title: When dead cells tell tales-cutaneous involvement by precursor T-cell acute lymphoblastic lymphoma with an uncommon phenotype.
abstract: The thymic type of precursor T-cell acute lymphoblastic lymphoma (pre-T ALL), an uncommon T-cell malignancy, typically presents as a thymic mass and expresses terminal deoxonucleotidyl transferase, CD7, and cytoplasmic CD3, with variable expression of other markers. Cutaneous presentation in pre-T ALL is highly unusual. We describe a case of pre-T ALL presenting as 2 papulonodular lesions on the face of an otherwise asymptomatic 27-year-old man. Microscopic examination of both lesions revealed a moderate to dense pandermal infiltrate of medium-sized lymphocytes with extensive "crush" artifact, whereas immunohistochemistry revealed positive staining of lesional cells for CD45, CD3, Bcl-2, Ki-67, CD5, CD7, and CD34 but negative staining for CD4, CD8, CD30, CD56, CD10, CD117, anaplastic lymphoma kinase protein, TdT, myeloperoxidase, CD79a, and CD20. Gene rearrangement studies performed on both biopsies identified a clonal population of T lymphocytes. A subsequent computed tomography scan revealed a 9-cm mediastinal mass encasing all major mediastinal vessels, whereas a bone marrow biopsy revealed blasts with an immunophenotype similar to that of the cutaneous lesions. Features unique to this case include the cutaneous presentation and the immunophenotype-absence of CD4, CD8, and TdT with expression of CD34-both highly unusual features for pre-T ALL.
authors.affiliation: Department of Dermatology, Boston University School of Medicine, MA, USA.
authors.forename: Ron
authors.initials: R
authors.lastname: Yaar
authors.forename: Karen
authors.initials: K
authors.lastname: Rothman
authors.forename: Meera
authors.initials: M
authors.lastname: Mahalingam
mesh_terms: D000328:Adult; D018952:Antigens, CD34 / Q000378:metabolism; D019011:Antigens, CD7 / Q000378:metabolism; D001706:Biopsy; D017252:CD3 Complex / Q000378:metabolism; D005145:Face; D006801:Humans; D008297:Male; D009336:Necrosis; D010641:Phenotype; D011230:Precancerous Conditions / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology*; D054218:Precursor T-Cell Lymphoblastic Leukemia-Lymphoma / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology*; D012867:Skin / Q000378:metabolism / Q000473:pathology*; D012878:Skin Neoplasms / Q000175:diagnosis / Q000378:metabolism / Q000473:pathology*
chemical_list: D018952:Antigens, CD34; D019011:Antigens, CD7; D017252:CD3 Complex