Background Ewing’s sarcoma is categorized as small round cell aggressive tumor which commonly occurs in bone and soft tissue. Primary renal Ewing’s sarcoma is an extremely rare entity and accounts for less than 1% of renal masses. It is characterized by a very aggressive course, with very few reported cases in the literature. Primary renal Ewing’s sarcoma is indistinguishable from renal cell carcinoma on anatomical imaging and therefore need histopathological correlation for confirmation. The positron emission tomography (PET) fused with computed tomography (CT) helps in the evaluation of disease, for staging and metastatic workup. Case presentation We present a case of 48-year-old lady who presented to urology department with difficulty in passing urine for 5 months associated with pain in the right flank region. She had an episode of haematuria 5 months back. Contrast enhanced CT showed a large lobulated heterogeneously enhancing right retroperitoneal mass in renal fossa. Histopathological examination and immunohistochemistry were suggestive of Ewing’s sarcoma. The PET/CT revealed FDG avid right renal mass with lymph nodal and skeletal metastasis. Conclusions Ewing’s sarcoma being aggressive tumour usually present with bone, liver and lung metastasis along with lymph nodal metastasis at time of diagnosis. The 18 F FDG PET/CT helps in diagnosis, staging, appropriate treatment planning, restaging, response evaluation and prognostication of Ewing’s sarcoma.

Background Ewing sarcoma and peripheral primary neuroendocrine tumors are aggressive neoplasms which consist of small, round, blue cells of neuroectodermal origin. They usually arise from the skeleton and consist of genetic mutations EWSR1 in chromosome 22 and FL1 gene on chromosome 11. Extraskeletal Ewing sarcomas (EES) are rare entities with most common sites of EES being extremities, head and neck region and retroperitoneum. Posterior mediastinal Ewing sarcoma is rare. For its evaluation, 18F-fluorodeoxyglucose positron emission tomography (18F FDG PET/CT) plays significant role in staging, management planning and prognostication. Case presentation We describe a rare case of EES of posterior mediastinum in a 20-year-old boy who presented with signs of upper motor neuron lesion below D10 level. Contrast-enhanced magnetic resonance imaging (CEMRI) showed a heterogeneously enhancing posterior mediastinal mass in pre- and paravertebral region with intraspinal extension in D2-D4 levels. Fluorodeoxyglucose PET/CT showed a metabolically active mass occupying the superior, middle and posterior mediastinum on the left, displacing the trachea and esophagus toward the right side and causing complete collapse of the left lung. Posteriorly the mass was seen destroying the D2-D5 vertebrae with intraspinal extension at D2-D4 level. Metabolically active metastatic disease was seen in pleura, skull, D12 vertebra, right iliac bone and bilateral proximal femorae. Biopsy obtained from lung and adjacent pleura showed features of a round cell tumor positive for NKX 2.2, weak positive for FLI 1 and negative for PAN CK, LCA, Vimentin and TLE-1, suggestive of Ewing sarcoma. Based on these investigations, a diagnosis of EES of posterior mediastinum was made. Conclusion Extraskeletal Ewing sarcoma of posterior mediastinum is a rare and aggressive entity. Management of metastatic EES comprises radiotherapy and systemic chemotherapy which reduces tumor burden and micrometastasis. However, response to treatment in metastatic EES is poorer than in localized disease with overall 5-year survival rates of less than 30%. Fluorodeoxyglucose PET/CT can be a useful tool to accurately detect the extent of local disease in the presence of atelectasic lung for radiotherapy planning as well as evaluating response to therapy.

The thyroid cartilage metastatic involvement is an extremely rare entity. It can be asymptomatic at the earlier stage and can become symptomatic later on. Involvement of thyroid cartilage is frequent in melanoma and renal and rarely reported in an advanced stage of carcinoma prostate, breast, and lung. These cases were usually reported on positron emission tomography/computed tomography (PET/CT) as can often easily be missed on computed tomography scan alone. We present a case report of metastatic involvement of thyroid cartilage in squamous cell carcinoma of buccal mucosa detected on the whole-body 18F-fluorodeoxyglucose PET/CT.

