Mycosis Fungoides: Histopathology and T Cell Receptor Gene Rearrangements in Indian Patients

Abstract

Introduction: Mycosis fungoides (MF) is the commonest cutaneous T cell lymphoma. MF presents in three stages the patch, plaque, and tumor. The distinction of patch-stage MF from inflammatory dermatoses is a diagnostic challenge. Need for the Study: MF shows T cell receptor gamma and beta gene rearrangements (TCRG and TCRB), detectable by polymerase chain reaction (PCR). Data about the clonality of infiltrates in our population and their utility in diagnosis is lacking. Materials and Methods: Skin biopsies from 50 patients with mycosis fungoides from January 2007 to July 2015 were studied for microscopic features. TCR gamma and beta gene rearrangement assays were performed on 14 patients where formalin fixed paraffin embedded (FFPE) was available. DNA was extracted using the phenol-chloroform method. PCR was performed using primers from Invivoscribe Identiclone assay. Clonality was analyzed using Agarose gel electrophoresis. Results: Of the 50 cases, 37 were patch, nine were plaque, and four were tumor stage. All cases showed disproportionate lymphocyte epidermotropism, 38 showed lymphocyte atypia, and 33 showed adnexotropism (11 eccrotropism and 22 folliculotropism). Clonality was assessed in 14 cases. Of these, 3/9 patch stages were monoclonal (1/3 monoclonal for beta, and 2/3 monoclonal for gamma and beta). 3/3 plaque stage MF was monoclonal (1/3 for gamma, 2/3 for both), and 1/2 tumor stage MF was monoclonal for gamma and beta receptors. Conclusion: The patch stage was the most common presentation. TCR gene rearrangements were noted in 50% of MF, with TCR gamma rearrangements being more common. Plaque and tumor stages yielded higher positive rates.

Keywords

• mf
• tcr gene rearrangements
• histopathology