Systemic disseminated tuberculosis mimicking malignancy on F-18 FDG PET-CT. Clin Nucl Med. 2008;33:49-51. [PMID: 18097261 DOI: 10.1097/rlu.0b013e31815c5004]

FDG PET/CT for Staging and Restaging Malignant Mesothelioma

Malignant mesothelioma is an aggressive tumor originating from the mesothelial cells and presenting in general with a very poor prognosis. The pleural localization represents the prevailing disease site, while peritoneal involvement is commonly rare. The WHO classifies mesotheliomas into epithelioid, biphasic, and sarcomatoid histotypes, having diverse outcome with the sarcomatoid or biphasic forms showing the poorest prognosis. Given the peculiar rind-like pattern of growth, mesothelioma assessment is rather challenging for medical imagers. Conventional imaging is principally based on contrast-enhanced CT, while the role of functional and metabolic imaging is regarded as complementary. By focusing essentially on the staging and restaging role of [18F]FDG PET/CT in malignant mesotheliomas, the present review will summarize the available data present in literature and provide some hints on alternative imaging and future perspectives. Given the prevailing incidence of pleural disease, the majority of the information will be addressed on malignant pleural mesothelioma, although a summary of principal characteristics and imaging findings in patients with peritoneal mesothelioma will be also provided.

Disseminated tuberculosis mimicking abdominal metastatic carcinoma: A case report

RATIONALE

Extra-pulmonary tuberculosis (TB) has long been a diagnostic challenge for clinicians, often requiring extensive workup and invasive procedures, with the risk of significant complications. Endoscopic ultrasound-guided fine-needle aspiration (EUS-FNA) is a minimally invasive and highly accurate diagnostic modality for the evaluation of mediastinal and abdominal lymphadenopathy and masses. Several reports on the utility of EUS-FNA as a favorable method for diagnosing extrapulmonary TB have been published.

PATIENT CONCERNS

A 54-year-old man complained of intermittent melena.

DIAGNOSES

18 fluorine-fluorodeoxyglucose positron emission tomography/computed tomography revealed suspected carcinoma metastasis. EUS-FNA did not reveal any evidence of malignancy.

INTERVENTIONS AND OUTCOMES

Laparoscopy was performed, and frozen section pathology during surgery showed granulomas with focal necrosis. Mycobacterium tuberculosis polymerase chain reaction was positive, but acid-fast bacilli staining was negative. Anti-TB treatment was initiated, and the patient was advised to visit the local TB dispensary regularly.

LESSONS

The presence of atypical inflammation of inadequate material or non-representative samples of extra-pulmonary TB was observed on EUS-FNA cytology. Mycobacterium tuberculosis polymerase chain reaction and acid fast bacilli should be performed to diagnose TB because of its higher sensitivity.

Case Report: Metagenomic Next-Generation Sequencing in Diagnosis of Disseminated Tuberculosis of an Immunocompetent Patient

Disseminated tuberculosis (TB) is a rare disease and mainly occurs in immunodeficient patients. It is marked by hematogenous or lymphatic dissemination of Mycobacterium tuberculosis, causing tuberculous infection involving any organ system. Here, we report a case of disseminated TB involving lung, liver, spine, mediastinum, and prostate in an immunocompetent man. The present patient found a hepatic mass without any symptom during health examination. In the next 2 years, further examinations revealed multiple lesions in the lung, mediastinum, spine, and prostate. Imaging examinations, such as contrast-enhanced abdominal CT, F-18 FDG-PET/CT, and radionuclide bone scan, suggested the diagnosis of malignancy or metastatic tumor. Furthermore, histopathological results of the biopsies of the hepatic mass, mediastinal mass, and prostatic mass demonstrated granulomatous inflammation. Therefore, metagenomic next-generation sequencing (mNGS) was utilized to confirm the diagnosis. Mycobacterium tuberculosis complex was simultaneously detected in the spinal surgical resection specimens and bronchoalveolar lavage fluid (BALF), indicating the diagnosis of disseminated TB. mNGS is an emerging molecular diagnostic technology, and its application in disseminated TB has been rarely reported. We highlight that disseminated TB should be considered even in an immunocompetent patient, and mNGS can be performed when the diagnosis is difficult.

Clinical staging of malignant pleural mesothelioma: current perspectives

Malignant pleural mesothelioma (MPM) is a disease with limited therapeutic options, the management of which is still controversial. Diagnosis is usually made by thoracoscopy, which allows multiple biopsies with histological subtyping and is indicated for staging purposes in surgical candidates. The recommended and recently updated classification for clinical use is the TNM staging system established by the International Mesothelioma Interest Group and the International Association for the Study of Lung Cancer, which is based mainly on surgical and pathological variables, as well as on cross-sectional imaging. Contrast-enhanced computed tomography is the primary imaging procedure. Currently, the most used measurement system for MPM is the modified Response Evaluation Criteria in Solid Tumors (RECIST) method, which is based on unidimensional measurements of tumor thickness perpendicular to the chest wall or mediastinum. Magnetic resonance imaging and functional imaging with ¹⁸F-fluoro-2-deoxy-D-glucose positron-emission tomography can provide additional staging information in selected cases, although the usefulness of this method is limited in patients undergoing pleurodesis. Molecular reclassification of MPM and gene expression or miRNA prognostic models have the potential to improve prognostication and patient selection for a proper treatment algorithm; however, they await prospective validation to be introduced in clinical practice.

Case report: multiple systemic disseminated tuberculosis mimicking lymphoma on 18F-FDG PET/CT

RATIONALE

F-fluorodeoxyglucose positron emission tomography/computed tomography (F-18 FDG PET/CT) has an important role in the diagnosis of various malignancies. However, F-18 FDG can also exhibit intense accumulation in tissues in inflammatory conditions such as active tuberculosis (TB) and sarcoidosis.

