[Merkel cell carcinoma. Study of five cases].

Merkel cell carcinoma (MCC) is a rare malignant skin tumor of neuroendocrine origin with a poor prognosis and rapid progression. It is usually an erythematous nodule on the face, and is associated with other skin neoplasms. Its histology shows a large mass of small cells containing oval nuclei with powdery chromatin in the dermis.

Occupational allergic contact dermatitis from antioxidant amines in a dental technician.

We describe an 18-year-old dental technician who presented with dry hyperkeratotic lesions on his left palm that were limited to an area that was in contact with a container in which he had prepared the molds for a dental prosthesis. On patch testing, he had a positive reaction to black rubber mix and its components N-cyclohexyl-N'-phenyl-4-phenylenediamine, N,N'-diphenyl-4-phenylenediamine, and N-isopropyl-N'-phenyl-4-phenylenediamine, as well as to a piece of the rubber container. Thin-layer chromatography (TLC) of a piece of the rubber container confirmed the presence of the para-phenylenediamine mix.