AML-034 Granulocytic Sarcoma Disguised as Lymphoblastic Lymphoma.

CONTEXT: Acute myeloid leukemia (AML) is a malignant clonal disease of hematopoietic stem cells affecting the blood and bone marrow. Granulocytic sarcoma (chloroma) is a rare disease characterized by an extramedullary myeloid cell mass with or without bone marrow infiltration.

OBJECTIVE: We report a case of AML presented with granulocytic sarcoma causing cord compression.

PATIENTS: An 18-year-old male presented in January 2022 with acute onset and progressive low backache and lower limb weakness with no history of associated trauma. The condition was followed one week later by urine and stool incontinence.

INTERVENTIONS: Clinical examination revealed motor and sensory impairment with bladder and bowel dysfunction. Pan CT scan showed an anterior mediastinal amalgamated lymph node with central necrosis and heterogeneous enhancement measuring 3.5×6 cm. MRI study detected a dorso-lumbar intradural extramedullary lesion 5×8×6 cm and a heterogeneously enhancing pre-sacral soft tissue mass measuring 3.2×7×6 cm.

MAIN OUTCOME MEASURES: Biopsy and pathological examination of the dorsal mass showed infiltration by sheets and aggregates of malignant round cell tumor with diffuse, positive reaction of the tumor cells by LCA, CD99, PAX5, and BCL2 and 80%-90% of the cells positively stained by Ki-67, a picture suggestive of B-cell lymphoblastic lymphoma. A complete blood count revealed the following: white blood cell count 6.5×109 /l, absolute neutrophil count 2.4×109 /l, hemoglobin 11.9 g/dl, mean corpuscular volume 88.6 fl, platelets 217×109 /l. Along with further immunohistochemical assessment of the dorsal lumbar mass, bone marrow examination showed 70% of blast cells positively stained for MPO, CD117, CD33, CD34, HLADR, and CD58 and negatively stained for TdT, CD79, cCD3, CD22, CD19, CD10, and CD20 with further immune staining of the spinal mass. The picture was consistent with AML.

RESULTS: Treatment commenced, and the patient achieved complete remission following 2 induction therapies with a "7+3" regimen. On the clinical level, the patient showed noticeable improvement in sensation and motor power and was under high-dose cytarabine while the article was written.

CONCLUSIONS: Myeloid sarcoma is a rare tumor consisting of immature granulocytic cells and is frequently misdiagnosed particularly in the absence of clinical suspicion of myeloid malignancies. Competent diagnostic clinical, laboratory, and radiological imaging of granulocytic sarcoma are crucial for proper management.