pustular mycosis fungoides

MYCOSIS FUNGOIDES

The clinical history of this being part of a chronic dermatosis characterized by the presence of patches and plaques with erythematous and papulosquamous features, some of which have areas of sparing, combined with the pathology is diagnostic of mycosis fungoides.

A superficial band-like infiltrate of lymphocytes associated with abnormally coarse collagen fibers in the papillary dermis is found in most cases. Epidermotropism is variably prominent, and there is not the degree of spongiosis that would be expected in dermatitis having this much lymphocytic exocytosis. This lack of significant spongiosis associated with lymphocytic exocytosis is also seen in pityriasis lichenoides et varioliformis acuta, but the perivascular lymphocyte distribution and the presence of prominent holes in the epidermis are some of the distinguishing features of PLEVA. Often there is no evidence of interaction of the lymphocytes and keratinocytes, as in this case, but sometimes there is a lichenoid reaction.

Low power view showing a band-like infiltrate of lymphocytes associated with lymphocytic exocytosis and very little epidermal spongiosis.

High power of above. Polymorphonuclear leukocytes are in the stratum corneum, and these are very unusual in mycosis fungoides. The PAS stained sections did not reveal fungi. Bacterial origin cannot be excluded. There is a rare variant of mycosis fungoides that is described as being pustular.

Another high power view. Note the wavy collagen bundles that are a little thicker than normal for the papillary dermis.

Another high power view showing prominent lymphocytic exocytosis without spongiosis or keratinocyte hole formation. Also note the coarse collagen fibers in the papillary dermis.

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	Low power view showing a band-like infiltrate of lymphocytes associated with lymphocytic exocytosis and very little epidermal spongiosis.
	High power of above. Polymorphonuclear leukocytes are in the stratum corneum, and these are very unusual in mycosis fungoides. The PAS stained sections did not reveal fungi. Bacterial origin cannot be excluded. There is a rare variant of mycosis fungoides that is described as being pustular.
	Another high power view. Note the wavy collagen bundles that are a little thicker than normal for the papillary dermis.
	Another high power view showing prominent lymphocytic exocytosis without spongiosis or keratinocyte hole formation. Also note the coarse collagen fibers in the papillary dermis.