IgG4-related lung disease showing high standardized uptake values on FDG-PET: report of two cases

Update on classification, diagnosis, and management of immunoglobulin G4-related disease

Immunoglobulin G4-related disease (IgG4-RD) is a newly recognized chronic fibro-inflammatory autoimmune disease, and its recognition has been constantly increasing worldwide over the last few years. A correct and timely recognition, as well as appropriate intervention, is crucial for the treatment of IgG4-RD. For certain subtypes of IgG4-RD, organ-specific criteria are formulated to make the diagnosis more accurate. New biomarkers have emerged in the recent years to aid the disease diagnosis, its prognosis prediction, as well as therapy response monitoring. Although recurrence is very common in IgG4-RD, glucocorticoid is still the first-line treatment for the majority of patients. The factors that affect the likelihood of disease relapse are multifaceted. The selection strategy of various steroid-sparing agents is still being explored. Besides, when patients have special sites involvement leading to severe clinical conditions, surgical operation or interventional therapy should also be considered. An update on classification, diagnosis, and management of IgG4-RD is provided in the current study to fully elucidate the recommended clinical practice of this mysterious disease.

IgG4-related disease: a great mimicker of lung cancer

IgG4-related disease is a rheumatological disorder, affecting multiple organ systems, and displaying dense lymphoplasmacytic inflammatory infiltrate and storiform fibrosis on histology. The pulmonary manifestations of IgG4-related disease are varied. Most commonly, bronchovascular consolidation and perilymphatic parenchymal thickening occur. IgG4-related disease can present as a solitary parenchymal mass and is often mistaken for a primary pulmonary or haematological malignancy. This report presents a case of IgG4-related disease in a patient with 6 months reported haemoptysis symptomatology and CT findings of perihilar lymphadenopathy, multiple pulmonary parenchymal nodules and a single parenchymal mass. Clinician cognisance of the histopathological presentation of IgG4-disease is important. It should be considered as a differential in patients for which investigations have ruled out malignancy, as it is responsive to glucocorticoids in the majority of cases.

18F-fluorodeoxyglucose positron emission tomography/computed tomography imaging review of benign lesions of the thorax

2-deoxy-2-(Fluorine-18) fluoro-D-glucose (¹⁸F-FDG) positron emission tomography/computed tomography (PET/CT) has been used exclusively to diagnose malignancies. However, increased ¹⁸F-FDG uptake is not always limited to malignant lesions. This imaging review demonstrates the physiological ¹⁸F-FDG uptake of normal structures in the thorax and illustrates many benign pathological lesions with standardized uptake value >2.5. These various conditions can be broadly categorized into three groups: infective lesions, active granulomatous diseases such as sarcoidosis, noninfectious/inflammatory, or proliferative conditions such as radiation pneumonitis, postlung transplant lymphoproliferative disorders, occupational pleuropulmonary complications, and postsurgical conditions, all of which can demonstrate varying degrees of ¹⁸F-FDG uptake on PET/CT based upon the degree of inflammatory activity. Familiarity of false-positive findings improves the PET/CT evaluation accuracy of benign lesions of the thorax. Radiation exposure and surgical history correlation along with imaging cross check evaluation of radiographs and magnetic resonance images for the anatomic location remains the mainstay of PET/CT characterization of positive findings.

Features of IgG4-related lung disease on 18F-FDG PET/computed tomography imaging

OBJECTIVES

The aim of the study was to summarize the features of immunoglobulin G4-related lung disease (IgG4-RLD) on fluorine 18-fluorodeoxyglucose (F-FDG) PET/computed tomography (CT).

METHODS

In this retrospective case series, 12 consecutive patients (9 men and 3 women, mean age 55.4 ± 13.7 years) with IgG4-RLD were included. The clinicopathological information and features of F-FDG PET/CT imaging were analyzed.

RESULTS

Six (50%) patients had pulmonary involvement alone and six (50%) patients had extrapulmonary involvement with intense F-FDG uptake. Pulmonary manifestations included mass (25%, 3/12), solid nodule (solitary 25%, 3/12; multiple 50%, 6/12), multiple ground-glass opacities (GGOs) (50%, 6/12), thickening of alveolar interstitium (50%, 6/12), and thickening of bronchovascular bundle (33.3%, 4/12). The maximum standardized uptake value (SUVmax) of the solid nodules and masses, multiple GGOs, bronchovascular bundle and the thickening of septa was 4.0 ± 2.5, 2.3 ± 1.8, 1.4 ± 0.6, and 0.9 ± 0.5, respectively. The SUVmax statistically significant linear association with the diameter of masses or solid nodules (P value = 0.03), but no significant inverse linear association (P value = 0.06) with the concentration of serum IgG4 concentration.

