Ultraviolet radiation induces changes in membrane metabolism of human keratinocytes in culture.

Human keratinocytes in culture were prelabeled with [3H]arachidonic acid (AA) and then exposed to ultraviolet B radiation. Irradiated cells released labeled AA metabolites into media in a dose-dependent manner when compared to sham-irradiated cells. The response began immediately and continued for 24 h. Extracts from media were examined by high-performance liquid chromatography for identification of specific AA metabolites. Irradiated cells were stimulated to produce prostaglandin-like material (PGE2 and PGF2 alpha). These findings support the concept that the cell membrane of keratinocytes participates directly or indirectly in initiating the sunburn response. It is also felt that the metabolites formed following injury to the membrane are an integral component in the mediation of that response.

Acute myelomonocytic leukemia presenting as a benign-appearing cutaneous eruption.

Aleukemic leukemia cutis is a rare condition in which patients have skin lesions containing leukemic cells before evidence of leukemia can be detected in the peripheral blood. There are only 23 cases of this phenomenon documented in the English literature. We describe a 62-year-old woman who developed a diffuse, clinically benign-appearing cutaneous eruption, which histologically showed an atypical infiltrate of cells, 4 months before leukemic cells were found in her peripheral blood and the diagnosis of acute myelomonocytic leukemia was made by bone marrow aspiration. This case illustrates the difficulty in diagnosing leukemia cutis from examination of routine histologic sections and the importance of specialized marker studies in determining the cause of an atypical cellular infiltrate of the skin. It also illustrates how leukemia cutis can masquerade as a clinically benign-appearing cutaneous eruption in a seemingly healthy patient with normal blood parameters.

Mucosal melanotic macule, reactive type: a simulation of melanoma.

Two patients with spontaneously resolving hyperpigmented patches of the oral mucosa are reported. Histologically, lesions in both cases showed large pigment-laden dendritic cells singly dispersed at all levels of the epidermis, which simulated in situ melanoma. The absence of such cells in the basal layer of the epidermis served to histologically distinguish these lesions from a biologically malignant melanocytic tumor. Spontaneous resolution in both patients suggests that the condition is reactive. We propose the term mucosal melanotic macule, reactive type, for this lesion, which has been described previously under the misnomer oral melanoacanthoma.