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Granular acute lymphoblastic leukemia: a case report and literature review
1Division of Pathology, City of Hope National Medical Center, Duarte, California 91010, USA.
Insights
A rare granular acute lymphoblastic leukemia (ALL) case in an adult highlights diagnostic challenges. Granular ALL, common in children, mimics myeloid leukemia in adults, necessitating careful immunophenotyping to avoid misdiagnosis.
Area of Science:
- Hematology
- Oncology
- Pathology
Background:
- Granular acute lymphoblastic leukemia (ALL) is a rare subtype characterized by cytoplasmic granules in lymphoblasts.
- While more common in pediatric populations (2-7%), it is exceptionally rare in adults.
- Distinguishing granular ALL from myeloid differentiation is crucial to prevent misdiagnosis.
Observation:
- A 45-year-old woman with a history of multiple myeloma presented with lymphoblasts exhibiting prominent cytoplasmic granules.
- Cytochemical staining revealed positivity for acid phosphatase and Periodic Acid-Schiff, but negativity for myeloperoxidase.
- Immunophenotype analysis confirmed a precursor B-cell phenotype.
Findings:
- The patient's granular lymphoblasts mimicked myeloblasts, posing a diagnostic challenge.
- Despite granular morphology, immunophenotyping confirmed the B-cell lineage, ruling out acute myeloid leukemia.
- This case underscores the rarity and diagnostic complexities of granular ALL in adults.
Implications:
- Accurate differentiation of granular ALL from acute myeloid leukemia is critical, especially in adults.
- Immunophenotyping is essential for correct diagnosis and appropriate treatment strategies.
- Reviewing adult granular ALL cases aids in understanding this rare entity and refining diagnostic criteria.
Abstract:
Authors report a rare case of granular acute lymphoblastic leukemia (ALL) in a 45-year-old woman with a history of multiple myeloma. The patient's lymphoblasts contained large numbers of distinctive cytoplasmic granules closely mimicking heavily granulated myeloblasts in acute myeloid leukemia. These blasts were completely negative for myeloperoxidase but positive for acid phosphatase and Periodic Acid-Schiff reaction by cytochemical staining. Immunophenotype analysis by immunohistochemistry clearly demonstrated precursor B-cell phenotype. Granular ALL occurs approximately 2 to 7% in childhood populations but is extremely rare in adults. Such cases may cause problematic distinction from myeloid differentiation and lead to misdiagnosis of acute myeloid leukemia. Ten cases of adult granular acute lymphoblastic leukemia described to date in the literature were also reviewed.