CONCLUSIONS

The image patterns of IgG4-RLD on F-FDG PET/CT are varying. Multiple pulmonary manifestations or multiple organ involvement, especially in combination with elevated levels of serum IgG and IgG4, may help to make the diagnosis. A potential major application of PET-CT would be evaluation of response to treatment, and the impact of PET/CT on IgG4-RLD management is worth investigating further in the future.

Photodynamic Diagnosis for Pleural Disseminated Lesions of Lung Cancer Using a Combination of 5-Aminolevulinic Acid and Autofluorescence Observation System

PURPOSE

We developed a diagnostic method for pleural disseminated lesions of lung cancer using a combination of 5-aminolevulinic acid (5ALA) and autofluorescence observation system. We utilized a phenomenon in which externally ingested 5ALA is metabolized to protoporphyrin IX, a precursor of heme, which remains inside malignant cells and emits red fluorescence of approximately 630 nm. The diagnosis was made employing an observation system based on autofluorescence emitted from normal tissues that we have investigated.

METHODS

Between January 2017 and April 2019, we examined 82 lung cancer patients with suspected pleural invasion. We orally administered 5ALA (20 mg/m2) to the patients 4 hours before surgery, and malignant pleural lesions were thoracoscopically visualized using the autofluorescence observation system.

RESULTS

(1) Pleural disseminated lesions were observed in six patients. Of these lesions, two were not detected by usual white light inspection, and the use of this method enabled the diagnosis of disseminated lesions. (2) Regarding the diagnosis of lung cancer pleural invasion to estimate the risk of pleural dissemination, if limited to adenocarcinoma, the sensitivity was 93.9%; specificity, 74.3%; positive predictive value, 60.8%; and negative predictive value, 96.2%.

CONCLUSION

This method may facilitate the detection of minute disseminated lesions that are difficult to detect by usual inspection. In addition, the degree of pleural invasion may be diagnosed to evaluate the need for limited resection such as segmentectomy.

Thoracic Hyper-IgG4-Related Disease Mimicking Malignant Pleural Mesothelioma

We report a rare case of a IgG4-related disease presenting with recurrent pleural effusion, pleural thickness and multiple mediastinal lymphadenopathies and no involvement of other extrathoracic organs. A 65-year-old man with a previous asbestos exposure presented with cough and pain discomfort. A large right pleural effusion was detected and evacuated (siero-haematic liquid). With the suspicious of a pleural mesothelioma, a CT-scan before and a ^18F-FDG PET/CT-scan later were performed revealing multiple pleural thickenings and multiple mediastinal lymphadenopathies with radiotracer uptake. EBUS-TBNA EBUS-TBNA did not result in a formal pathological diagnosis; thus, multiple pleural biopsy were performed via right thoracoscopy. At pathology the pleura was markedly thickened by a chronic fibroinflammatory process with scattered lymphoid follicles and a large number of mature plasma cells. Immunohistochemistry shows a mixed B (CD20+) and T (CD3+) population of lymphocytes, without light chain restriction and an increased number of IgG4-positive plasma cells. A presumptive diagnosis of IgG4-related disease was formulated. Total body CT-scan excluded other organ involvement. Blood test showed elevated serum IgG4 concentrations (253 mg/dL) and mild elevation of acute-phase reactants (C-reactive protein 10.7 mg/L). Autoimmune profile was negative. A diagnosis of definite IgG4-related disease was made, and treatment with prednisone 50 mg/day was started.

IgG4-related respiratory disease

IgG4-related diseases (IgG4-RDs), such as autoimmune pancreatitis and IgG4-related Mikulicz disease, are often accompanied by intrathoracic lesions, which are called IgG4-related respiratory disease (IgG4-RRD). IgG4-RRD has few subjective symptoms, and is usually detected during workup of patients with extra-thoracic lesions of IgG4-RD. IgG4-RRD is characterized by various conditions, including masses, nodules, thickening, and infiltration at numerous sites in the thorax through lymphatic routes. Although elevated serum IgG4 concentrations and pathologic evidence of lymphoplasmacytic infiltrates with abundant IgG4-positive plasma cells are characteristic findings of IgG4-RD, other intrathoracic diseases, such as multicentric Castleman disease and malignancy, may present with similar findings. Developing diagnostic criteria for IgG4-RRD, including clinicoradiological and pathological characteristics, is necessary for its appropriate diagnosis.

