Original ArticlesPlasmacytoid Dendritic Cell Dermatosis Associated to Myeloproliferative/Myelodysplastic NeoplasmsMachan, Salma MD, PhD*; Alonso-Dominguez, Juan M. MD, PhD†; Sánchez García, F. Javier MD‡; Nieves Salgado, Rocío MD, PhD†; Soto, Carlos MD†; Castro, Yolanda MD§; Pajares, Raquel Tech§; Manso, Rebeca PhD§; Santonja, Carlos MD, PhD§; Serrano del Castillo, Cristina MD, PhD†; Piris, Miguel A. MD, PhD‡; Requena, Luis MD, PhD*; Rodríguez Pinilla, Socorro M. MD, PhD‡ Author Information *Dermatology Department †Haematology Department ‡Pathology Department, FJD §Pathology Department, Hospital Universitario Príncipe de Asturias, Alcalá de Henares, Madrid, Spain The Comité de Ética de la Investigación de la Fundación Jiménez Díaz, CEIm-FJD approved the study “Linfomas agresivos, análisis clínico y genómico para una medicina de precisión (B2017/BMD-3778. LINFOMAS CM. CI: PIC75-018)” in which this study is included. S.M. and J.M.A.-D. contributed equally to this paper. This work was supported by grants from the Instituto de Salud Carlos III (ISCIII) of the Spanish Ministry of Economy and Competence (MINECO, RTICC ISCIII and CIBERONC) (SAF2013-47416-R, RD06/0020/0107-RD012/0036/0060 and Plan Nacional I+D+I: PI17/2172, PI16/01294 and PIE15/0081), AECC and the Madrid Autonomous Community. Conflicts of Interest and Source of Funding: The authors have disclosed that they have no significant relationships with, or financial interest in, any commercial companies pertaining to this article. Correspondence: Socorro M. Rodríguez Pinilla, MD, PhD, Pathology Department, Instituto Investigación Sanitaria Fundación Jiménez Díaz, Avda Reyes Católicos, 2, Madrid E-28040, Spain (e-mail: [email protected]). Supplemental Digital Content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's website, www.ajsp.com. The American Journal of Surgical Pathology: December 2022 - Volume 46 - Issue 12 - p 1623-1632 doi: 10.1097/PAS.0000000000001960 Buy SDC Metrics Abstract Cutaneous lesions in the setting of myeloproliferative neoplasms and myelodysplastic syndromes are poorly understood. We report 6 patients with pruritic papular eruptions composed of mature T-lymphocytes with large clusters of CD123-positive cells. Double immunohistochemical studies demonstrated a lack of myeloid cell nuclear differentiation antigen in the CD123-positive cells, which expressed SPIB, confirming that they were mature plasmacytoid dendritic cells. Four patients were diagnosed with chronic myelomonocytic leukemia and 2 with myelodysplastic syndromes (AREB-I and myelodysplastic syndromes with 5q deletion, respectively). All patients had a long history of hematological alterations, mainly thrombocytopenia, preceding the cutaneous disorder. Nevertheless, the skin lesions developed in all cases coincidentally with either progression or full-establishment of their hematological disease. Most cutaneous lesions disappeared spontaneously or after corticosteroid treatment. Molecular studies performed in both bone marrow and cutaneous lesions in 2 patients demonstrated the same mutational profile, confirming the specific, neoplastic nature of these mature plasmacytoid dendritic cells-composed cutaneous lesions. Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.