PO23 - Clinical Application of Serum Lymphopenia in Sarcoidosis Evaluation: Can It Serve as a Marker of Disease Extent and Disability?
Anna Goljan Geremek (Poland)1; Patrycja Nejman Gryz (Poland)1; Malgorzata Kobylecka (Poland)1; Elzbieta Puscinska (Poland)2; Agnieszka Kolodzinska (Poland)1; Renata Glowczynska (Poland)1; Sonia Borodzicz Jazdzyk (Poland)1; Joanna Zuchowska (Poland)1; Katarzyna Romanowska Prochnicka (Poland)1; Marta Maskey Warzechowska (Poland)1; Julia Rutkowska (Poland)1; Lena Kalinowska (Poland)1; Jolanta Kunikowska (Poland)1; Rafal Krenke (Poland)1;
1 - Medical University of Warsaw; 2 - Institute of TB and Lung Diseases Warsaw;
Keywords: sarcoidosis; [18F] FDG PET/CT; lymphopenia;
Select the theme: Challenges in Sarcoidosis Diagnosis and Staging
Type: Original Papers
Presentation: Poster Presentation

Introduction: Peripheral lymphopenia in sarcoidosis results from lymphocyte migration to sites of inflammation.



Objectives: To determine whether peripheral lymphopenia could serve as a laboratory marker useful in assessing the severity and extent of sarcoidosis.



Materials and Methods: Eighty-four patients participating in a diagnostic accuracy study of [18F] FDG PET/CT for evaluating disease activity and multi-organ involvement in sarcoidosis underwent routine laboratory tests, including complete blood count and routine pulmonary function tests. Carb-free [18F]FDG PET/CT whole-body scans were performed in 84 steroid naïve patients.  PET/CT images were qualitatively analyzed to assess the presence of active organ lesions. 

Results: Lymphopenia was identified in 55 patients. Compared to patients with normal white blood cell counts, those with lymphopenia were younger at sarcoidosis diagnosis (<40 years; p=0.04), had significantly lower BMI (p=0.02), significantly worse spirometry results (both FEV1 and FVC as percent predicted and z-scores), and showed a trend toward restriction on plethysmography (p=0.08). Patients with lymphopenia had significantly higher serum gamma-globulin levels (p=0.05). Patients were stratified by metabolic activity patterns on [18F] FDG PET/CT into groups: 

• With vs. without metabolically active pulmonary changes 

• With metabolically active extrapulmonary changes vs. isolated pulmonary activity 

• With vs. without metabolic activity, regardless of organ location 

Lymphopenia was significantly more frequent in patients with [18F] FDG-avid metabolically active pulmonary sarcoidosis compared to those without active pulmonary changes in PET/CT scans (p=0,03),  in those with [18F] FDG-avid metabolically active-multiorgan sarcoidosis vs. isolated pulmonary sarcoidosis (p=0,0006) and showed a trend toward [18F] FDG-avid metabolically active sarcoidosis, regardless of lesion location(p=0,06) 



Conclusions: In young patients (<40 years) with sarcoidosis and peripheral lymphopenia, [18F] FDG PET/CT  imaging is warranted to assess for multi-organ involvement. This approach is supported by associations with younger age at diagnosis, impaired lung function, elevated serum gamma-globulins, and higher prevalence of metabolically active disease on PET/CT—findings that may guide escalation to systemic therapy.