IgG4-related disease of pulmonary artery causing pulmonary hypertension

IgG4-related disease (IgG4-RD) is recognized as an immune-mediated condition with pathology features of lymphoplasmacytic infiltrate, storiform fibrosis, and obliterative phlebitis, accompanied with or without elevated serum IgG4 concentrations. However, few of pulmonary artery IgG4-RD causing pulmonary hypertension (PH) was reported.The medical records of 3 patients with pulmonary artery IgG4-RD inducing PH were analyzed retrospectively.Imaging findings demonstrated that the lesions of 3 patients located in pulmonary artery, which were initially diagnosed as pulmonary thrombus or malignant tumor. Computed tomography pulmonary angiography (CTPA), ultrasonic cardiogram, and positron emission tomography/computed tomography (PET/CT) didn't support the diagnosis of pulmonary thrombus or malignant tumor. Right heart catheterization (RHC) showed definite PH. Biopsy by right heart catheterization in 2 patients or pneumonectomy in 1 patient confirmed the diagnosis as IgG4-RD. Treated with glucocorticoids and cyclophosphamide or rituximab, 2 patients' IgG4 concentrations declined sharply and the lesions shrunk gradually. Another patient treated with glucocorticoids died of heart failure.IgG4-RD involved pulmonary artery causing PH was rare. A high index of awareness of this disease is required for early diagnosis and treatment. PET/CT might be a valuable approach to distinguish pulmonary artery IgG4-RD from pulmonary thrombus and malignant tumor.

An initial exploration for comprehensive assessment of IgG4-related lung disease: analyses on the cases enrolled from a systematic review

Background

The existence of two diagnostic systems, the Boston and Japan criteria, for immunoglobulin G4-related disease (IgG4-RD) confuse the medical practice. We aimed to develop a comprehensive assessment based on the weight of each diagnostic item in the existing criteria to improve the diagnostic efficiency of Boston criteria.

Methods

We assessed the patients enrolled by a systematic review of the literatures using the Boston criteria, Japan criteria and a tentative comprehensive assessment respectively, and evaluated the efficiency of each system and their consistency.

Results

Our analysis showed that the distinction in pathological diagnostic items was similar for the Boston criteria (IgG4+/IgG+ ratio, P<0.01; the number of pathological features and IgG4+ count, P<0.001) and comprehensive assessment (IgG4+/IgG+ ratio and the number of pathological features, P<0.001; IgG4+ count, P<0.05). For the Japan criteria, a good distinction in the number of pathological features was demonstrated (P<0.05) but the difference in the IgG4+/IgG+ ratio and IgG4+ count was not significant. There was relatively poor consistency between the Boston and Japan criteria (Kappa =0.482, P<0.001), while there was good agreement (Kappa =0.811, P<0.001), but a significant difference (P=0.011, McNemar matching test), between the Boston criteria and comprehensive assessment.

Conclusions

The current two diagnostic systems have poor consistency. Comprehensive assessment has good agreement with the Boston criteria, but can identify those cases in Boston Category 3 who could still be diagnosed as IgG4-related lung disease. Considering the weight of diagnostic items, the scoring system is a tentative exploration that should be improved with further experience in diagnosing IgG4-related lung disease.

IgG4-related Lung Pseudotumor and Pleural Inflammation with Autoimmune Hepatitis

A 63-year-old man was admitted to our department following a secondary medical examination. Blood tests showed high levels of liver enzymes, IgG, IgG4, and antinuclear antibody. Computed tomography showed tumors in the bilateral lower lobes of the lungs and pleural thickening. After pleural and liver biopsy procedures, he was conclusively diagnosed with IgG4-related lung pseudotumor and pleural inflammation with autoimmune hepatitis. We started treatment with prednisolone 40 mg/day, and chest radiograph and blood tests showed signs of improvement. This was a rare case that suggested an association between IgG4-related disease and autoimmune hepatitis.

