FDG-PET/ CT for initial staging and response assessment in Castleman disease - retrospective single-center study of 29 cases.

BACKGROUND Castleman disease (CD) is a rare lymphoproliferative disorder including unicentric and multicentric forms which can further be divided into four histopathologic variants (hyaline vascular, plasma cell, mixed, and plasmablastic). Multicentric CD typically behaves as an aggressive, relapsing entity with generalized lymphadenopathy and systemic symptoms. PET/CT following 18F-fluorodeoxyglucose administration (FDG-PET/CT) represents an imaging modality commonly used in malignant lymphomas for staging purposes and response assessment. However, literature data on its role in CD have been limited. PATIENTS AND METHODS Twenty-nine patients, 18 men and 11 women, dia-gnosed in 1998-2016 were enrolled in our retrospective study. All patients underwent FDG-PET/CT during initial staging and/or as part of response assessment. We measured the maximum diameter of a lesion and established an index value corresponding to the ratio of the maximum standardized uptake value for the observed lesion and for the liver. The information about imaging examinations, patients, and disease extensions was put in a registry and statistically analyzed. RESULTS Unicentric and multicentric CD was dia-gnosed in 17 and 12 patients, respectively. Median age at the dia-gnosis was comparable between the two groups (51 and 58 years, respectively; P = 0.352). The majority of patients with multicentric CD (83%) were men. In women, the unicentric form prevailed (82 vs. 18%) while the difference between the two forms was of borderline significance in men (44 vs. 56%; P = 0.064). Most of the patients (88%) with unicentric CD had the hyaline vascular pathology type. On the contrary, the plasma cell type was predominant in multicentric CD (42%). The most commonly included anatomic sites included the retroperitoneum (52%) and the thorax (43%). Inguinal node involvement developed only in patients with multicentric CD. In repeatedly examined patients, FDG-PET/CT demonstrated a progressively decreasing size and metabolic activity of a selected lymph node. CONCLUSION FDG-PET/CT represents a suitable modality for initial staging and response monitoring of CD, especially in patients with a multicentric form.