Background: The diagnosis of early Mycosis Fungoides (MF) is quite challenging because of its overlapping clinicopathologic findings with various reactive dermatoses. A comprehensive assessment of clinical history is absolutely essential as pathologic criteria alone are insufficient. Aim: We aimed to diagnose early MF seeking an algorithm proposed by the International Society for Cutaneous Lymphoma (ISCL), define various significant diagnostic criteria and describe the associated clinical and histological mimics. Materials and Methods : Formalin fixed, paraffin embedded and H&E stained sections of forty skin biopsies from thirty nine clinically suspected early MF patients (n = 39) were studied initially. Various clinical and histopathological parameters were recorded followed by immunohistochemistry (IHC) with selected markers to arrive at a proper diagnosis. Results: Early MF was diagnosed in 9 patients (23.1%), parapsoriasis in 5 patients (12.8%), psoriasiform dermatitis in 7 patients (17.9%) and spongiotic dermatitis in 5 patients (12.8%). Remaining 13 patients (33.3%) were grouped under miscellaneous category comprising of other reactive dermatoses. Atypical lymphocytes were seen in 8 patients with early MF (n = 9) and 2 patients with parapsoriasis (n = 5). No statistical significance was observed between the two groups (P > 0.05, Fisher’s exact test). Conclusions: Some patients with early MF fail to show the typical histological features of the disease. In such instances, multiple biopsies from different lesions are highly useful and the algorithm developed by ISCL is a valid tool in diagnosis. Epidermotropism is considered as histological hallmark. IHC is not needed in all cases, particularly when the clinical and histopathological features are quite obvious.

Keywords: Algorithm; Early MF; Epidermotropism; ISCL; Reactive Dermatoses.