Diagnostic Approaches to Neuroendocrine Neoplasms of Unknown Primary Site

Erythema nodosum as first clinical manifestation of metastatic neuroendocrine tumor: A case report

Erythema nodosum (EN) is a reactive inflammatory panniculitis, which has been associated with medications, infections, autoimmune and autoinflammatory diseases. It has rarely been associated with neoplasms. We present the case of a 61-year old woman who was admitted because 3-week history of painful erythematous subcutaneous nodules on the lower limbs clinically consistent with EN, which was confirmed by skin biopsy. The patient denied use of medication. No general or systemic symptoms were present. As part of his study, an abdominal ultrasound and later magnetic resonance imaging (MRI) was done and lesions suggestive of liver metastases were reported. An ultrasound guided liver biopsy was then performed and pathology studies evidence a well differentiated grade II gastro-enteropancreatic neuroendocrine tumor (GEP-NET). A 9mTc-Octreotide scintigraphy evidenced a positive expression of somatostatin receptor in the liver and in a nodular mesenteric lesion in contact with an intestinal loop. The patient began treatment with lanreotide and was scheduled for cytoreductive surgery. During surgery, 50 cm of the small intestine, gallbladder, mesenteric fat and a 4.2x3.3 × 1 cm tumor located on the VII hepatic lobe were resected. Subsequently EN lesions of the lower extremities resolved. We present a rare case of GEP-NET-associated EN, that improved with surgical tumor cytoreduction and hormone therapy.

Dual-Energy CT in Oncologic Imaging

Dual-energy CT (DECT) is an innovative technology that is increasingly widespread in clinical practice. DECT allows for tissue characterization beyond that of conventional CT as imaging is performed using different energy spectra that can help differentiate tissues based on their specific attenuation properties at different X-ray energies. The most employed post-processing applications of DECT include virtual monoenergetic images (VMIs), iodine density maps, virtual non-contrast images (VNC), and virtual non-calcium (VNCa) for bone marrow edema (BME) detection. The diverse array of images obtained through DECT acquisitions offers numerous benefits, including enhanced lesion detection and characterization, precise determination of material composition, decreased iodine dose, and reduced artifacts. These versatile applications play an increasingly significant role in tumor assessment and oncologic imaging, encompassing the diagnosis of primary tumors, local and metastatic staging, post-therapy evaluation, and complication management. This article provides a comprehensive review of the principal applications and post-processing techniques of DECT, with a specific focus on its utility in managing oncologic patients.