Gallbladder carcinoma is an aggressive neoplasm that is often diagnosed only in the later stages of the disease progression. Common sites of distant metastases of primary carcinoma gallbladder include lymph nodes, peritoneum and lung. Only a few cases of metastases to adrenal glands and kidneys have been reported in literature. Cutaneous and muscular metastases from gallbladder cancer are also unusual, and an extensive literature search revealed only a few cases to date. We present two such cases of gallbladder carcinoma which presented with metastases to these rare sites at the time of diagnosis which were detected by 18 fluorodeoxyglucose positron emission tomography/ computed tomography (18F FDG PET/CT). The first case is of a 45-year-old lady who presented to the general surgery department with complaints of abdominal pain, loss of appetite and nausea for 2 months. Conventional imaging with ultrasound and contrast-enhanced computed tomography (CECT) of the abdomen showed asymmetric gallbladder wall thickening occupying the fundus and body with extensive regional lymphadenopathy. 18F FDG PET/CT revealed a metabolically active gallbladder mass with bilateral adrenal gland lesions with cutaneous, muscular and skeletal metastases. The second case is of a 35-year-old lady who complained of left upper quadrant abdominal pain and nausea for one month. Successive CECT and Magnetic Resonance Cholangiopancreatography (MRCP) studies made the radiological diagnosis of gallbladder neoplasm. Pre-operative 18F FDG PET/CT showed a metabolically active gallbladder mass with bilateral adrenal gland lesions, lymph node involvement and bilateral renal metastasis. The Third case was 75 years old male who had incidental carcinoma gall bladder on cholecystectomy and PETCT was done for staging, and it showed metabolically active liver SOL, Bilateral adrenal deposits with mediastinal abdominal, retroperitoneal and lymph nodes. The fourth case is a 55 year old female who was diagnosed as neck gall bladder wall thickening on ultrasonography on further evaluation PETCT was done which showed hypermetabolic gall bladder neck wall thickening along with bilateral adrenal lesion and abdominal, retroperitoneal and retro-crural and right supraclavicular lymph nodes. Adrenal and other metastasis detection on 18F FDG PET/CT led to a change in the management from curative surgery to palliative chemotherapy in all patients. Thus,18F FDG PET/CT is a valuable modality in such type of cases that aids decision making regarding staging, appropriate management and monitoring response to therapy.

Purpose: Incidental gallbladder carcinoma (IGBC) is identified after cholecystectomy being performed for a presumed benign disease and histopathology turns out as malignant disease. For optimal management planning, it is crucial to know the actual disease status. 18F-fluorodeoxyglucose Positron Emission Tomography/ Computed Tomography (FDG PET/CT) provides local, regional as well as distant disease i.e. restaging and identifying true burden of disease for optimal treatment planning. The aim of this study was to restage the IGBC patients on 18F FDG PET/CT and find out any change in treatment plan. Methods: This retrospective descriptive study was performed between November 2021 to February 2023. All PET/CT scans were analyzed which came for restaging in IGBC. Results: PET/CT was performed at a median time of 9 weeks (range 6 to 12 weeks) from the date of surgery. This study included 17 patients (6 male and 11 female), with a median age of 55 years (range 38 to 76 years). From total of 17 PET/CT scans, 10 (58.8%) patients were positive and 7 (41.1%) patients were negative on PET/CT. Amongst the PET/CT positive patients, disease pattern was seen in the form of local/ residual disease/ liver infiltration, regional lymph nodes and distant metastases. Among the 17 patients, treatment plan in 5 patients (having PET/CT negative) was changed from surgical intervention to no treatment, and in 2 patients (having PET/CT positive), treatment plan was changed to Chemotherapy i.e. total 7 (5+2, 41% of total 17 patients) patients’ treatment plans were changed. By reducing the number of patients undergoing re-resection, there is improvement in overall survival and it reduces the burden on already overburdened health infra-structure especially in developing countries like India where incident is high. Conclusion: PET/CT provides the actual stage of IGBC. It changes treatment plan and reduces the number of patients undergoing re-resection, thus improving overall survival. It also decreases burden on overburdened health infrastructure.