal channels which connect the peritoneal cavity with the subperitoneal lymphatic lacunae. The lymphatic drainage units may regulate the material absorption of the peritoneal stomata from the peritoneal cavity. It is suggested that the peritoneal stomata together with the subperitoneal channels, lymphatic drainage units and lymphatic lacunae comprise an important diaphragmatic lymphatic drainage system which plays an important role in the absorption of materials from the peritoneal cavity.