BackgroundRhabdomyosarcoma (RMS) is a common pleomorphic malignant soft tissue sarcoma in children and adolescents that originates from rhabdomyoblasts or mesenchymal precursor cells. Alveolar rhabdomyosarcoma (ARMS) mostly occurs in adolescents aged 10–15 years and is characterized by more aggressive behaviors and worse prognosis than other sarcomas, prone to lymphatic and hematogenous metastasis in the early stage as well as metastasizing to breast, testis, pancreas, and other parts. ARMS often occurs in the limbs and genitourinary system, however, head and neck ARMS are relatively rare when involving the nasal cavity or sinuses. The role of MRI and 18F-FDG positron emission tomography combined with computed tomography (PET/CT) remains to be established in ARMS.Case reportCase 1: An 18-year-old male was found with a left submandibular mass of approximately 1 cm in diameter 2 months ago, which gradually increased in size. CT showed multiple soft tissue masses in maxillofacial and neck regions and the lesions invaded the frontal lobe and the inner wall of the left orbital lobe. MRI showed the masses with hypointensity on T1WI, hyperintensity on T2WI, and diffusion-weighted imaging (DWI) with significant enhancement. 18F-FDG PET/CT showed multiple hypermetabolic lesions located in the maxillofacial, neck region, 3rd lumbar vertebra, and the right sacrum. A nasal endoscopic tumor biopsy and molecular testing finally helped to diagnose the ARMS. Case 2: A 14-year-old male presented with left maxillary pain with nasal congestion and left ocular swelling 15 days ago. CT demonstrated a soft tissue mass in the nasal cavity and sinuses with local protrusion into the left orbit. MRI showed the masses with a slightly low signal on T1WI, a high signal on T2WI, and DWI with significant heterogenous enhancement. 18F-FDG PET/CT showed hypermetabolic lesions in the left maxillofacial and neck regions. ARMS was finally diagnosed by a nasal endoscopic tumor biopsy and molecular testing. The patient had a recurrence of the lesion after chemotherapy and surgical resection and is currently undergoing radiation therapy.ConclusionNasal sinus ARMS is highly malignant with a poor prognosis. Accurate diagnosis relies not only on histopathology and immunohistochemistry examination but also on genetic detection of characteristic chromosomal translocations and fusion genes. Imaging methods, such as MRI and PET/CT can accurately assess the extent of the lesions and metastases, assist in the diagnosis of the disease and the selection of treatment regimens, provide precise localization for surgery, and help with treatment monitoring and follow-up.

ObjectivePrimary pulmonary nucleoprotein of the testis (NUT) carcinoma is very rare in the clinic. In this study, the clinicopathological manifestations and imaging features of the primary pulmonary NUT carcinoma were investigated to improve the diagnosis of this disease.MethodsSix patients with pathologically diagnosed pulmonary NUT carcinoma were analyzed, including three males and three females, aged 19–64 (49.00 ± 16.40) years, with clinical manifestations of cough in two cases, hoarseness in one case, blood in sputum in one case, chest pain in one case, and physical examination findings in one case, with a disease duration of 5 days to 4 months. The clinical and imaging data including CT and PET/CT were retrospectively analyzed. Further literature reviews were analyzed in both pulmonary and extrapulmonary NUT carcinoma cases who performed 18F-FDG PET/CT.ResultsMost of the patients with pulmonary NUT carcinomas presented as heterogeneous lobulated masses (83.33%), four cases (66.67%) were located in the upper lobe of the left lung, one case (16.67%) in the middle lobe of the right lung, and one case (16.67%) in the lower lobe of the right lung, with the maximum diameter ranging from 1.30 to 8.90 cm and the median of 3.55 cm, most of them were irregularly shaped, with more lobulated margins and more heterogeneous density (83.33%), and the enhancement was mild. PET/CT showed increased 18F-FDG uptake in the lesion and metastatic areas. Both the pulmonary NUT patients in this study and literature reviews showed the SUVmax of the tumor ranged from 5 to 40 with an average value of 12.8, whereas that of extrapulmonary lesions had a range of SUVmax at 4.5–64.1 and a mean of 13.8.ConclusionIn patients with central lung masses, rapid disease progression, and poor response to initial treatment, the possibility of NUT cancer should be considered and anti-NUT monoclonal antibody immunohistochemical staining, combined with genetic detection, if necessary, should be performed as soon as possible. CT and PET/CT imaging are essential for the staging, management, treatment response assessment, and monitoring of pulmonary NUT cancer.

