Abstract
T-cell acute lymphoblastic leukemia/lymphoma (T-ALL) is characterized by the combination of T-cell lineage and the presence of immaturity marker(s). Sometimes, the most common immaturity markers for initial flow cytometry screening in T-ALL may be negative, which can be a diagnostic pitfall. When a lack of common first-line immaturity markers is encountered in combination with gamma/delta T-cell receptor expression, a misdiagnosis of mature gamma-delta T-cell leukemia/lymphoma could be rendered. Here, we discuss two T-ALL cases with the absence of common flow cytometry immaturity markers and positive gamma/delta receptor expression.