FRI568 Hashimoto’s Thyroiditis With Negative Antibodies In Association With Common Variable Immunodeficiency

Disclosure: I.C. Ebrahim: None. K.F. Brown: None. N.O. Vietor: None. T.D. Hoang: None. M.K. Shakir: None. Introduction: Common variable immunodeficiency (CVID) is associated with several autoimmune manifestations including Hashimoto’s thyroiditis (HT). We report a 47-year-old male with CVID and HT with negative thyroid antibodies (Abs). Case Report: A 47-year-old male, while undergoing coronary calcium scan in 2021, was found to have scattered lung nodules. Follow-up Ct scans showed interval increase in size of lung nodules and a PET scan confirmed bilateral lung nodules which demonstrated hypermetabolic activity and scattered hypermetabolic lymph nodes, suggesting infectious or inflammatory processes. PET scan also revealed thyromegaly with diffusely increased uptake, suggesting thyroiditis. Serum immunoglobulins were measured: IgA < 5 mg/dL (normal 70-400), IgG 334 mg/dL (normal 700-1600), and IgM < 25 mg/dL (normal 40-230). Serum immunoglobulins levels from depository serum samples collected in 2005 also showed similarly low values. CBC was normal, excluding any bone marrow disorders. There was no family history of immunodeficiency or thyroid disorders. On review of systems patients did not have any symptoms of hypothyroidism. Exam: thyroid 50-gms diffusely enlarged with no palpable nodules; heart and lung exam was normal. Laboratory tests including comprehensive metabolic panel, serum complement CH 50, leukemia/lymphoma panel, T/B - lymphocyte/Natkiller, CRP were all normal. Thyroid functions: TSH 5.6 mc1U/mL (0.27-4.2), Free T(4) 1.20 ng/dL (0.93-1.71), TPO Ab < 9 IU/mL (0-34), TG Ab < 1.0 1U/mL (0.0-0.9), thyrotropin receptor Ab < 0.3 IU/L (<1.0), thyroid stimulating immunoglobulin < 0.10 1U/L (0.06-0.55). Serum thyroid Ab levels from depository samples collected in 2005 also showed normal values. FNA of thyroid showed atypical lymphoid infiltrates and an excision biopsy of the thyroid isthmus confirmed lymphocytic thyroiditis. A PET avid right inguinal lymph node biopsy showed a reactive lymph node. Additional lab evaluation also showed low post vaccination pneumococcal titers. With pan-hypoglobulinemia and low vaccine response, a diagnosis of CVID was made. Patient preferred watchful waiting than iv immunoglobulin therapy. Additionally, the patient has HT with negative thyroid Abs and although patient had mild subclinical hypothyroidism patient elected no treatment. Common variable immunodeficiency (CVID) is the most frequent symptomatic primary immunodeficiency in adults. Autoimmune manifestations occur in 22% of CVID patients and these include autoimmune cytopenia, pernicious anemia, rheumatoid arthritis, vitiligo, and/or HT. Interestingly, our patient did not manifest any thyroid Abs thus it may be postulated that thyroid follicles destruction in HT is mediated predominantly by thyroid-specific B and T cells rather than by thyroid antibodies. Presentation: Friday, June 16, 2023