Abdominal and pelvic lymph node involvement in non-Hodgkin lymphoma: CT manifestations in Chinese patients

Objective: To study the CT manifestations of abdominal and pelvic lymph nodes in non- Hodgkin lymphoma (NHL) of Chinese patients, and to investigate their correlation with pathology subtypes. Methods: The CT images of 241 patients with enlargement of abdominal and pelvic lymph nodes involved by NHL were reviewed. Of them, 96 patients whose clinical and imaging data fulfilled the requirement for analysis were included. According to the Clinical Schema for the Lymphoid System, patients were divided into 3 subtypes, indolent lymphoma (IL; n=31), aggressive lymphoma (AL; n=61), very aggressive lymphoma (VAL; n=2), and unclassified lymphoma (UCL; n=2), respectively. Abdominal and pelvic CT scans were undertaken in 46 patients, abdominal CT only in 47 cases, and pelvic CT only in 3 cases. CT with iv contrast administration was obtained in 80 patients. Anatomic sites involved were nominated as retroperitoneal (i.e. paraaortic), abdominal (including paracardiac, gastrohepatic, hepatic hilar, and mesenteric etc), retrocrural, diaphragmatic, common iliac, internal iliac, external iliac, and inguinal nodes, respectively. Size, number, discreteness, and density of the nodal lesions were analyzed, and correlated with pathology subtypes. The minimal dimension of the largest node was measured. Results: (1) Size: Most of the nodes were ≤2 cm in size, 60.5% (219/362 sites) in IL and AL, 56.6% (77/136 sites) in IL, and 62.8%(142/226 sites) in AL, respectively. There was no statistical significant difference of the nodal size between IL and AL in each location (χ2=0.341, P=0.559). (2) Number: Mesentery had the largest number of node involvement (6.5 vs 5 nodes on an median, IL vs AL), with retroperitoneum placed second (4 vs 4 nodes, IL vs AL. (3) Discreteness: Most of the nodes were discrete with an incidence of 77.1% (279/362 sites, IL and AL), and 74.3% (101/136 sites) in IL, 78.8% (178/226 sites) in AL, respectively. No statistical significant discrepancy was found between the two pathological patterns (χ2 = 01971 , P = 01324) 1 (4) Density: Homogeneous enhancement was the most common finding after iv contrast administration , with an incidence of 86.0% (252/293 sites IL and AL), 82.6% (100/121 sites) in IL, and 88.4% (152/172 sites) in AL, respectively, no statistical significance were found (χ2=1.936, P=0.164). Central necrosis was slightly prevalent in IL compared with AL (14 vs 12 sites), yet, there was no statistical significance (χ2=1.853, P=0.173). (5) Relationship of size and density: Nodes ≤2.0 cm were homogeneous in 97.7% (170/174 sites in IL and AL), 98.5% (67/68 sites) in IL and 97.2% (103/106 sites) in AL. For the nodes larger than 2 cm, central necrosis in IL and AL was significantly increased (χ2=27.311 and 20.807, P=0.000 and 0.000). Conclusions: (1) In NHL, abdominal and pelvic lymph node lesions were mainly homogeneously enhanced, discrete, and ≤2 cm in size. No statistical significant difference between IL lymph node and AL was demonstrated in their size, number, and discreteness. (2) The incidence of heterogeneity was obviously increased when a node was larger than 2 cm. (authors)