Lymphoblastic lymphoma (LBL) is a rare and aggressive lymphoblastic neoplasm, accounting for approximately 2% of non-Hodgkin lymphoma cases. Despite sharing clinical and morphological similarities with acute lymphoblastic leukemia (ALL), LBL is characterized by distinct genetic abnormalities. Due to the ambiguity surrounding treatments, the prognosis for LBL remains poor, with complete remission rates between 40-58% and 5-year disease-free survival rates between 36-70%. We present a case of a 42-year-old man diagnosed with B-acute lymphoblastic leukemia (B-ALL)/lymphoblastic lymphoma (LBL). The diagnosis was challenging due to the rarity of the condition and the overlapping features of LBL and ALL. This case report highlights the predominance of lymphoblasts and the presence of the p190 (e1a2) BCR::ABL1 transcript, which is frequently associated with poor prognostic outcomes in lymphoblastic malignancies. The coexistence of both B-ALL and LBL underscores the necessity of a comprehensive understanding of the diagnostic approach, which is essential for optimizing treatment strategies and improving prognosis.