Immunological and Hematological Findings Associated with Thymic Epithelial Neoplasms
Authors: Khawaja Muhammad Rizwan , Miller Nicholas J , Loehrer Patrick J , Nelson Robert P. 
Published: October 2019

Abstract
Abstract 1742

Introduction:
Although it is well known that thymic epithelial neoplasms are associated with autoimmune and manifestations of immunodeficiency, the extent to which abnormatilies in clinical hematological or immunological function occur in this population has not been completely documented. This retrospective study aimed to characterize the clinical hematological and immunological features of patients with thymic epithelial neoplasms.

Methods:
From a cohort of 512 patients with thymic epithelial neoplasms, 79 patients (33 males, 46 females) with diagnosed autoimmune/immunodeficiency conditions or signs and/or symptoms suggesting an autoimmune or immunodeficiency state were evaluated by standard immunogical and hematological testing. “Autoimmune conditions” included myasthenia gravis, pure red cell aplasia (PRCA), thyroiditis/hypothyroidism, glomerulonephritis, Sjõgren's syndrome, systemic lupus erythematosus, transverse myelitis, Issac's syndrome, Raynaud's disease, granuloma annulare, vitiligo, alopecia, dermatomyositis, Morvan's syndrome and chronic urticaria. Conditions designated as “immunodeficiencies” included Good's syndrome, onychomycosis, recurrent oral candidiasis, herpes zoster and opportunistic infections designated as AIDS-defining illnesses. Results were collected and tabulated from data in the electronic medical record CareWeb™, the web browser version of the Regenstrief Medical Records System of the Indiana University and Melvin and Bren Simon Cancer Center.

Results:
Pure red cell aplasia (PRCA) was present in 6 (7.6%) and Good's syndrome in 7 (8.9%) patients. Cytopenias were diagnosed in 40 (50.6%); anemia in 25 (31.6%); leucopenia in 12 (15.2%) and thrombocytopenia in 7 (8.9%) patients. IgG, IgA and IgM levels were low in 12 (15.2%), 9 (11.4%) and 15 (18.9%) patients respectively. Quantification of peripheral blood lymphocyte immunophenotypes revealed increases in CD2+ (n=44; 57.1%), CD3+ (n=33; 41.8%) and CD8+ (32; 40.5%) cell percentages and decreases in CD4+ (25; 31.6%) and CD19+ (36; 46.2%) cell percentages. Inverted CD4/CD8 ratios were present in 18 (23.7%) patients. The presence of “immunodeficiency condition(s)” was associated with a high CD8+ percentage (p=0.040), low CD19+ percentage (p=0.025) and an inverted CD4/CD8 ratio (p=0.034). The presence of an “autoimmune condition(s)” was associated with a high/normal CD4+ percentage (p=0.038). A high CD2+ percentage was associated with lower mean IgG and IgA levels (p=0.030 and p=0.017, respectively). Patients with high CD3+ and CD8+ percentages had lower mean IgA levels (p=0.046 and p=0.013, respectively). A low CD19+ percentage was strongly associated with lower mean IgG and IgA levels (p=0.004 and p=0.001, respectively). No associations were observed between lymphocyte subpopulation percentages and mean serum IgM levels.

Conclusion:
Although we observed a number of patients with PRCA and Good's syndrome, this selected cohort of patients with thymic epithelial neoplasms had a broad spectrum of cytopenias and concomitant autoimmune/immunodeficiency conditions. We observed high T cell percentages and low B cell percentages compared to adult normal values. High T cell profiles were commonly attributed to increased CD8+ percentages. Patients with autoimmune conditions are more likely to have normal or high CD4+ percentages; patients with clinical immunodeficiencies are more likely to have high CD8+, low CD19+ percentages and inverted CD8/CD4 ratios. These observations suggest a role for the assessment of immunoglobulin levels and lymphocyte immunophenotypes in patients with thymic epithelial neoplasms and associated immune mediated conditions.

Disclosures:
No relevant conflicts of interest to declare.