Thoracic Paravertebral Mass as an Infrequent Manifestation of IgG4-Related Disease

Case

A 50-year-old African American male presented with abdominal pain and significant weight loss. On physical examination, he had parotid and submandibular gland enlargement associated with right eye proptosis. Computed tomography showed a thoracic paravertebral soft tissue mass, enlarged lymph nodes, and ascending aortic aneurysm. Laboratory results were remarkable for elevated total IgG and IgG4 subclass. The submandibular gland pathology revealed chronic sclerosing sialadenitis, with a large subset of inflammatory cells positively staining for IgG4. The histology of the paravertebral mass demonstrated fibrosclerosis with increased lymphocytic infiltrate, associated with increased IgG4 plasma cells. He was diagnosed with immunoglobulin G4-related disease (IgG4-RD). Steroid therapy initially yielded improvement; however, after steroids were stopped, there was disease recurrence. Prednisone was restarted, and the plan was to start him on rituximab. Interestingly, the patient's brother also had IgG4-RD.

Conclusion

IgG4-RD can present as a paravertebral mass which is usually responsive to steroids; however, recurrent and resistant disease can be seen for which steroid-sparing agents such as rituximab should be considered. In addition, to the best of our knowledge, this is the first reported case of IgG4-RD in two family members presenting as a paravertebral mass, highlighting an exciting area for more research in the future.

Photodynamic diagnosis of visceral pleural invasion of lung cancer with a combination of 5-aminolevulinic acid and autofluorescence observation systems

BACKGROUND

Visceral pleural invasion (PL) is a prognostic factor in lung cancer. In the lung, lymph flows along the pleura, in addition to the flow toward the pulmonary hilum just as the pulmonary arteries and veins run toward it. Even with the same tumor diameter, a PL1 or higher level of pleural invasion is indicative of a more advanced disease stage. Final diagnosis based on the PL level is made by pathological examination of excised specimens. However, if an intraoperative diagnosis can be established, proper selection of the surgical procedure can be made, and unnecessary surgeries for disseminated lesions can be avoided. We investigated optical diagnostic techniques for identifying the presence or absence of visceral pleural invasion in lung cancer by capitalizing on the phenomenon of 5-amino-levulinic acid (5-ALA) being metabolized to a photosensitizing substance or protoporphyrin IX within malignant tumors, generating red luminescence in response to excitation light.

METHOD

This study included 38 patients with primary lung cancer who underwent surgery. They received 5-ALA (20mg/kg) orally 4h before surgery and then we assessed the presence or absence of pleural invasion using an autofluorescence observation system. At visceral pleural invasion sites, we were able to confirm tumor sites visualized in red with a clear border in contrast to the green autofluorescence generated in normal tissues.

RESULT

Red luminescence could be confirmed in 100% of PL1-PL3 patients (14/14) and 41.6% of PL0 patients (10/24) with primary lung cancer. PL0 patients in whom visualization was possible were preoperatively diagnosed as having PL1 and many of them showed vascular channel invasion. The sensitivity, specificity, positive predictive value, and negative predictive value of this diagnostic technique were 100%, 58.0%, 63.1%, and 100%, respectively. Red fluorescence emission was observed significantly more often in pleural invasion cases.

CONCLUSION

Accurate intraoperative diagnosis for visceral pleural invasion in lung cancer may contribute to determining the indications for limited operations such as segmental resection. In addition, accurate local diagnosis has the possibility of being applicable to photodynamic therapy.

Immunoglobulin G4-Related Lung Disease Presenting as Lung Cavitating Mass and Mimicking Lung Cancer

Immunoglobulin G4-related lung disease (IgG4-RLD) is a disease in which abundant activated IgG4-positive plasma cells and lymphocytes infiltrate lung tissues with high 18F-fluorodeoxyglucose uptake. Although various forms of radiologic features of IgG4-RLD have been reported, cavitating mass is a rare imaging feature and should be differentiated from cancer. Therefore, in this article, we report two cases both with unprovoked cough, bloody sputum and presenting quite similar cavitating lesions with high 18F-fluorodeoxyglucose uptake on positron emission tomography/ computed tomography, one of which diagnosed as IgG4-RLD and the other as lung cancer based on biopsy eventually. The awareness of the imaging features of IgG4-RLD and lung cancer described in the present study may help physicians to distinguish one from the other. IgG4-RLD should be considered in the differential diagnosis of cavitary lung lesions.

