Patch-stage Mycosis fungoides with an unusual clinical appearance simulating digitate parapsoriasis

The patient is a 70 year old male who has a history of small plaque parapsoriasis involving the upper arm, the abdomen, and the upper back.

The biopsy shows a significantly atypical epidermotropic lymphocytic infiltrate. Many of the lymphocytes have a severely atypical cerebriform appearance. It is phenotypically very abnormal given the markedly skewed intraepidermal CD4 to CD8 ratio and the extent of loss of CD7.

In small plaque digitate parapsoriasis, the cases typically do not have any lymphoid atypia. Biopsies characteristically show a sparse lymphocytic infiltrate with spongiosis and parakeratosis.

Click images to begin the slideshow

Slide 1: The shave sample shows a superficial lymphocytic infiltrate that is both interstitial and perivascular. There are foci of infiltration of the epidermis by lymphocytes.

Slide 2: The shave sample shows a superficial lymphocytic infiltrate that is both interstitial and perivascular. There are foci of infiltration of the epidermis by lymphocytes.

Slide 3: The lymphocytes in the epidermis and dermis appear similar. They are small to intermediate in size manifesting nuclear contour irregularity.

Slide 4: The majority of the lymphocytes exhibit an atypical cerebriform appearance. The full extent of lymphoid atypia is best appreciated under oil.

Slide 5: There is highlighting of the lymphocytes in the epidermis and dermis for the pan T-cell marker CD3 and CD5 (pictured here).

Slide 6: There is a significant decrement in staining for the pan T-cell marker CD7 with the estimated reduction is likely in the 80% realm.

Slide 7: There is clearly a predominance of CD4 T-cells (pictured here) over those of the CD8 subset in the dermis, whereby the ratio is greater than 4:1 but less than 10:1.

Slide 8: There is clearly a predominance of CD4 T-cells over those of the CD8 subset (pictured here) in the dermis, whereby the ratio is greater than 4:1 but less than 10:1.

Slide 9: The CD30 preparation is essentially negative.