The human keratins: biology and pathology

The keratins are the typical intermediate filament proteins of epithelia, showing an outstanding degree of molecular diversity. Heteropolymeric filaments are formed by pairing of type I and type II molecules. In humans 54 functional keratin genes exist. They are expressed in highly specific patterns related to the epithelial type and stage of cellular differentiation. About half of all keratins—including numerous keratins characterized only recently—are restricted to the various compartments of hair follicles. As part of the epithelial cytoskeleton, keratins are important for the mechanical stability and integrity of epithelial cells and tissues. Moreover, some keratins also have regulatory functions and are involved in intracellular signaling pathways, e.g. protection from stress, wound healing, and apoptosis. Applying the new consensus nomenclature, this article summarizes, for all human keratins, their cell type and tissue distribution and their functional significance in relation to transgenic mouse models and human hereditary keratin diseases. Furthermore, since keratins also exhibit characteristic expression patterns in human tumors, several of them (notably K5, K7, K8/K18, K19, and K20) have great importance in immunohistochemical tumor diagnosis of carcinomas, in particular of unclear metastases and in precise classification and subtyping. Future research might open further fields of clinical application for this remarkable protein family

Limb-Salvage Surgery of Soft Tissue Sarcoma with Sciatic Nerve Involvement

Background. The surgical resection of soft tissue sarcomas (STS) with sciatic nerve involvement presents a significant surgical and oncological challenge. Current treatment strategies pursue a multimodal approach with the aim of limb preservation. We aim to evaluate the outcomes of limb-sparing surgery of STS in a patient cohort and to propose a classification for STS with sciatic nerve involvement. Methods. Patients receiving limb-preserving resections for STS with sciatic nerve involvement between 01/2010 and 01/2017 were included. Clinical and oncological data were prospectively collected in a computerized database and retrospectively analyzed. Sciatic nerve involvement in STS was classified preoperatively as follows: type A for nerve encasement; type B for nerve contact; and type C for no nerve involvement. Results. A total of 364 patients with STS were treated, of which 27 patients had STS with sciatic nerve involvement. Eight patients with type A tumors (29.6%) underwent sciatic nerve resection, and 19 patients with type B tumors (70.4%) received epineural dissections. Disease progression was observed in 8 patients (29.6%) with a local recurrence of 11.1% and distant metastasis in 29.6%. The type of nerve resection significantly influenced leg function but had no impact on disease recurrence or overall survival. Conclusion. In a cohort of carefully selected patients with STS and sciatic nerve involvement, the extent of sciatic nerve resection had no significant impact on disease recurrence or survival. Precise classification of neural involvement may therefore be useful in selecting the appropriate degree of nerve resection, without compromising oncological outcome or unnecessarily sacrificing leg function