PATIENT CONCERNS

We report a case of a 52-year-old female with irritable cough. CT showed a lung mass with multiple bilateral lung nodules, and sarcoidosis was suspected. F-18 FDG PET/CT was undertaken for the diagnosis and showed intense uptake of FDG in the mass in the lower lobe of the right lung, multiple lymph nodes, liver, and spleen. The maximum standardized uptake value of F-18 FDG was 43.58. This pattern of involvement most likely represents lymphomatous involvement.

DIAGNOSES

Histopathology suggested tubercular involvement.

INTERVENTION AND OUTCOMES

The patient received anti-TB treatment and recovered.

LESSONS

Abovementioned extent and distribution of F-18 FDG in tubercular lesion is relatively rare, thus, one must be observant and aware with regards to TB being a strong mimic of lymphoma in endemic regions.

Assessment of Therapy Response by FDG PET in Infection and Inflammation

Positron emission tomography (PET) is a well-known imaging modality in assessing the treatment response to chemotherapy or radiotherapy in various malignancies. A systematic review of the literature reveals a few publications reporting evaluation of the treatment response in benign conditions using PET/computed tomography. PET holds a promising future role in the follow-up of inflammatory or infectious diseases. In this article, [(18)F]Fluorodeoxyglucose PET as a tool in the evaluation, treatment, and follow-up of infectious and inflammatory diseases is discussed.

Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography imaging in response monitoring of extra-pulmonary tuberculosis

Positron emission tomography/computed tomography (PET/CT) using 2-deoxy-2-(fluorine-18) fluoro-D-glucose (¹⁸F-FDG) has become a standard diagnostic modality in oncological practice. F18-FDG PET/CT is sensitive in detecting malignancy; however, specificity is low in differentiating infections or inflammatory diseases from tumor. In the present case study, we report a patient with postoperative carcinoma of tongue presenting with cervical lymphadenopathy and fever. The PET/CT scan showed metabolically active generalized lymphadenopathy, and a possibility of lymphoma was suggested. Fine needle aspiration cytology showed the Ziehl–Neelsen staining to be strongly positive for acid-fast bacilli and first line of antitubercular drug was administrated. Six months later after the initiation of therapy, a follow-up PET/CT showed remarkable improvement of the disease status. This case study illustrates that tubercular infection can be a pitfall in F18-FDG PET/CT imaging. PET positive lesions do not always indicate malignancy, and histological confirmation of lesions with biopsy should always be performed. Once diagnosed to be tubercular, FDG PET/CT is a powerful imaging tool in monitoring the therapy.

Rare solitary focal tuberculous involvement of liver masquerading as hepatic metastasis on FDG PET/CT in a case of fibular round cell tumor

Finding of focal 18F-fluoro-deoxyglucose (FDG) uptake in liver on FDG positron emission tomography/computed tomography (FDG PET/CT) in a known case of malignancy is often considered to be metastases. We report a similar finding on FDG PET/CT in a case of Ewing's sarcoma of thigh, which turned out to be of tuberculous etiology, an unusual cause of false positive FDG uptake in the liver.

Neoplasm-like abdominal nonhematogenous disseminated tuberculous lymphadenopathy: CT evaluation of 12 cases and literature review

AIM: To assess the diagnostic value of computed tomography (CT) imaging in screening for abdominal nonhematogenous disseminated tuberculous lymphadenopathy (TL).

METHODS: The CT scans of 12 patients with abdominal nonhematogenous disseminated TL suggestive of neoplasm were retrospectively analyzed in this review. The final diagnoses were confirmed by lymph node pathology for seven patients and by laparoscopic surgery for five patients. All of the patients were treated at our institution between April 1995 and August 2009.

RESULTS: The sites of involvement were the periportal (n = 6), peripancreatic (n = 3), periaortic (n = 3), and mesenteric (n = 2) regions. On the plain CT scan, the lymphadenopathy showed a heterogeneous isodensity or hypodensity in 11 patients and a low density in one patient. Peripheral enhancement was observed on the dynamic contrast-enhanced CT scans for all patients. In two cases, scans were more revealing during the portal venous and delayed phases.

CONCLUSION: Abdominal lymphadenopathy with predominant peripheral rim-like enhancement on the dynamic contrast-enhanced CT scan may suggest a diagnosis of TL.

Tuberculosis and malignancy

BACKGROUND

Tuberculosis (TB) and malignancy represent global threats claiming millions of lives and inflicting formidable suffering worldwide. Surprisingly, the pathophysiological and practical implications of their co-existence have received little attention.

METHODS

Therefore, we sought to review the available literature on the field and identify data regarding the association between TB and malignancy in order to highlight the neglected aspects of this association and probably derive clinically useful information. We searched PubMed up to June 2008 for case reports, case series, non-comparative and comparative studies that were written in English and reported data on the occurrence of both TB infection and a neoplastic disorder in the same patient(s). The development of mycobacterial infections in patients with immunocompromized conditions is well known and was considered outside the scope of this review.

EVIDENCE SYNTHESIS

The synthesis of the available evidence enabled us to establish three different types of association between malignancy and TB: (i) the development of cancer on the background of a previous tuberculous infection; (ii) the concurrent existence of TB and malignancy in the same patient(s) or clinical specimen(s); and (iii) the diagnostic challenges arising from the multi-faceted presentations of these two disorders.

CONCLUSION

We conclude that clinicians need to be aware of the protean manifestations of TB and cancer and maintain a high index of suspicion for simultaneous and/or misleading presentations. In addition, further research is required to determine if a tuberculous infection, being similar to other chronic infections and inflammatory conditions, may facilitate carcinogenesis.