Utility of 99mTc-Sulfur Colloid Lymphoscintigraphy and SPECT/CT in Chylothorax and Chylous Ascites

Purpose

To assess the diagnostic efficacy of 99mTc-sulfur colloid lymphoscintigraphy in chylothorax and chylous ascites, and the utility of single-photon emission computed tomography-computed tomography (SPECT/CT) in localizing the sites of leaks.

Methods

Data from patients who underwent lymphoscintigraphy for clinical suspicion of chylothorax or chylous ascites were retrospectively analyzed. Biochemical fluid analysis was taken as the reference standard. Pleural fluid triglyceride level > 110 mg/dL (with pleural fluid/serum ratio > 1) and a cholesterol level < 200 mg/dL (with pleural fluid/serum ratio < 1) were considered confirmatory for chylothorax. Ascitic fluid triglyceride level > 200 mg/dL with a low cholesterol level (ascites fluid/serum ratio < 1) was considered confirmatory for chylous ascites.

Results

26 patients (15 males, 57.7%) aged 9 months to 68 years were enrolled in the study. Based on the reference standard, 17 had chylothorax or chylous ascites (9 with surgical history). Lymphoscintigraphy was positive in 16 (with 1 false positive) and negative in 10 (with 2 false negatives). The sensitivity, specificity, negative predictive value, positive predictive value, and accuracy of lymphoscintigraphy were 88.2% (63.6-98.5%), 88.9% (51.8-99.7%), 80.0% (51.6-93.8%), 93.8% (70.1-99.0%), and 88.5% (69.9-97.6%), respectively. SPECT/CT could localize sites of leaks in 61.5% (8/13) with a localization rate of 77.8% (7/9) and 25.0% (1/4) in patients with surgical and nonsurgical causes, respectively.

Conclusion

99mTc-sulfur colloid lymphoscintigraphy is a highly efficacious noninvasive modality to diagnose chylothorax or chylous ascites with a high positive predictive value. SPECT/CT could localize the sites of leaks more frequently in patients with surgical causes.

Could the chylomicron marker apoB48 be of value in the diagnosis of chylous effusions?

BACKGROUND

Chylous effusions such as chylothorax, chylopericardium and chylous ascites are marked by the abnormal presence of chylomicrons in serous membranes. These relatively rare situations are associated with high morbidity and mortality rates. Given that a macroscopic assessment of the fluid is insufficient, the current gold standard method for chylous effusion is the electrophoretic separation of lipoproteins. Serous effusions are most frequently assayed for triglycerides, with a diagnostic threshold varying between studies. The present study is the first to assess the value of the apolipoprotein B48, specific of the chylomicron, in the diagnosis of chylous effusions.

METHODS

A chemiluminescent sandwich enzyme immunoassay was used to measure levels of apoB48 in remnant samples of effusion fluid sent to our laboratory for chylomicron detection and lipid assays. The diagnostic values of apoB48 and triglyceride assays were compared with that of the gold standard method.

RESULTS

The triglyceride and apoB48 levels and the triglyceride/cholesterol ratio in the effusion fluid were significantly higher in patients with chylous effusion. The threshold values for apoB48 were respectively 2.45, 0.25 and 19.00 µg/mL for a maximal Youden index, a sensitivity > 95 %, and a specificity > 95 %. The apoB48 assay's diagnostic value might be at least as high as that of a triglyceride assay (area under the receiver operating characteristic curve [95 % confidence interval]: 0.84 [0.72, 0.96]) and 0.80 [0.67, 0.94], respectively).

CONCLUSION

ApoB48 appears to be a promising marker for the diagnosis of chylous effusions; the putative diagnostic improvement must be confirmed in larger studies.

Management of lymphoma-associated chylothorax by interventional radiology and chemotherapy: a report of five cases

Chylous effusion is associated with lymphatic obstruction or leakage in mediastinal or abdominal lymph nodes, and is a rare but troublesome complication in patients with malignant lymphomas. Although there is no standard of care, it is often treated with simultaneous chemotherapeutic and non-chemotherapeutic interventions. Here, we describe the cases of five patients with lymphoma-associated chylothorax with the aim of clarifying an effective treatment strategy. All patients achieved a partial response or better for lymphoma. All patients underwent interventional radiology (IVR) procedures, including lymphangiography (LAG) and thoracic duct embolization (TDE). Complete resolution of chylothorax was eventually achieved by IVR procedures or pleurodesis in all patients. No patients experienced serious adverse events related to LAG/TDE. Treatment of chylous effusion required months for most patients (range: 0.2-4.8 months). Our data suggest that a combination of chemotherapy and LAG/TDE is effective for refractory lymphoma-related chylous effusion.

