Thyroid Nodule in an Eighteen-Year-Old Man as the First Presentation of Acute Lymphoblastic Leukemia

INTRODUCTION: Acute lymphoblastic leukemia (ALL) is the most common malignancy of childhood. Patients with ALL commonly present with easy bruising and infections due to medullary involvement. The extra medullary involvements of ALL manifests as hepatosplenomegaly, lymphadenopathy, and testicular enlargement. Among extramedullary manifestations of the ALL, thyroid involvement is rare. Herein, we reported a case of ALL that manifested as a thyroid nodule. CASE PRESENTATION: An 18-year-old young man with a thyroid nodule presented without any other symptom or sign. The excisional biopsy of the nodule was planned by the surgeon. After two months of lost to follow-up, the patient returned with a complaint of continuous bleeding after a tooth extraction. Peripheral blood smear (PBS) study and bone marrow aspiration proposed ALL and the flow cytometry confirmed the diagnosis. The R-Hyper-CVAD induction chemotherapeutic regimen (rituximab in combination with cyclophosphamide, vincristine, doxorubicin, and dexamethasone) was used for treatment. Interestingly, thyroid sonography and Tc(99m) scan showed resolution of the thyroid nodule after chemotherapy. DISCUSSION: In this patient, poor interdisciplinary communication and the rarity of this manifestation led to a delayed diagnosis. Therefore, we insist on more careful clinical examinations, reassessment of unusual FNA reports, and closer communication between clinicians and pathologists in such cases. This approach would lead to accurate and earlier diagnosis and would prevent unnecessary interventions.