As the name implies, epidermotropism refers to the phenomenon of lymphocytes residing in the epidermis. This is in contrast to exocytosis, in which lymphocytes move out through the epidermis. Exocytosis is associated with spongiosis while epidermotropism is associated with clear halos around individual lymphocytes and generally lacks spongiosis. While exocytosis and spongiosis are characteristic features of inflammatory disorders, such as eczematous dermatitis, epidermotropism is characteristic of mycosis fungoides (MF) , the most common type of cutaneous T-cell lymphoma (CTCL).

The disorders are
All these disorders may have significant epidermotropism and be misdiagnosed as mycosis fungoides.

The answer is no. In early lesions of mycosis fungoides, the intraepidermal lymphocytes may be so few that they may be overlooked. Sometimes spongiosis accompanies epidermotropism and may overshadow it, resulting in making the wrong diagnosis of spongiotic dermatitis. This is especially true when the clinical presentation of mycosis fungoides is eczematous, and the clinician has not suspected the diagnosis in order to put it on the requisition form. The author has seen several such cases managed for a long time as eczematous dermatitis.