title: Two cases of histiocytic sarcoma with BCL2 translocations and occult or subsequent follicular lymphoma.
abstract: Histiocytic sarcoma is rare and difficult to distinguish from histologic mimics such as myeloid sarcoma due to its relatively nonspecific immunoprofile. A subset of histiocytic sarcomas are clonally related to synchronous or metachronous follicular lymphomas. Interestingly, the histiocytic tumor component has been shown to harbor BCL2 gene translocations that are identical to those found in the lymphoma. We present one case of histiocytic sarcoma and initially occult follicular lymphoma in which detection of a BCL2 gene translocation helped support the diagnosis. We also provide follow-up regarding a previously published case of histiocytic sarcoma with IGH/BCL2 fusion gene in which the patient subsequently developed follicular lymphoma and, later, diffuse large B-cell lymphoma. Our findings suggest that BCL2 gene translocations are a recurrent feature of a distinct subset of histiocytic sarcomas that are associated with follicular lymphoma; the follicular lymphoma component may be clinically occult at the time of diagnosis. Testing for an IGH/BCL2 translocation should be considered in the diagnostic workup of difficult-to-characterize neoplasms with histiocytic/monocytic morphology and immunoprofile.
authors.affiliation: Department of Pathology, Stanford University, Stanford, CA, 94305, -5324. Electronic address: Sfernand@stanford.edu.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Fernandez-Pol
authors.affiliation: Department of Pathology, Stanford University, Stanford, CA, 94305, -5324. Electronic address: DBangs@stanfordhealthcare.org.
authors.forename: Charles D
authors.initials: CD
authors.lastname: Bangs
authors.affiliation: Department of Pathology, Stanford University, Stanford, CA, 94305, -5324. Electronic address: ACherry@stanfordhealthcare.org.
authors.forename: Athena
authors.initials: A
authors.lastname: Cherry
authors.affiliation: Department of Pathology, Stanford University, Stanford, CA, 94305, -5324. Electronic address: DArber@stanfordhealthcare.org.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Arber
authors.affiliation: Department of Pathology, Stanford University, Stanford, CA, 94305, -5324. Electronic address: ditag@stanford.edu.
authors.forename: Dita
authors.initials: D
authors.lastname: Gratzinger
mesh_terms: D000368:Aged; D014408:Biomarkers, Tumor / Q000235:genetics*; D001706:Biopsy; D001856:Bone Marrow Examination; D019046:Bone Marrow Neoplasms / Q000737:chemistry / Q000235:genetics* / Q000473:pathology / Q000628:therapy; D005260:Female; D050939:Gene Fusion; D050438:Genes, Immunoglobulin Heavy Chain; D020022:Genetic Predisposition to Disease; D054747:Histiocytic Sarcoma / Q000235:genetics* / Q000473:pathology / Q000628:therapy; D006801:Humans; D007150:Immunohistochemistry; D017404:In Situ Hybridization, Fluorescence; D008113:Liver Neoplasms / Q000737:chemistry / Q000235:genetics* / Q000473:pathology / Q000628:therapy; D008224:Lymphoma, Follicular / Q000737:chemistry / Q000235:genetics* / Q000473:pathology / Q000628:therapy; D016403:Lymphoma, Large B-Cell, Diffuse / Q000737:chemistry / Q000235:genetics / Q000473:pathology / Q000628:therapy; D008297:Male; D008875:Middle Aged; D019042:Muscle Neoplasms / Q000737:chemistry / Q000235:genetics* / Q000473:pathology / Q000628:therapy; D010641:Phenotype; D011379:Prognosis; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics*; D013997:Time Factors; D014178:Translocation, Genetic
chemical_list: C000595707:BCL2 protein, human; D014408:Biomarkers, Tumor; D019253:Proto-Oncogene Proteins c-bcl-2
keywords: BCL2; Follicular lymphoma; Histiocytic sarcoma; Monocytic differentiation; Myeloid sarcoma