RESUMO
OBJECTIVE: Our objective was to describe the clinicopathologic and immunohistochemical features of acute lymphoblastic leukemia/lymphoma (ALL/LBL) of the oral and maxillofacial region (OMF). STUDY DESIGN: Cases diagnosed as ALL/LBL of the OMF region were retrieved from the files of 2 Brazilian and 1 Guatemalan oral pathology services from 2005 to 2017. Microscopic and immunohistochemical features of each case were reviewed and fully described, and clinical data were retrieved from the pathology reports. RESULTS: During the period considered, 6 cases were identified. Male patients were the most affected (4:2), with a mean age of 19 years old. The mandible was involved in 2 cases, the maxilla in 2, the cheek mucosa in 1, and the parotid gland in 1. Painful swelling was the most common presentation, and 3 patients also had systemic complaints. Microscopically, tumors revealed solid infiltrations of small to medium-sized immature cells. "Puzzle-like" and "starry-sky" patterns were observed, and "single lane" growth was also identified. Immunohistochemically, 2 cases were diagnosed as T-cell ALL/LBL with the leukocyte common antigen (LCA)+/cCD3+/CD79 a+focal/CD20-/PAX5-/CD99+/CD34-/CD10+/terminal deoxynucleotidyl transferase (TdT)+ phenotype and 4 as B-cell ALL/LBL with the LCA+/CD3-/CD20-/CD79 a+/CD10+/CD34 variable/TdT+ predominant phenotype. The Ki67 index ranged from 80% to 99%. CONCLUSION: OMF ALL/LBL is rare, but its microscopic features and immunohistochemical profiles CD3+or CD79 a+/CD10+/CD34+variable/CD99+/TdT+ contribute to the correct diagnosis.