SAT-353 Graves' Disease with Benign Ethnic Neutropenia: A Rare Association

Abstract Disclosure: S. Azmat: None. O. Lodhi: None. S. Rabbani: None. V. Trendafilova: None. Background: Benign ethnic neutropenia is chronic neutropenia characterized by an absolute neutrophil count less than 1500/ μL without having an increased risk of infections. It is suspected when all secondary causes of neutropenia have been ruled out and is commonly seen in people of African and Caribbean descent. Per the literature review, there are few reported cases of autoimmune diseases like SLE and RA seen with BEN. However, its coexistence with autoimmune thyroid disease, Grave's disease hasn't been much documented. This case reports a rare occurrence of Grave's disease with BEN and highlights unique diagnostic and management challenges. Clinical Case: A 19-year-old male with no significant past medical history was incidentally noted to have neutropenia on routine bloodwork, with an ANC level below the normal range but above 0.5 x 10⁹/L, Hb 14.9 g/dL(13.5-18 g/dL), platelets 222 x 10⁹/L(150-450 x 10⁹/L), Vitamin B12 313 pg/mL (160-950 pg/mL), folate 17.39 ng/mL( 2.5-20 ng/mL) and normal liver function tests. Peripheral smear showed leukopenia with a normal differential, with no blast cells. A year later bone marrow biopsy was done consistent with hypocellular bone marrow with trilineage hematopoiesis, with no dysplastic cells or blasts, and normal cytogenetics, consistent with diagnosis of benign ethnic neutropenia or autoimmune neutropenia. He had the lowest ANC of 0.4 x 10⁹/L at that time. Pt also started experiencing palpitations, and heat intolerance with significant weight loss. His labs were consistent with Graves' disease; TSH (<0.005 μIU/mL)( 0.27-4.2 uIU/mL)and elevated free T3 (9.04 pg/mL) (2.00-4.40 pg/mL)and free T4 (5.78 ng/dL)(0.58 -1.64). The patient was started on methimazole therapy, subsequent follow-ups showed improved thyroid function tests and the resolution of hyperthyroid symptoms. After three years of treatment with methimazole, the patient was transitioned to radioactive iodine therapy as he no longer wanted to take oral medications. Despite persistent neutropenia, the patient remained asymptomatic, with no major infections. The patient was counseled on infection prevention and signs of neutropenia-related complications. No active interventions for neutropenia are currently warranted given the absence of severe infections or other complications. The patient continued to follow up with endocrinology for the management of Graves' disease and hematology for monitoring of neutropenia. Conclusion: This case shows the coexistence of Graves’ disease and benign ethnic neutropenia (BEN) and thus emphasizes the importance of distinguishing BEN from other etiologies of chronic neutropenia on clinical and laboratory findings. This case also highlights the fact that BEN has a good outcome with thioamides antithyroid agent, in the absence of severe infections. More research is needed to assess the long-term clinical significance of this association. Presentation: Saturday, July 12, 2025