Resection of pulmonary nodule in a patient with subglottic stenosis under modified spontaneous ventilation anesthesia

Subglottic stenosis is an uncommon structural abnormality that can pose as a difficulty for patients undergoing surgery, and treatment is complex due to the special anatomical location. Pulmonary nodule resection in patients with subglottic stenosis is challenging and has not yet been reported. Here we present a case of pulmonary nodule resection in a patient with subglottic stenosis using uniportal thoracoscopy under spontaneous ventilation anesthesia (SVA). Compared with traditional double lumen endotracheal intubation, we believe this modified technique can significantly reduce airway trauma, and accelerate patient recovery.

Serosal involvement in IgG4-related disease: report of two cases and review of the literature

IgG4-related disease (IgG4-RD) is a recently described entity characterized by lymphoplasmacytic infiltrates, usually mimicking tumors, affecting almost every organ or system. Nevertheless, serosal involvement has been rarely reported. In this article, we report two cases of IgG4-RD with serosal involvement and review the literature. Because of the varied clinical pictures found in our review, we suggest a new terminology for the description of IgG4-RD with serosal involvement.

Coexistence of lung cancer and immunoglobulin G4-related lung disease in a nodule: a case report

BACKGROUND

Immunoglobulin G4-related disease is characterized by infiltration of immunoglobulin G4-positive plasmacytes in various organs. The radiological findings of lung involvement of immunoglobulin G4-related disease include hilar and mediastinal lymphadenopathies, thickness of bronchovascular bundles, peribronchovascular consolidation, and lung nodules. Although a pathological approach is needed to diagnose immunoglobulin G4-related disease, it is ordinarily diagnosed by biopsy from one lesion even if there are multiple lesions. We reported a rare case of the coexistence of immunoglobulin G4-related disease and lung cancer in the same lung nodule.

CASE PRESENTATION

A 72-year-old Japanese man visited our hospital for evaluation of a nodular shadow in the middle lobe of his right lung that was seen on chest radiograph and computed tomography scan. An abdominal computed tomography scan showed a tumefactive lesion in his anterior sacral spine. Blood examinations revealed high serum immunoglobulin G4 concentration at 346 mg/dl, renal dysfunction, and anemia. He underwent right upper lobectomy and regional lymph node dissection. Pathologic findings of the lung nodule showed lepidic pattern adenocarcinoma with infiltration of immunoglobulin G4-positive plasma cells and obliterative phlebitis.

CONCLUSIONS

To date, there have been only few reports on the coexistence of immunoglobulin G4-related disease and lung cancer; here, we report such a rare case. Histologic examination should be considered in cases of suspicious immunoglobulin G4-related disease appearing in a lung nodule.

Extensive Metastatic Cholangiocarcinoma Associated With IgG4-Related Sclerosing Cholangitis Misdiagnosed as Isolated IgG4-Related Sclerosing Cholangitis: A Case Report and Literature Review

As cholangiographic features of IgG4-related sclerosing cholangitis (IgG4-SC) resemble those of cholangiocarcinoma, it is highly confusing between the 2 conditions on the basis of cholangiographic findings. This study presents a case of extensive metastatic cholangiocarcinoma with IgG4-SC misdiagnosed as isolated IgG4-SC, and reviews recent studies of the 2 diseases.A 56-year-old man with no family history of malignant tumors or liver diseases presented with recurrent mild abdominal pain and distention for 3 months. Magnetic resonance cholangiopancreatography showed a 3.7 cm nodular lesion with unclear boundary in segment VI of the liver. Serum IgG4 and CA19-9 were slightly elevated. Histopathological examination was consistent with the consensus statement on the pathology of IgG4-SC. IgG4-SC was thus considered. Due to his mild symptoms, glucocorticoid was not given at first. However, 3 months after his first admission, he had more severe abdominal pain and further elevated serum CA19-9. Actually he was found suffering from extensive metastatic cholangiocarcinoma with IgG4-SC by exploratory laparotomy.The present case serves as a reminder that extensive metastatic cholangiocarcinoma with or without IgG4-SC may be misdiagnosed as an isolated IgG4-SC case if one relies solely on elevated serum and tissue IgG4 levels. We emphasize on the importance of repeated core needle biopsy or exploratory laparoscopy/laparotomy before immunosuppressive drugs are given, and on follow-up of imaging findings and serum CA19-9 once immunosuppressive therapy is started.

