UNASSIGNED: A 46-year-old woman underwent surgery for parathyroid carcinoma 2 years ago. During follow-up, the patient presented with elevated parathyroid hormone (127.50 pg/mL; normal, 15-65). No abnormal uptake of 18 F-FDG or 11 C-choline was observed on 18 F-FDG and 11 C-choline PET/CT imaging. The patient was enrolled in a clinical trial for 18 F-FAPI PET/CT imaging, revealing a lesion with intense focal uptake within the left sternocleidomastoid muscle. The patient underwent surgery. Postoperative pathology and immunohistochemical analysis confirmed parathyroid carcinoma metastasis.

Mesenchymal chondrosarcoma (MCS) is an aggressive malignant mesenchymal tumour of uncertain differentiation. This is rare, accounting for 2%-4% of chondrosarcomas. Its peak incidence is in the second and third decades, though it can occur at any age. These tumours show a widespread distribution, mainly in bone, but with approximately 40% affecting somatic soft tissue. We present a case of MCS arising within the soleus muscle. The lesion was surrounded by a split-fat sign/fatty rind which is a typical feature of peripheral nerve sheath tumours or other benign intramuscular tumours. However, percutaneous biopsy showed MCS. We highlight how perilesional fat is not exclusive to benign intramuscular lesions and, although much less common, can be associated with malignant lesions. This is, to the best of our knowledge, the first reported case of MCS presenting with a split-fat sign at MRI.

Background: Esophageal cancer (EC) comprises 1% of all diagnosed cancers in the USA. It is more common in other parts of the world. If there is distant metastasis, the relative survival rate is 6%. There are no standardized screening methods for EC. Case Presentation: We reported a four-year case of esophageal cancer, a P53-positive mutation with atypical distant metastasis to the cardiac and skeletal muscles. The patient was managed with multimodal therapy, including immunotherapy, which could have been a factor in prolonged survival. Conclusions: Distant metastases are typically seen postmortem, and with prolonged survival, we are able to find such unique metastases antemortem. Despite a history of negative scans, the patient\'s ctDNA (circulating tumor DNA) remained positive, which was a better predictor of recurrence in this case. Future research is required to establish cost-effective screening methods and standardized treatments.

BACKGROUND: Intramuscular hemangiomas (IMH) account for 0.8 % or less of all benign soft tissue tumors in the general population. Due to their uncommon nature, especially in the head and neck, they are often misdiagnosed and not included in the differential diagnosis.
METHODS: This study describes a case series of eleven pediatric patients with a diagnosis of IMH through a retrospective review of the electronic health records and archival records in the Department of Pathology at Children\'s Hospital of Colorado (CHCO).
RESULTS: The index case had a unique presentation in the submandibular triangle, while the remaining ten cases are appendicular and thoracolumbar in nature.
CONCLUSIONS: This case series contributes to the sparse scientific literature available regarding IMH, particularly in its head and neck presentation as relevant to otolaryngologists.

Skeletal muscle (SKM), despite comprising ~40% of body mass, rarely manifests cancer. This review explores the mechanisms that help to explain this rarity, including unique SKM architecture and function, which prohibits the development of new cancer as well as negates potential metastasis to SKM. SKM also presents a unique immune environment that may magnify the anti-tumorigenic effect. Moreover, the SKM microenvironment manifests characteristics such as decreased extracellular matrix stiffness and altered lactic acid, pH, and oxygen levels that may interfere with tumor development. SKM also secretes anti-tumorigenic myokines and other molecules. Collectively, these mechanisms help account for the rarity of SKM cancer.

UNASSIGNED: Primary skeletal muscle lymphoma is rare. We describe 18 F-FAPI-42 and 18 F-FDG PET/MRI findings in a case of primary peripheral T-cell lymphoma of the skeletal muscles with brain involvement. The multiple skeletal muscle tumors and one larger cerebral tumor showed intense FDG uptake and mild to moderate FAPI uptake. FDG PET was superior to FAPI PET in delineating the muscle tumors because of significantly higher FDG uptake of the muscle tumors than FAPI uptake. FAPI PET was superior to FDG PET in delineating the cerebral lesion because of a very low background FAPI activity in the brain parenchyma.

METHODS: We report a case of an intramuscular thigh hemangioma in a 19-year-old woman with a several year history of atraumatic thigh pain. Radiographs obtained by her primary care physician demonstrated periosteal bone reaction, prompting referral to Orthopaedic Oncology department. The patient had successful symptomatic management with propranolol.
CONCLUSIONS: The case highlights the diagnosis and potential treatments. In a stepwise approach to care for symptomatic benign vascular lesions, propranolol has been a proven therapeutic option and may be a useful first-line therapy for symptomatic hemangiomas.

We detail a case of a woman in her 40s with isolated melanoma skeletal muscle metastasis (MSMM) to the right psoas muscle. This patient underwent R0 surgical resection through a novel pelvic approach. She received subsequent adjuvant immunotherapy with Braftovi/Mektov along with adjuvant radiation. She is currently disease free at 9 months post surgery. Here, we describe our novel surgical approach including description of the tumour pathology. We explain our multidisciplinary management of MSMM consisting of a multidisciplinary surgical approach by surgical oncology, gynecological oncology and urology as well as multidisciplinary medical management by oncology, radiation oncology and pathology. Finally, we discuss best current options for therapeutic management.

The patient presented to the clinic with painful muscle swelling in the right lower extremity, which improved with immunosuppressive therapy. Initially, the condition was diagnosed as polymyositis but recurred soon after. After imaging and biopsy, the final diagnosis was primary skeletal muscle peripheral T-cell lymphoma, not otherwise specified (PSM-PTCL, NOS). In this report, we discuss the challenges in diagnosing and treating this aggressive malignancy and review the literature on PSM-PTCL, NOS. Key Points • To date, there are few reports of PSM-PTCL, NOS, and our case is the tenth. • It is crucial to consider PSM-PTCL, NOS, when presenting with localized muscle edema and unexplained pain. • Histopathological examination is likely the most effective method for diagnosing this rare disease.

Although hemangiomas are the most common soft tissue tumors, intramuscular hemangiomas account for only 0.8% of all vascular tumors. These lesions are rarely located adjacent to the bone and cause changes in the adjacent bone. They are often mistakenly diagnosed as bone tumors. In this study, a case of a 19-year-old male patient with intramuscular hemangioma causing cortical thickening was reported.