Granulocytic sarcoma as an initial manifestation of acute promyelocytic leukemia: A case report with literature review

Rationale:Granulocytic sarcoma (GS) is a rare tumor consisting of myeloid blasts with or without maturation and occurs in sites other than the bone marrow. Due to its low prevalence, clinical cases and pathogenesis need to be studied. Therefore, we present a rare case of humerus GS occurring simultaneously with acute promyelocytic leukemia (APL) and studied a retrospective analysis of clinical characteristics and related treatment strategies, hoping that it could help to standardize the early diagnosis and treatment of APL/GS.Patient concerns:We present a case of humerus GS complicated with APL in a 22-year-old woman who experienced pain in right clavicle and shoulder for 6 months without any cause. While the aggravated pain were persistent for 2 months, causing limited movement of her right upper arm.Diagnoses:The presence of tumor in her right proximal humerus and end of clavicle was revealed by positron emission tomography-computed tomography. Subsequently, the mass collected during the operation was confirmed to be GS by the pathological immunohistochemical examination. Further progression to APL was based on marrow smears, flow cytometry, fluorescence in situ hybridization, and PML/RAR alpha gene detection.Interventions and outcomes:The patient underwent the tumorectomy, and then received 28-day induction therapy with all-trans retinoic acid (ATRA) (25 mg/m2/d) and arsenic trioxide. The posttreatment bone marrow smear and flow cytometry showed that she was in a complete remission. Consolidation treatment was performed with ATRA 25 mg/m2 PO BID for 2 weeks every 4 weeks and arsenic trioxide 0.16 mg/kg IV 5 days a week for 4 weeks every 8 weeks for a total of 6 cycles. Currently, the patient was routinely followed-up at an outpatient clinic, and has been maintained complete remission for 15 months.Lessons:We present an uncommon case of a humeral APL/GS, and conducted a comprehensive analysis of 28 cases of APL/GS. Despite the rarity of APL/GS, it should be diagnosed at an early stage. Furthermore, ATRA are recommended in the treatment plan of APL/GS.