[On the biologic phenomenon of epidermotropism (author's transl)]

Hidroacanthoma simplex with in situ porocarcinoma. A case suggesting malignant transformation

A case of hidroacanthoma simplex, suggesting malignant transformation into porocarcinoma in situ is reported. It represents further evidence that epidermotropic eccrine carcinoma may originate from the acrosyringium. This lesion demonstrates that the upper portion of the dermal eccrine duct may participate in the oncogenesis of hidroacanthoma simplex. It may also provide the missing link in the chain of evolution of benign eccrine poroacanthoma into porocarcinoma.

[The special relations of malignant skin lymphomas to the epidermis and to the epidermal appendages (author's transl)]

Epitheliotropia of malignant skin lymphomas is an unexplained phenomenon which equally affects epidermis and ectodermal appendages. This phenomenon is found especially in tumours of probable T-cell origin. However it can also be observed in B-cell lymphomas (immunocytomas) and is therefore not an exact criterium for the biological origin of a lymphoma. In the case of germinal center tumors we could not find evidence of epitheliotropia. An active invasion of neoplastic cellular infiltrate into the epithelium must be differentiated from the phenomenons caused by passive pressure, resulting from the expansion of the tumor. However, one has to remember that epitheliotropic malignant lymphomas invade the epidermis in all stages of development. It is shown, that Pautrier microabscesses are only a special non specific aspect of epidermotropia.