Trichilemmal carcinoma--a rare tumor: case report.

Trichilemmal carcinoma is a rare cutaneous cancer that usually occurs on photoexposed areas in elderly individuals. Most of the time, there is a unique lesion that presents a papulonodular aspect with possible keratosis or ulceration on the top of it. We report on a case of this rare tumor, discussing various aspects of this entity and possible therapy. Simple excision with adequate safety margin is a safe, low-cost and effective mode of treatment for this type of carcinoma. Although a rare form of neoplasia, trichilemmal carcinoma has good prognosis when treated correctly.

An emerging concept of prion infections as a form of transmissible cerebral amyloidosis.

Proteins are a major constituent of cells with specific biological functions. Besides the primary structure that is simply the sequence of amino acids that comprise a protein, the secondary structure represents the first step of folding defining its general conformation. The biological functions of proteins are directly dependent on the acquisition of their conformation. The same protein can have different stable states, which may participate with different functions in the cell. The amyloid diseases comprise Alzheimer's and Parkinson's diseases, type II diabetes mellitus and systemic amyloidosis. Amyloid fibers are insoluble, resistant to proteolysis and show an extremely high content of beta-sheet, in a very similar structure to the one observed among prion rods, associated to the transmissible spongiform encephalopathies. All these diseases are "infectious" in the sense that misfolded beta-sheeted conformers formed in a nucleation process in which preformed metastable oligomer acts as a seed to convert a normal isoform into an abnormal protein with a misfolded conformation. Only prion infections have a proven infectivity in a microbiological sense; some recent observations, however, detected the transmissibility of systemic amyloidosis by a prion-like mechanism among mice. Prions diseases and amyloidosis present many similar aspects of the so-called conformational diseases; according to this interpretation the prion infections could be considered as a form of transmissible cerebral amyloidosis.

Expression of keratins 14, 10 and 16 in marginal keratoderma of the palms.

Marginal keratoderma of the palms (MKP), also known as degenerative collagenous plaques of the hands, is an infrequent disease affecting individuals with photoaged skin and submitted to mechanical trauma of the hands. The aim of the study was to study the expression of keratin 14 (K14) in the basal layer and keratins 10 (K10) and 16 (K16) in the suprabasal layer, and to establish the effect of growth factors and receptors of the epidermal growth factor in the genesis of hyperkeratosis observed in MKP. The study included 14 patients with MKP. Expression of keratins 10, 14 and 16 was visualized by immunohistochemical staining using monoclonal antibodies by standard immunoperoxidase method. As control three normal skin samples were used. Absence or weak expression of keratins 14 and 10, and strong expression of keratin 16 was recorded in MKP patients. It was concluded that MKP patients present weak expression of keratins 14 (basal membrane) and 10 (suprabasal layer) but strong expression of keratin 16, emphasizing the importance of stimulation of epidermal growth factor receptors by ultraviolet radiation and traumatism.