A Potential Role for F-18 FDG PET/CT in Evaluation and Management of Fibrosing Mediastinitis

Pulmonary Hypertension Caused by Fibrosing Mediastinitis

Pulmonary hypertension (PH) is a progressive and severe disorder in pulmonary hemodynamics. PH can be fatal if not well managed. Fibrosing mediastinitis (FM) is a rare and benign fibroproliferative disease in the mediastinum, which may lead to pulmonary vessel compression and PH. PH caused by FM (PH-FM) is a pathologic condition belonging to group 5 in the World Health Organization PH classification. PH-FM has a poor prognosis because of a lack of effective therapeutic modalities and inappropriate diagnosis. With the development of percutaneous pulmonary vascular interventional therapy, the prognosis of PH-FM has been greatly improved in recent years. This article provides a comprehensive review on the epidemiology, pathophysiologic characteristics, clinical manifestations, diagnostic approaches, and treatment modalities of PH-FM based on data from published reports and our medical center with the goal of facilitating the diagnosis and treatment of this fatal disease.

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PH-FM, as a type of rare condition in group 5 PH, has a poor prognosis because of a lack of effective therapeutic modalities and frequent misdiagnosis and underdiagnosis.

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The most prevalent trigger of FM is H-FM in the United States and TB-FM in China.

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Imaging findings, including mismatched perfusion defects in the V/Q scan, FM dyad, and FM triad are important diagnostic clues, and clinical classification facilitates decision making in diagnosis and therapeutics.

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Because of the limited efficacy of drug therapy as well as the uncertain effectiveness and high risk of surgical treatment, endovascular interventional modality is currently the preferred therapeutic option, although procedure-related complications and intrastent restenosis after PV intervention need to be addressed.

Spectrum of [18F]FDG-PET/CT Findings in Benign Lymph Node Pathology

Diffuse lymphadenopathy has a long differential diagnosis that includes both malignant and benign causes. As part of the lymphadenopathy work-up, many patients undergo [¹⁸F]FDG-PET/CT for purposes of ruling out malignancy. FDG-avid lymph nodes, however, are not specific for malignancy. This review will illustrate the spectrum of nodal findings on FDG-PET/CT with correlation to other cross-sectional imaging and clinical history in patients with representative infectious, inflammatory, and benign lymphoproliferative disorders. These findings are important for the nuclear medicine radiologist to understand, as they can represent common pitfalls in the work-up of lymphadenopathy. While FDG-PET/CT may be limited in ascertaining a definitive diagnosis in a disease process as the cause of lymphadenopathy, it can help to narrow this differential and rule out certain diseases in the correct clinical context.

The impact of infection and inflammation in oncologic 18F-FDG PET/CT imaging

Sites of infection and inflammation can be misleading in oncology PET/CT imaging because these areas commonly show ¹⁸F-FDG activity. Caution in the interpretation must be taken to avoid the misdiagnosis of malignancy. Utilization of both CT findings as well as patient history can help differentiate benign infectious and inflammatory processes from malignancy, although occasionally additional work-up may be required. This article discusses the mechanism of ¹⁸F-FDG uptake in infection and inflammation with illustrative examples.

Multimodality Imaging of Focal and Diffuse Fibrosing Mediastinitis

Fibrosing mediastinitis is a rare benign but potentially life-threatening process that occurs because of proliferation of fibrotic tissue in the mediastinum. The focal subtype is more common and typically is associated with an abnormal immunologic response to Histoplasma capsulatum infection. Affected patients are typically young at presentation, but a wide age range has been reported, without a predilection for either sex. The diffuse form may be idiopathic or associated with autoimmunity, usually affects middle-aged and/or elderly patients, and is more common in men. For both subtypes, patients present with signs and symptoms related to obstruction or compression of vital mediastinal structures. The most common presenting signs and symptoms are cough, dyspnea, recurrent pneumonia, hemoptysis, and pleuritic chest pain. Patients with the diffuse subtype may have additional extrathoracic symptoms depending on the other organ systems involved. Because symptom severity is variable, treatment should be individualized with therapies tailored to alleviate compression of the affected mediastinal structures. Characteristic imaging features of fibrosing mediastinitis include infiltrative mediastinal soft tissue (with or without calcification) with compression or obstruction of mediastinal vascular structures and/or the aerodigestive tract. When identified in the appropriate clinical setting, these characteristic features allow the radiologist to suggest the diagnosis of fibrosing mediastinitis. Careful assessment is crucial at initial and follow-up imaging for exclusion of underlying malignancy, assessment of disease progression, identification of complications, and evaluation of treatment response. Online supplemental material is available for this article. ^©RSNA, 2019.

Aggressive and progressive fibrosing mediastinitis involving the thoracic spine mimicking malignancy: A case report

Fibrosing mediastinitis is an uncommon benign disorder in which a chronic inflammatory reaction results in diffuse fibrosis of the mediastinum, potentially compromising the airways, great vessels and other mediastinal structures. Herein we describe a progressive course of fibrosing mediastinitis in a 72-year-old man. Computed tomography images depicted a diffuse, infiltrative, soft tissue mass involving the esophagus and superior vena cava in the mediastinum. Magnetic resonance imaging revealed destruction of the adjacent thoracic spine. Positron emission tomography-computed tomography also revealed increased metabolism in the periphery of the mass.