Deep-inspiration breath-hold 18F-FDG-PET/CT is useful for assessment of connective tissue disease associated interstitial pneumonia

OBJECTIVE

To examine clinical utility of (18)F-flurodeoxyglucose (FDG)-positron emission tomography (PET)/CT for assessment of interstitial lung disease (ILD) in patients with connective tissue diseases (CTDs).

METHODS

A total of 69 (18)F-FDG PET/CT scans were conducted under deep inspiratory breath hold (DIBH) conditions in 45 CTD patients with ILD, including 16 dermatomyositis/polymyositis, nine systemic scleroderma and seven rheumatoid arthritis. Intensity and distribution of (18)F-FDG signals in PET/CT were determined by standardized uptake value (SUVmax) and visual score in 18 regions, respectively. ILD was defined as active when immunosuppressive therapy was initiated or intensified.

RESULTS

Both SUVmax and visual score were higher in active phase (n = 32) than inactive phase (n = 37) (both p < 0.05), regardless of the underlying CTD and plain CT findings. The both parameters reduced after initiating or intensifying treatment in the follow-up study of 17 active patients except two died patients who showed increased visual score. Another two died patients showed high visual score (15 and 6/18, respectively). Changing ratio of visual score, but not SUVmax was correlated with KL-6 (r(2) = 0.38, p < 0.05) and CRP (r(2) = 0.52, p < 0.05).

CONCLUSION

The DIBH (18)F-FDG PET/CT procedure sensitively illustrates active ILD lesions in CTD and the extended signal distribution is associated with unfavorable clinical outcome.

Clinical review of pulmonary manifestations of IgG4-related disease

IgG4-related disease (IgG4-RD) is a recently recognized systemic disease characterized by tumefactive lesions in various organ systems. The list of organs that can be involved continues to expand, and recently computed tomography (CT) descriptions of the pulmonary lesions found in the disease have been described. The clinical symptoms are nonspecific and may include cough, dyspnea, chest pain, and fever. The appropriate clinical presentation along with elevated serum IgG4 concentrations and pathologic evidence of lymphoplasmacytic infiltrates with abundant IgG4-positive plasma cells and storiform fibrosis is consistent with the disease. Steroids are used to treat this disease in addition to immunosupressives such as cyclosporine or rituxumab for steroid refractory disease. The pulmonary manifestations and imaging features can often mimic malignancy, and as such knowledge of the diagnostic, clinicopathologic, and radiographic features of the disease is required in order to provide appropriate diagnostic workup and treatment.

The changing faces of IgG4-related disease: Clinical manifestations and pathogenesis

Since the earliest reports in 2001, immunoglobulin G4 (IgG4)-related disease has been defined as an autoimmune systemic disease characterized by the lymphoplasmacytic infiltration of affected tissues leading to fibrosis and obliterative phlebitis along with elevated serum IgG4 levels. Prior to this unifying hypothesis, a plethora of clinical manifestations were considered as separate entities despite the similar laboratory profile. The pathology can be observed in virtually all organs and may thus be a challenging diagnosis, especially when the adequate clinical suspicion is not present or when obtaining a tissue biopsy is not feasible. Nonetheless, the most frequently involved organs are the pancreas and exocrine glands but these may be spared. Immunosuppressants lead to a prompt clinical response in virtually all cases and prevent histological sequelae and, as a consequence, an early differential diagnosis from other conditions, particularly infections and cancer, as well as an early treatment should be pursued. We describe herein two cases in which atypical disease manifestations were observed, i.e., one with recurrent neck lymph node enlargement and proptosis, and one with jaundice. Our understanding of the pathogenesis of IgG4-related disease is largely incomplete but data support a significant role for Th2 cytokines with the contribution of innate immunity factors such as Toll-like receptors, macrophages and basophils. Further, macrophages activated by IL4 overexpress B cell activating factors and contribute to chronic inflammation and the development of fibrosis. We cannot rule out the possibility that the largely variable disease phenotypes reflect different pathogenetic mechanisms and the tissue microenvironment may then contribute to the organ involvement.

Photodynamic diagnosis of pleural malignant lesions with a combination of 5-aminolevulinic acid and intrinsic fluorescence observation systems

BACKGROUND

We have developed a new diagnostic method using the photosensitizer 5-aminolevulinic acid (5ALA) for diagnosing intrathoracic malignant lesions. When ingested exogenously, 5ALA is metabolized to a heme precursor, protoporphyrin IX, which stays in malignant cells and emits red to pink luminescence of about 630 nm.