Serous fluid: Reactive conditions

This chapter highlights the steps that would help to analyze any fluid. It highlights importance of knowing gross analysis of fluid along with biochemical information. These parameters along with clinical information are very important in arriving at a differential diagnosis. Morphologic appearances in the fluid can often become challenging and occasionally reactive conditions can reveal changes that may mimic malignancies. This chapter provides not only a framework of approach to assessment of fluid cytology but also shows how to distinguish some of the challenging reactive conditions from the diagnosis of carcinoma. The chapter also utilizes two cases to demonstrate approach to reactive conditions. This review article will be incorporated finally as one of the chapters in CMAS (CytoJournal Monograph/Atlas Series) #2. It is modified slightly from the chapter by the initial authors in the first edition of Cytopathologic Diagnosis of Serous Fluids.

Clinical approach and review of causes of a chylothorax

A chylothorax, also known as chylous pleural effusion, is an uncommon cause of pleural effusion with a wide differential diagnosis characterized by the accumulation of bacteriostatic chyle in the pleural space. The pleural fluid will have either or both triglycerides >110 mg/dL and the presence of chylomicrons. It may be encountered following a surgical intervention, usually in the chest, or underlying disease process. Management of a chylothorax requires a multidisciplinary approach employing medical therapy and possibly surgical intervention for post-operative patients and patients who have failed medical therapy. In this review, we aim to discuss the anatomy, fluid characteristics, etiology, and approach to the diagnosis of a chylothorax.

Transudative chylothorax in a patient with liver cirrhosis: A rare association

Chylothorax is an unusual type of pleural effusion which results from the accumulation of chyle in the pleural cavity. High triglyceride content and presence of chylomicrons in the chyle give this fluid a characteristic milky appearance. Chylothorax most commonly results from the obstruction of the thoracic duct by a malignant lesion or from its traumatic disruption. Liver cirrhosis is an uncommon and frequently underappreciated cause of chylothorax. Pleural effusion in chylothorax is typically described as a lymphocytic predominant, exudative type and it is exceedingly rare to encounter a transudative type of chylothorax. To date, very few cases of transudative chylothoraces have been described in the literature, most commonly in association with liver cirrhosis. Only a limited range of other clinical settings have been linked to transudative chylothorax and timely recognition of these associations can prevent unnecessary, expensive and sometimes invasive workup in this patient population.

Efficacy and safety of low-dose sirolimus for treatment of lymphangioleiomyomatosis

BACKGROUND

Lymphangioleiomyomatosis (LAM) is a rare disease caused by dysregulated activation of the mammalian target of rapamycin (mTOR). Sirolimus, an inhibitor of mTOR, has been reported to decrease the size of angiomyolipomas and stabilize pulmonary function in patients with LAM. However, the optimal dose for the treatment of LAM remains unclear.

METHODS

We conducted a retrospective, observational study of 15 patients with LAM who underwent sirolimus therapy for more than 6 months. The efficacy was evaluated by reviewing the patients' clinical courses, pulmonary function and chest radiologic findings before and after the initiation of sirolimus treatment.

RESULTS

All patients had blood trough levels of sirolimus lower than 5ng/mL. Sirolimus treatment improved the annual rates of change in FVC and FEV1 in the 9 patients who were free from chylous effusion (FVC, -101.0 vs. +190.0mL/y, p=0.046 and FEV1, -115.4 vs. +127.8mL/y, p=0.015). The remaining 7 patients had chylous effusion at the start of sirolimus treatment; the chylothorax resolved completely within 1-5 months of treatment in 6 of these cases. These results resembled those of previous studies in which blood trough levels of sirolimus ranged from 5 to 15ng/mL.

CONCLUSIONS

Low-dose sirolimus (trough level, 5ng/mL or less) performed as well as the higher doses used previously for improving pulmonary function and decreasing chylous effusion in patients with LAM.