Acute Lymphoblastic Leukemia in an Adolescent Girl with Graves’ Disease: A Coincidence or Consequence

Background: Graves’ disease (GD)-related bone marrow injury presents usually as agranulocytosis or less commonly as pancytopenia. However, acute lymphoblastic leukemia (ALL) has been reported recently in an adult patient with GD. The underlying pathogenesis is not fully understood. Nevertheless, the harmful effects of anti-thyroid drugs or autoimmune reaction to bone marrow cells are anticipated to be the causative factors. Case Presentation: We report a 16.5-year-old girl with GD who was on carbimazole for the first 14 months of her illness, with irregular follow-up; then it was withdrawn because she developed hypothyroidism. Meanwhile, she developed severe anemia without fever which necessitated blood transfusion. Eight months later, she presented with thyrotoxicosis relapse, febrile illness, bone pain, and pancytopenia which was proved to be ALL on bone marrow examination. Conclusion: The presence of ALL in a young GD patient is an unprecedented event. Although it is difficult to demonstrate the causality between them, need for further studies cannot be denied.