Diagnostic 2-Gene Classifier in Early-Stage Mycosis Fungoides: A Retrospective Multicenter Study

• Published in: Blood 2019-11, Vol.134 (Supplement_1), p.2772-2772
• Main Authors: Nielsen, Pia Rude, Eriksen, Jens Ole, Lindahl, Lise M., Wehkamp, Ulrike, Andersen, Gitte Rinds, Bzorek, Michael, Grønbæk, Kirsten, Odum, Niels, Litman, Thomas, Gjerdrum, Lise Mette Rahbek
• Format: Article
• Language: English
• ISSN: 0006-4971; 1528-0020
• DOI: 10.1182/blood-2019-122031

Introduction Mycosis fungoides (MF) is the most common type of cutaneous T-cell lymphoma and represents more than 50% of all primary cutaneous lymphomas. It is typically an indolent disorder with limited patches and plaques. One third, however, experience progression with ulcerating tumors and possible further systemic dissemination. Currently, the diagnosis of MF is based on clinical and histological examinations, but this has proven, especially in early-stage disease, to be challenging due to similarities with several benign skin conditions such as psoriasis, pityriasis lichenoides chronica, and dermatitis. Despite intensive research, reliable diagnostic biomarkers for early-stage MF are still needed. This study aims to identify a diagnostic classifier that could support the diagnostic workup leading to an exact diagnosis in the early-stage of this complex and potentially lethal disease. Methods We analyzed 43 formalin-fixed and paraffin-embedded (FFPE) skin biopsies from 36 patients with early-stage MF. Seven patients had 2 longitudinal biopsies available for analysis. These were compared with FFPE skin biopsies from patients with unspecified dermatitis (n=29) and healthy skin (n=12). All samples were collected from the archives of the Department of Pathology, Region Zealand, Denmark in the period 1990-2016. The histological samples were revised and clinical records were reviewed to establish the diagnosis and stage for each patient. Total RNA was extracted from ten 10-μm sections of FFPE tissue, and 50-100 ng of RNA was analyzed on the NanoString nCounter platform by applying the Myeloid Innate Immunity Panel, which quantifies the expression of 800 immune related genes. Differentially expressed genes (DEG, 2-fold change, p