title: "Tear drops" in the cerebrospinal fluid: Correct by scatter, but pathognomonic by site.
abstract: Extramedullary relapse in acute promyelocytic leukemia (APL) is rare, but occurs most commonly in central nervous system (CNS), generally in high-risk cases (total leucocyte count≥10,000/µL, atypical morphology or disseminated intravascular coagulation at presentation), and concomitant with bone marrow (BM) relapse. Here, we describe a case of APL who except for CD56 positivity was low risk but had a CNS relapse without concomitant BM involvement. Diagnosis of isolated CNS relapse was based on characteristic tear-drop pattern for CD45/side scatter plot on flow cytometry, a full compatible immunophenotype and cytomorphology in the cerebrospinal fluid. The case illustrates the value of the latter and the importance of including CD56 in risk assessment of APL.
authors.affiliation: Laboratory Oncology Unit, Dr. BRAIRCH, All India Institute of Medical Sciences, Ansari Nagar, New Delhi-, 110029, India.
authors.forename: Reena
authors.initials: R
authors.lastname: Mittal
authors.forename: Anita
authors.initials: A
authors.lastname: Chopra
authors.forename: Sushant
authors.initials: S
authors.lastname: Soni
authors.forename: Sameer
authors.initials: S
authors.lastname: Bakhshi
authors.forename: Rajive
authors.initials: R
authors.lastname: Kumar
mesh_terms: D000293:Adolescent; D014408:Biomarkers, Tumor / Q000276:immunology*; D001853:Bone Marrow / Q000276:immunology / Q000473:pathology; D002490:Central Nervous System / Q000276:immunology* / Q000473:pathology; D004211:Disseminated Intravascular Coagulation / Q000134:cerebrospinal fluid / Q000175:diagnosis* / Q000276:immunology / Q000473:pathology; D017809:Fatal Outcome; D005434:Flow Cytometry; D042381:Granulocyte Precursor Cells / Q000276:immunology* / Q000473:pathology; D006801:Humans; D016130:Immunophenotyping; D015473:Leukemia, Promyelocytic, Acute / Q000134:cerebrospinal fluid / Q000175:diagnosis* / Q000276:immunology / Q000473:pathology; D017493:Leukocyte Common Antigens / Q000276:immunology*; D008297:Male; D012008:Recurrence
chemical_list: D014408:Biomarkers, Tumor; D017493:Leukocyte Common Antigens; C516769:PTPRC protein, human
keywords: APL; flow cytometry; isolated CNS relapse; tear drop