Case Description
A 12-year-old boy with recent poor weight gain and vague abdominal pain was found to have microcytic anemia during the work-up of his short stature. He denied fevers and night sweats. Blood work showed anemia (6.3 gm/dL), low MCV (61 fL), leukopenia (2.5 × 103/μL), neutropenia (0.5 × 103/μL), thrombocytosis (401 × 103/μL), low serum iron (21 μg/dL), normal TIBC (298 μg/dL), normal ferritin (271 ng/mL), elevated haptoglobin level (347 mg/dL) and a negative IgG DAT. Hemoglobin electrophoresis was negative for hemoglobinopathy.  Peripheral blood smear revealed reactive lymphocytes. EBV IgG and IgM were positive. Parvovirus, HIV, and CMV were negative.  Chest x-ray and thyroid studies were normal. Baseline autoimmune workup (RF, dsDNA, ANA as well as tTG-IgA for celiac disease) was negative. Uric acid and LDH were normal. CRP (118 mg/L) and ESR (143 mm/h) were elevated.
He was referred to oncology after an ultrasonography of the patient’s abdomen demonstrated an ill-defined abdominal mass. A subsequent MRI of the abdomen and pelvis revealed a solid, minimally enhancing 5 × 3.6 × 4.3 cm retroperitoneal mass in the left para-aortic/mesenteric root region, just below the inferior border of the pancreas (Figure 1) . Fine-needle aspiration of the mass showed reactive/benign lymphoid proliferation with focal CD21-, CD35-, and D2-40+ dendritic meshwork, no immunophenotypic support for B-cell or T-cell neoplasia and Castleman disease could not be excluded. Positron emission tomography/computed tomography (PET/CT) scan demonstrated a unifocal, 4.5-cm lesion with a standardized uptake value of 8.5 (Figure 1 ). Given the concern for Castleman disease, the patient underwent laparoscopic resection of the mass. Pathology showed changes indicative of HVV CD (Figure 2) .
Within 2 months of the resection, the patient’s IL-6 level decreased from 21 pg/mL to undetectable, hemoglobin level normalized, CRP level declined from 118 mg/L to 0.6 mg/L, and sedimentation rate decreased from 143 mm/h to 7 mm/h. PET/CT scan 1 month after excision showed no recurrence or new lesions. The patient’s laboratory values remained normal (HB 11.2g/dL, MCV 82fL) at last follow-up, 24 months after resection.