Differentiation of eccrine poroma cells to cytokeratin 1- and 10-expressing cells, the intermediate layer cells of eccrine sweat duct, in the tumor cell nests

Composition of the extracellular matrix of lymphatic novel threadlike structures: is it keratin?

Background. The lumen of novel threadlike structures (NTSs) is enclosed by a single layer of endothelial cells surrounded by extracellular matrix (ECM). We hypothesized that collagen may be a component of the ECM associated with lymphatic NTSs. Methods. Six female New Zealand white rabbits were anesthetized, and the NTS structures within lymphatic vessels were identified by contrast-enhanced stereomicroscopy or alcian blue staining. Isolated NTS specimens were stained with acridine orange, YOYO-1, and 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI). The structural and molecular composition of the ECM was investigated using transmission electron microscopy (TEM), electrospray ionization-mass spectrometry, and proteomic analysis. Results. The lymph vessel wall was stained red by DiI, and rod-shaped nuclei were stained green by YOYO-1. The area surrounding the NTS was also stained red and contained green rod-shaped nuclei. TEM images showed that the NTS consisted of many ECM fibers and the ECM fibers appeared to be ~100 nm in diameter and had narrowly spaced striated bands. Proteomic analysis of the lymphatic NTS-associated ECM identified 4 proteins: keratin 10, cytokeratin 3, cytokeratin 12, and soluble adenylyl cyclase. Conclusion. The TEM study suggested that the lymphatic NTS-associated ECM did not contain collagen. This was confirmed by proteomic analysis, which showed that keratin was the major component of the ECM.

New concepts on the histogenesis of eccrine neoplasia from keratin expression in the normal eccrine gland, syringoma and poroma

BACKGROUND

Peripheral and luminal layers of eccrine sweat gland ducts are self-renewing structures. Proliferation is restricted to the lowermost luminal layer, but randomly scattered in the peripheral layer. Each layer exhibits differential expression of keratins K5/K14 and K6/K16. Keratin K1 occurs only in peripheral cells and the novel keratin K77 is specific for luminal cells.

OBJECTIVES

To investigate the expression of luminal (K77), peripheral (K1) and further discriminatory keratins in two eccrine sweat gland tumours: syringoma, thought to show differentiation towards luminal cells of intraepidermal sweat ducts and eccrine poroma, considered to arise from poroid cells, i.e. peripheral duct cells; and keratinocytes of the lower acrosyringium/sweat duct ridge differentiating towards cells of intradermal/intraepidermal duct segments.

METHODS

Paraffin-embedded sections were examined by immunohistochemistry using several keratin, smooth muscle actin and Ki-67 antibodies.

RESULTS

We confirmed the ductal nature of syringomas. Despite drastic morphological alterations in both layers, their keratin patterns remained almost undisturbed compared with normal ducts. In eccrine poroma epidermal keratins K5/K14 were ubiquitously expressed in all poroid cells. Cell islands deviating morphologically from poroid cells contained epidermal keratins K1/K10. K77 expression was limited to luminal cells of intact duct structures within the tumours.

CONCLUSIONS

Syringomas are benign tumours of luminal cells of the lowermost intraglandular sweat duct. Poroid precursor cells of poromas do not comprise peripheral duct cells nor do poromas differentiate towards peripheral or luminal duct cells. Instead, poroid cells consist only of keratinocytes of the lowermost acrosyringium and the sweat duct ridge and poromas tend to differentiate towards the cells of the upper acrosyringium.

Expression of cytokeratin subtypes in intraepidermal malignancies: a guide for differentiation

BACKGROUND

Among intraepidermal malignancies of epithelial origin, Bowen's disease, bowenoid actinic keratosis (BAK), intraepidermal malignant eccrine poroma (MEP), and Paget's disease may pose diagnostic difficulties.

METHODS

Histologic features and immunohistochemical profiles of 24 cases of Bowen's disease, 21 cases of BAK, 18 cases of intraepidermal MEP, and 11 cases of Paget's disease were analyzed.

RESULTS

Using multivariate logistic regression test, multinuclear giant cells and solar degeneration were found to be the only histologic parameters of diagnostic help. On the other hand, a widespread positive reaction for CK 5/8, CK 7, CK 19, and negative reaction for CK 10, was a helpful feature in the differentiation of Paget's disease from Bowen's disease and BAK. The widespread and strong expression of CK 10 was seen in almost all cases of Bowen's disease in contrast to BAK. The widespread expression of CK 5/8 and CK 7, and negative reaction for CK 10, was in favor of Paget's disease, compared to intraepidermal MEP. On the other hand, widespread expression of CK 19 was a common finding in intraepidermal MEP, in contrast to Bowen's disease.

CONCLUSION

An immunohistochemical panel may provide significant hints on the differentiation of common intraepidermal malignancies, especially in problematic cases.

Histopathological and immunohistochemical studies of poroid hidradenoma

Poroid hidradenoma (PH), a less common subtype of poroid neoplasm (PN) than eccrine poroma (EP), has not been immunohistochemically studied before. Six cases of PH (four solitary PH and two PH coexisted with other types of PN) were included in the study. Fifteen cases of EP were also included for comparison. Hematoxylin and eosin, Masson-Zimmerman silver stain, and a variety of immunohistochemical stains were used. Microscopically, PH is not connected to the epidermis. All six PH contained small poroid cells and larger, paler cuticular cells. Some PH showed separate or clusters of sebocytes (2/6), horn cysts (1/6), juxtaposed lymphoid follicles in the stroma (1/6) and foci of keratohyaline granules (2/6), none of which was seen in the 15 EP. Immunohistochemically, the keratin distribution of PH was very similar to that of EP. PH has a very small number of Langerhans cells (significantly lower than the overlying epidermis, P=0.045), and a sparse deposition of melanin. We conclude that except the location, the histopathological and immunochemical differences between PH and EP were small. Sebaceous differentiation in two PH lesions suggested the possibility of an apocrine origin. The deeper parts of eccrine apparatus other than basaloid cells may have been more actively involved in the histogenesis of PH.

Cytokeratin 1 and gC1qR mediate high molecular weight kininogen binding to endothelial cells

High molecular weight kininogen (HK) attaches to endothelial cells by separate sites on the heavy and light chains and requires 15-50 microM zinc. Previously identified binding proteins include gC1qR, cytokeratin 1, and the urokinase plasminogen activator receptor; however, their relative contributions to binding are not yet clarified. We have prepared affinity columns to which were coupled either cleaved HK or peptide LDCNAEVYVVPWEKKIYPTVNCQPLGM derived from heavy-chain domain 3. Endothelial cell membranes were solubilized and chromatographed in the presence or absence of zinc ion, the bound proteins were eluted, and active fractions were identified by dot blot using biotinylated HK, SDS/PAGE, and Western blot analysis. The peptide containing column eluate revealed but one band at 68 kDa if zinc ion was present which was identified as cytokeratin 1 by amino acid sequencing of an internal peptide. The HK affinity column revealed bands at 68 kDa (cytokeratin 1), 33 kDa (gC1qR), and 66 kDa (unidentified). HK or domain 3-derived peptide bound to the 68 kDa band; prekallikrein and Factor XII did not. HK or Factor XII bound to the 33-kDa band if zinc was present while no binding to the 66 kDa band was observed. Antibody to cytokeratin 1 inhibited HK binding to endothelial cells by 30%, antibody to gC1qR inhibited HK binding to endothelial cells by 72%, and a mixture of both inhibited binding by 86%. Our data suggest HK binding by interaction of the heavy-chain domain 3 with cytokeratin 1 and the light chain with gC1qR.