title: Tumor-forming plasmacytoid dendritic cells associated with myeloid neoplasms. Report of a peculiar case with histopathologic features masquerading as lupus erythematosus.
abstract: Plasmacytoid dendritic cells (PDC) belong to a subtype of dendritic cells that are normally absent in healthy skin. In some inflammatory diseases of the skin, especially lupus erythematosus (LE), these cells are occasionally recruited in great amounts, which can be used as a helpful clue for diagnosis. Rarely, PDC may also accumulate in the skin of patients with myeloid leukemia, a yet poorly known condition currently called 'tumor-forming PDC associated with myeloid neoplasms'. In this study, we describe a patient with unsuspected chronic myelomonocytic leukemia who developed cutaneous lesions characterized by a dermal infiltrate rich in PDC. Similarly to LE, such neoplastic PDC were accompanied by interface dermatitis-like changes, but displayed an aberrant phenotype and shared the same chromosomal abnormality with the leukemic cells identified in the bone marrow, thus revealing the neoplastic nature of the process. This observation illustrates that tumor-forming PDC associated with myeloid neoplasms may microscopically mimic LE in some patients. Accordingly, a hematologic workup is recommended in any skin lesion featuring excessive numbers of PDC, even if morphological alterations suggestive of interface dermatitis are found.
authors.affiliation: Pathology, Institut de Pathologie et de Génétique (IPG), Gosselies, Belgium.
authors.forename: Jean-Louis
authors.initials: JL
authors.lastname: Dargent
authors.affiliation: Department of Dermatology, Grand Hôpital de Charleroi (GHDC), Loverval, Belgium.
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Henne
authors.affiliation: Department of Oncology, Grand Hôpital de Charleroi (GHDC), Charleroi, Belgium.
authors.forename: Delphine
authors.initials: D
authors.lastname: Pranger
authors.affiliation: Department of Molecular and Translational Medicine, Section of Pathology, School of Medicine, University of Brescia, Brescia, Italy.
authors.forename: Piera
authors.initials: P
authors.lastname: Balzarini
authors.affiliation: Pathology, Institut de Pathologie et de Génétique (IPG), Gosselies, Belgium.
authors.forename: Daniel
authors.initials: D
authors.lastname: Sartenaer
authors.affiliation: Laboratory of Clinical Biology, Grand Hôpital de Charleroi (GHDC), Charleroi, Belgium.
authors.forename: Geneviève
authors.initials: G
authors.lastname: Bulliard
authors.affiliation: Pathology, Institut de Pathologie et de Génétique (IPG), Gosselies, Belgium.
authors.forename: Katrina
authors.initials: K
authors.lastname: Rack
authors.affiliation: Department of Molecular and Translational Medicine, Section of Pathology, School of Medicine, University of Brescia, Brescia, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Facchetti
mesh_terms: D003713:Dendritic Cells / Q000378:metabolism / Q000473:pathology; D020405:Dermis / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007951:Leukemia, Myeloid / Q000378:metabolism / Q000473:pathology; D008178:Lupus Erythematosus, Cutaneous / Q000378:metabolism / Q000473:pathology; D008297:Male; D008875:Middle Aged; D010950:Plasma Cells / Q000378:metabolism / Q000473:pathology; D012878:Skin Neoplasms / Q000378:metabolism / Q000473:pathology
keywords: chronic myelomonocytic leukemia; lupus erythematosus; plasmacytoid dendritic cells