MYCOSIS FUNGOIDES 
The biopsy taken 9 years ago demonstrates a superficial lymphocytic infiltrate that is not angiocentric, and this is associated with fibrosis of the papillary dermis. This combination raises the possibility of mycosis fungoides or a mycosis fungoides precursor. The presence of lymphocyte atypia manifested by dark staining nuclei that are sometimes oriented eccentrically within amphophilic cytoplasm makes the diagnosis of mycosis fungoides almost a certainty. Lymphomatoid papulosis can also look like this, however. The clinical presentation is very useful in making this distinction: lymphomatoid papulosis usually resembles pityriasis lichenoides et varioloformis acuta whereas mycosis fungoides is characterized in the early stages by patches and plaques. Another biopsy, that is not illustrated, that was taken at the same time, demonstrated a lichenoid reaction with transepidermal keratinocyte enlargement and Civatte body production plus the atypical lymphocytes.
One of the current biopsies demonstrates a lichenoid reaction associated with the atypical lymphocytic infiltrate.   Therefore, mycosis fungoides enters the differential diagnosis of the lichenoid reaction. This patient has involvement of over 50% of his body, and there is skin tumor formation.

 
Biopsy taken 9 years ago showing an atypical lymphocytic infiltrate that is not angiocentric, and the infiltrate is associated with fibrosis of the papillary dermis. Clinical information was not furnished with the biopsy, so it was signed out as 'mycosis fungoides versus lymphomatoid papulosis'.
Recent biopsy showing a lichenoid reaction on the left with lymphocytic  exocytosis on the right. No significant spongiosis associated with the exocytosis (another feature of mycosis fungoides).
Higher power view of the lichenoid reaction with arrow pointing to a Civatte body. Note transepidermal kertinocyte enlargement characteristic of lichenoid reaction.
Very high power view of some of the atypical lymphocytes.These are the cell having opaque nuclei that are occasionally associated with basophilic or amphophilic cytoplasm.

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