Clinicopathological Spectrum of Cutaneous Lymphomas and Distinction of Early Mycosis Fungoides from its Mimics—A Retro-Prospective Descriptive Study from Southern India

BACKGROUND: Cutaneous lymphomas (CLs) could be either primary (PCL) or secondary; the former comprises cutaneous T-cell lymphomas (CTCLs) and cutaneous B-cell lymphomas (CBCLs). Mycosis fungoides (MF) is the most common PCL. Diagnosis of early MF and distinguishing it from benign inflammatory mimics is challenging. This study aims to assess the clinicopathological spectrum of CL and to characterize early MF from its mimics using clinical characteristics, histopathological features, and ancillary techniques. MATERIALS AND METHODS: This retro-prospective descriptive study was conducted in a tertiary-care institute, for over 5 years. Clinically as well as histopathologically suspected and biopsy-proven CL and their mimics were included. Cases were reviewed and subgrouped based on clinical and histopathological parameters and immunohistochemistry (IHC). Data were analyzed using descriptive statistics and a Chi-square test at a 5% level of significance. RESULTS: Among PCL, CTCL comprised 84% (21/25) and CBCL was 16% (4/25); the most common CTCL was MF at 81% (17/21). Histologically, atypia of dermal infiltrate (100%), epidermotropism (91.7%), basal alignment of lymphocytes (91.7%), clear haloed cells (91.7%), wiry collagen (66.7%), grandiosity sign (50%), eccrine infiltration (66.7%), and follicular infiltration (50%) were significantly associated with early MF. Spongiosis (84.6%), pigment incontinence (84.6%), exocytosis (76.9%), and parakeratosis (76.9%) were significantly associated with inflammatory mimics. There was no significant difference in the downregulation pattern of CD7 (P = 0.206) between early MF and its mimics. The four cases of CBCL in our study were plasmablastic lymphoma, diffuse large B-cell lymphoma, follicular lymphoma, and lymphoblastic lymphoma. CONCLUSION: MF was the most common PCL. Histological parameters showed a significant difference, whereas IHC did not show any significant difference between early MF and its mimics.