Post-tuberculous fibrosing mediastinitis: a review of the literature

Fibrosing mediastinitis (FM) is a rare disease where there is thickening of the fibrous tissue in the mediastinum. While histoplasmosis is the the most common recognised cause, the link with tuberculosis (TB) has been rarely documented. We review the link between TB and FM, and describe a case of probable TB-related FM.Our case is of a 74-year-old man who presented with breathlessness 3 years after fully treated TB. Scans revealed a calcified soft tissue mass within the mediastinum, and a diagnosis of fibrosing mediastinitis resulting in pulmonary hypertension was made. Tests for histoplasmosis and IgG4 staining were negative. Surgical intervention was not felt to be beneficial, and he was treated with prednisolone and mycophenolate mofetil.In the review, we highlight the two forms of mediastinitis—granulomatous versus fibrous, and how these two entities may be on a spectrum of disease progression. We also explore the prevalence, clinical presentation, pathogenesis, imaging techniques and treatment options of TB-related FM.

Sclerosing Mediastinitis Presenting as Complete Heart Block

Sclerosing Mediastinitis (SM) is a rare condition which is characterized by the presence of dense fibrosis which infiltrates and encroaches upon various structures in the mediastinal cavity. Depending on the extent and the predominant organ of involvement, the patient presents with symptomatology of dysphagia, superior vena cava compression syndrome or dyspnoea. However, the involvement of the heart is rarely seen. Aetiologies of SM are several, with infections being the most common. We discuss a case of SM involving the oesophagus, descending aorta, hilum of lungs and the heart secondary to mucormycosis in an immunocompetent male.

Fibrosing mediastinitis: when to suspect and how to evaluate?

Fibrosing mediastinitis (FM), which is also known as mediastinal fibrosis or sclerosing mediastinitis, is an uncommon, benign and progressive condition characterized by an invasive proliferation of fibrous tissue within the mediastinum. Tuberculosis and histoplasmosis are the major causes of the granulomatous variety, while non-granulomatous FM is an idiopathic reaction to autoimmune syndromes, drugs and radiation. Contrast-enhanced CT is the investigation of choice that can diagnose, and assess the extent and the severity of involvement. We are presenting a case of FM in a young female who presented with complaints of breathlessness, occasional cough and diffuse chest pain for 3 months.

The role of PET scan in monitoring the progression of fibrosing mediastinitis

We present the case of a 31-year-old man who presented with acute chest pain. Computed tomography scan showed a mediastinal mass engulfing right main-stem bronchus and another mass surrounding descending aorta. Positron emission tomography (PET) scan showed high mass metabolic activity. Histopathological evaluation revealed fibroinflammatory scarring. He was diagnosed with idiopathic fibrosing mediastinitis, started on prednisone and tamoxifen treatment, and monitored with serial PET scans. Nine months after treatment initiation, paraaortic abnormality had resolved and mediastinal mass had regressed.

Fibrosing mediastinitis: an unusual cause of pulmonary symptoms

Fibrosing mediastinitis (FM), also known as granulomatous or sclerosing mediastinitis, is an uncommon but serious cause of chest symptoms. Due to an infectious or inflammatory challenge, production of collagen occurs in the confined space of the mediastinum. Collagen formation leads to compression of vital structures, resulting in cough, chest pain and dyspnea. The majority of cases of FM occur as a result of prior exposure to Histoplasma capsulatum. The following is a case of a previously healthy young woman who presented with a 3-month history of cough, chest pain and trouble breathing, and was subsequently found to have fibrosing mediastinitis. Fibrosing mediastinitis should be considered in the differential diagnosis of cough, chest pain and dyspnea, primarily when findings such as increased venous pressure are present on physical exam and hilar abnormalities are seen on chest radiograph. Clinical presentation, diagnosis and management of fibrosing mediastinitis are discussed.

Fibrosing mediastinitis: clinical presentation, therapeutic outcomes, and adaptive immune response

Fibrosing mediastinitis (FM) is a rare disorder characterized by the invasive proliferation of fibrous tissue within the mediastinum. FM frequently results in the compression of vital mediastinal structures and has been associated with substantial morbidity and mortality. Its pathogenesis remains unknown. However, in North America most cases are thought to represent an immune-mediated hypersensitivity response to Histoplasma capsulatum infection. To characterize the clinical disease spectrum, natural disease progression, responses to therapy, and overall survival, we retrospectively analyzed all 80 consecutive patients with a diagnosis of FM evaluated at Mayo Clinic, Rochester, MN, from 1998 to 2007. Furthermore, we characterized the adaptive immune response in 15 representative patients by immunohistochemistry. The majority of patients presented with nonspecific respiratory symptoms due to the compression of mediastinal broncho-vascular structures. Chest radiographic imaging most frequently revealed localized, invasive, and frequently calcified right-sided mediastinal masses. Most patients had radiographic or serologic evidence of previous histoplasmosis. In contrast to earlier reports summarizing previously reported FM cases, the clinical course of our patients appeared to be more benign and less progressive. The overall survival was similar to that of age-matched controls. There were only 5 deaths, 2 of which were attributed to FM. These differences may reflect publication bias associated with the preferential reporting of more severely affected FM patients in the medical literature, as well as the more inclusive case definition used in our consecutive case series. Surgical and nonsurgical interventions effectively relieved symptoms caused by the compression of mediastinal vascular structures in these carefully selected patients. In contrast, antifungal and antiinflammatory agents appeared ineffective. Histologic examination and immunostaining revealed mixed inflammatory infiltrates consistent with a fibroinflammatory tissue response in these histoplasmosis-associated FM cases. The immune cell infiltrates included large numbers of CD20-positive B lymphocytes. As B lymphocytes may contribute to the pathogenesis of the disease, therapeutic B-cell depletion should be investigated as a therapeutic strategy for FM.