A 32-year old male presents with abdominal discomfort.
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Diagnosis: Nodal lymphoma
Plain and post-contrast CT at the level of the abdomen reveals multiple well-defined homogeneously enhancing lymph nodes in the peritoneum and retroperitoneal compartment. The vessels are seen coursing through this nodal mass with mild narrowing of caliber without invasion (sandwich sign).
Discussion
Lymphomas are defined as the clonal malignant proliferation of a mature lymphocyte from a secondary lymphoid structure, a lymph node, or an extranodal structure. They are further classified into Hodgkin’s (HD) and Non-Hodgkin’s lymphoma (NHL).
Epidemiology and Pathology
• HD has a bimodal age distribution: First peak occurs in the middle to late 20s and the second peak after the age 50. Males are affected as commonly as females
• Prevalence of NHLs increases steadily with age throughout life. M:F 2:1
Imaging Features
Ultrasound
• Initial evaluation and follow-up of involvement of superficial lymph nodes, and for testicular involvement.
• Involved nodes are seen as well-defined, rounded homogenous lesions with loss of fatty hilum.
• However, US examination may be affected by the patient’s obesity or bowel meteorism, hence cross section imaging is necessary.
CT
• Allows detailed evaluation of the mediastinum, chest wall, pulmonary parenchyma, and pleura or pericardium.
• Enlarged nodes with moderate homogeneous enhancement typically seen.
Sandwich Sign
○ Refers to the characteristic appearance of enlarged mesenteric lymphadenopathy enveloping fat and tubular structures at cross-sectional imaging resembling a sandwich or a hamburger.
○ Sign is specific to mesenteric lymphomas as they can grow to a large size and can envelop fat, bowel, and vessels without causing clinical symptoms.
○ Carcinomas, sarcomas, and carcinoid tumors originate within the small bowel and then spread to the mesenteric nodes and can quickly invade the bowel wall, causing perforation, hemorrhage, and widespread disease
MRI
• Particularly useful for evaluating the CNS disease.
• Owing to their cellular content, lymphoma deposits show restricted diffusion and have homogeneous post contrast enhancement.
FDG-PET CT
• Provides comprehensive staging of the disease process and is also useful for monitoring response to therapy
Differentials
Causes of mesenteric lymphadenopathy include lymphoma, carcinoma, sarcoma, carcinoid tumor, tuberculosis, Whipple disease, lymphadenopathy syndrome associated with acquired immunodeficiency syndrome (AIDS), and inflammatory bowel disease.