METHODS

We enrolled 40 patients who underwent respiratory surgery and consented to participate in this study. Twenty-eight patients had primary lung cancer, 8 metastatic lung tumors, 2 malignant pleural tumors, and 2 benign tumors. Localization of malignant lesions was attempted by observing such lesions with an autofluorescence imaging system and by comparing the color tone of the autofluorescence between malignant lesions and normal tissues after oral administration of 5ALA. Malignant lesions on the pleural surface emitted pink autofluorescence in contrast to the green autofluorescence of the surrounding normal tissues.

RESULTS

When 28 patients with primary lung cancer were examined according to the degree of pleural infiltration (pl), red fluorescence was confirmed in 10 of 10 patients (100%) with p11-p13 and 5 of 18 patients (27.7%) with p10. The latter 5 patients had been diagnosed with PL1 preoperatively or intraoperatively.

CONCLUSION

This system achieved accurate localization of malignant lesions, suggesting that it may also be applicable to photodynamic therapy.

Photodynamic diagnoses of malignant pleural diseases using the autofluorescence imaging system

BACKGROUND

We conducted a study on photodynamic diagnosis (PDD) using autofluorescence in video-assisted thoracic surgery for minute intrathoracic small dissemination or early malignant pleural mesothelioma.

METHODS

Autofluorescence is the spontaneous emission of light that occurs when mitochondria, lysosomes, and other intracellular organelles absorb light. In normal tissues, green autofluorescence of approximately 520 nm is observed in response to 400-450 nm blue excitation rays. However, in cancer lesions, green autofluorescence is reduced due to thickening of the mucosal epithelium, a decrease in autofluorescent substances, etc., and the color spectrum thus shifts to red-violet. This phenomenon is the basis of PDD.

RESULTS

The color spectrum shift was observed in all tumors located on the pleural surface but not in cases with pleural fibrous disease. Among patients with primary lung cancer, those with pleural infiltration (pl) scores of 1 or greater showed color spectrum shifts due to reduced autofluorescence.

CONCLUSION

Localization of pleural lesions by autofluorescence imaging was found to be useful. In primary lung cancer cases, differentiation between pl0 and pl1 lesions appears to be useful for determining therapeutic strategies including surgical procedures.

Characterizing IgG4-related disease with ¹⁸F-FDG PET/CT: a prospective cohort study

Purpose

IgG4-related disease (IgG4-RD) is an increasingly recognized clinicopathological disorder with immune-mediated inflammatory lesions mimicking malignancies. A cohort study was prospectively designed to investigate the value of ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in characterizing IgG4-RD.

Methods

Thirty-five patients diagnosed with IgG4-RD according to the consensus criteria were enrolled with informed consent. All patients underwent baseline ¹⁸F-FDG PET/CT evaluation. Among them, 29 patients underwent a second ¹⁸F-FDG PET/CT scan after 2 to 4 weeks of steroid-based therapy.

Results

All 35 patients were found with ¹⁸F-FDG-avid hypermetabolic lesion(s); 97.1 % (34/35) of these patients showed multi-organ involvement. Among the 35 patients, 71.4 % (25/35) patients were found with more organ involvement on ¹⁸F-FDG PET/CT than conventional evaluations including physical examination, ultrasonography, and computed tomography (CT). ¹⁸F-FDG PET/CT demonstrated specific image characteristics and pattern of IgG4-RD, including diffusely elevated ¹⁸F-FDG uptake in the pancreas and salivary glands, patchy lesions in the retroperitoneal region and vascular wall, and multi-organ involvement that cannot be interpreted as metastasis. Comprehensive understanding of all involvement aided the biopsy-site selection in seven patients and the recanalization of ureteral obstruction in five patients. After 2 to 4 weeks of steroid-based therapy at 40 mg to 50 mg prednisone per day, 72.4 % (21/29) of the patients showed complete remission, whereas the others exhibited > 81.8 % decrease in ¹⁸F-FDG uptake.

Conclusion

F-FDG PET/CT is a useful tool for assessing organ involvement, monitoring therapeutic response, and guiding interventional treatment of IgG4-RD. The image pattern is suggested to be updated into the consensus diagnostic criteria for IgG4-RD.