4779. Abdominal CT Findings Suggestive of Castleman Disease: Multicenter Review of 76 Adult Cases with Abdominopelvic Nodal Involvement
Authors * Denotes Presenting Author
  1. Yashant Aswani *; University of Iowa Hospitals and Clinics
  2. Vincenzo Wong; MD Anderson Cancer Center
  3. Mark Sugi; Mayo Clinic - Phoenix
  4. Vincent Mellnick; Mallinckrodt Institute of Radiology
  5. Perry Pickhardt; University of Wisconsin School of Medicine and Public Health
Castleman disease encompasses a distinct group of lymphoproliferative disorders, classified morphologically by unicentric and multicentric forms. Abdominal involvement is seen in 15 - 30% of cases. Although a hypervascular appearance at CT is a widely appreciated feature, we have also anecdotally observed prominent hazy infiltration of the perinodal fat, or “fat halo" sign, in some cases. We sought to better characterize the CT findings of Castleman disease involving the abdomen and pelvis.

Materials and Methods:
A multicenter search at five institutions yielded 76 adults (mean age, 42.1 ± 14.3 years; 38 women, 38 men) meeting the inclusion criteria of histopathologically-proven Castleman disease, with nodal involvement at abdominopelvic CT. At retrospective review, the dominant nodal mass was localized, measured for size and attenuation, and for the presence of calcification and a prominent perinodal “fat halo” appearance. Hypervascular nodal enhancement was based on both subjective and objective comparison with aortic blood pool attenuation.

Abdominal involvement was unicentric in 48.7% (37/76) and multicentric in 51.3% (39/76), including 31 cases with extraabdominal involvement. Histopathologic subtypes included the hyaline vascular variant (HVV), plasma cell variant (PCV), mixed HVV/PCV, and HHV-8 variant in 39, 25, 3, and 9 cases, respectively. The dominant nodal mass measured 4.4 ± 1.9 cm and 3.2 ± 1.7 cm in mean long- and short-axis, respectively, and appeared hypervascular in 58.6% (41/70 with IV contrast). Internal calcification was seen in 22.4% (17/76). An infiltrative perinodal fat halo sign was present in 56.6% (43/76). For the 39 HVV cases, 30 (76.9%) were unicentric, 27 (69.2%) appeared hypervascular, and 27 (69.2%) demonstrated the fat halo sign.

In addition to a hypervascular appearance, nodal masses demonstrating a prominent infiltrated halo of perinodal fat at CT may suggest the diagnosis of Castleman disease, particularly the unicentric hyaline vascular variant.