BackgroundMyxoid liposarcoma (MLS) is a rare malignant soft tissue sarcoma that predominantly manifests in the deep soft tissues of the extremities, particularly within the musculature of the thigh. Unlike other types of liposarcoma, MLS demonstrates a propensity for metastasis to atypical sites, including the lung parenchyma, soft tissues, retroperitoneum, mediastinum, breast, liver, thymus, lymph nodes, and bones. The definitive diagnosis primarily relies on histology with HE staining. Imaging modalities such as ultrasound, CT, MRI, and 18F-FDG PET/CT scans serve as valuable tools for tumor identification.Case reportA 57-year-old man presented with symptoms of abdominal distention and vomiting 1 month ago. Contrast-enhancement CT revealed a heterogeneous hypodense mass in the upper-middle part of the left kidney, displaying irregular morphology and protrusion towards the exterior of the kidney, with abundant blood supply and had a maximum dimension of approximately 10.7 cm × 9.0 cm. Additionally, a rounded soft tissue density was identified in the pancreatic body. Multiplanar reconstruction demonstrated a connection between the pancreatic lesion and the kidney mass. 18F-FDG PET/CT was conducted for staging, revealing significant growth of the lesion in the upper-middle part of the left kidney, extending beyond the kidney and infiltrating the pancreatic body. The lesion demonstrated remarkably high 18F-FDG uptake (SUVmax = 10.2, MTV = 136.13 cm3, TLG = 484.62). The postoperative pathological examination confirmed the diagnosis of MLS. On the 10th day post-surgery, the patient presented with tumor recurrence and underwent another surgical resection. Unfortunately, during the operation, the patient experienced a sudden cardiac arrest and died.ConclusionRenal MLS with invasion into the pancreas is very rare in clinical practice. Due to the limited research on the utilization of 18F-FDG PET/CT in this particular context, given the rarity and low incidence of MLS, its role remains largely unexplored. As PET/CT imaging becomes increasingly prevalent, thorough imaging of disease sites becomes indispensable for the development of treatment protocols and the monitoring of treatment response.

BackgroundExtranodal natural killer/T-cell lymphoma (ENKTCL) is a distinct pathological entity and accounts for ~10% of T-cell lymphomas. The histological features of ENKTCL include angiodestruction and coagulative necrosis and the association with EBV infection. ENKTCL is typically aggressive and mainly affects the nasal cavity and nasopharyngeal region. However, some patients can present with distant nodal or extranodal involvement such as the Waldeyer ring, gastrointestinal tract, genitourinary organs, lung, thyroid, skin, and testes. Compared to ENKTCL of nasal type, primary testicular ENKTCL is very rare and has a lower age of onset and faster clinical progression, with tumor cell dissemination occurring early in the disease.Case reportCase 1: A 23-year-old man presented with 1 month of right testicular pain and swelling. Enhancement CT revealed increased density in the right testis, uneven increased enhancement, discontinuity of the local envelope, and multiple trophoblastic vessels in the arterial phase. Testicular ENKTCL was diagnosed by post-operative pathology. The patient underwent a follow-up 18F-FDG PET/CT imaging 1 month later and found elevated metabolism in the bilateral nasal, left testicular, and right inguinal lymph nodes. Unfortunately, the patient received no further treatment and died 6 months later. Case 2: A 2-year-old male child presented with an enlarged right testicle, MRI showed a mass in the right epididymis and testicular area, which showed low signal on T1WI, high signal on T2WI and DWI, and low signal on ADC. Meanwhile, CT showed soft tissue in the lower lobe of the left lung and multiple high-density nodules of varying sizes in both lungs. Based on the post-operative pathology, the lesion was diagnosed with primary testicular ENKTCL. The pulmonary lesion was diagnosed as hemophagocytic lymphohistiocytosis associated with EBV infection. The child was given SMILE chemotherapy, but pancreatitis was induced during chemotherapy, then he died 5 months later after chemotherapy.ConclusionPrimary testicular ENKTCL is very rare in clinical practice, typically presenting as a painful testicular mass, which can mimic inflammatory lesions and cause diagnostic challenges. 18F-FDG PET/CT plays pivotal roles in the diagnosis, staging, evaluation of treatment outcomes and prognosis evaluation in patients with testicular ENKTCL, and it is helpful to assist clinical practice to better formulate individualized treatment plans.