Extraskeletal myxoid chondrosarcoma: A study of 17 cases focusing on the diagnostic utility of INSM1 expression and presenting rare morphological variants associated with non-EWSR1::NR4A3 fusions

Extraskeletal myxoid chondrosarcoma (EMC) is a rare sarcoma of uncertain lineage. Insulinoma-associated protein 1 (INSM1) has recently been described as a highly specific and sensitive immunohistochemical marker for EMC. The goal of this study was to evaluate the diagnostic significance of INSM1 immunohistochemistry in EMC. Furthermore, correlations between molecular and morphological findings were performed. Sixteen of 17 EMC cases were stained with the INSM1 antibody. Tumors with at least 5% INSM1-positive cells and any staining intensity were considered positive. Molecular testing was successfully performed in 12/17 cases. The immunohistochemical analysis detected 13 INSM1-positive (81%) and 3 INSM1-negative tumors (19%). The extent of the staining was classified as 1+ in 7 cases (44%), 2+ in 2 cases (13%), 3+ in 2 cases (13%) and 4+ in 2 cases (13%). Intensity of immunostaining was weak in 5 cases (31%), moderate in 2 cases (13%) and strong in 6 cases (38%). Molecular assays revealed 8 EWSR1::NR4A3 positive tumors (67%), 2 TAF15::NR4A3 positive tumors (17%), 1 TCF12::NR4A3 positive tumor (8%) and 1 NR4A3 positive tumor (8%) in which no other gene alteration was identified. Two of them, namely TCF12 positive and one TAF15 positive tumors, were highly cellular and partially associated with pseudopapillary architecture. Our study found that moderate/strong expression of INSM1 in more than 25% of tumor cells was present in only 31% of cases. Thus, the diagnostic utility of INSM1 is rather low. Two morphologically unique cases of non-EWSR1 rearranged EMC with an extremely rare pseudopapillary growth pattern are also reported.

Morphogenesis of Olfactory Organ of Bushymouth Catfish Ancistrus dolichopterus (Teleostei: Loricariidae) before Switching to Exogenous Feeding

Olfaction plays an important role in a fish's life. Its value may differ at different developmental stages, depending on the feeding style of the species. The goal of the present study was to investigate the olfactory organ of a species that feeds mainly on algae- the bushymouth catfish, Ancistrus dolichopterus-at developmental stages from olfactory placode to the definitive olfactory chamber. For this study, we used light and electron (scanning) microscopy. The topography of the olfactory placode of A. dolichopterus is typical for teleostei. Formation of olfactory pit takes place at the same time as rostral elevation formation. Rostral elevation participates in the formation of the nasal bridge and anterior tubular nostril. It was found out that the anlage of olfactory rosette in A. dolichopterus arises earlier than in most teleostei. However, the number of lamellae does not increase until switching to exogenous feeding. We suppose that the early development of olfactory organ is necessary for intraspecific communication, not just for finding food.

Fate of the molar dental lamina in the monophyodont mouse

The successional dental lamina (SDL) plays an essential role in the development of replacement teeth in diphyodont and polyphyodont animals. A morphologically similar structure, the rudimental successional dental lamina (RSDL), has been described in monophyodont (only one tooth generation) lizards on the lingual side of the developing functional tooth. This rudimentary lamina regresses, which has been proposed to play a role in preventing the formation of future generations of teeth. A similar rudimentary lingual structure has been reported associated with the first molar in the monophyodont mouse, and we show that this structure is common to all murine molars. Intriguingly, a lingual lamina is also observed on the non-replacing molars of other diphyodont mammals (pig and hedgehog), initially appearing very similar to the successional dental lamina on the replacing teeth. We have analyzed the morphological as well as ultrastructural changes that occur during the development and loss of this molar lamina in the mouse, from its initiation at late embryonic stages to its disappearance at postnatal stages. We show that loss appears to be driven by a reduction in cell proliferation, down-regulation of the progenitor marker Sox2, with only a small number of cells undergoing programmed cell death. The lingual lamina was associated with the dental stalk, a short epithelial connection between the tooth germ and the oral epithelium. The dental stalk remained in contact with the oral epithelium throughout tooth development up to eruption when connective tissue and numerous capillaries progressively invaded the dental stalk. The buccal side of the dental stalk underwent keratinisation and became part of the gingival epithelium, while most of the lingual cells underwent programmed cell death and the tissue directly above the erupting tooth was shed into the oral cavity.

A new type of plasma knife and its effect on biological issues--a pilot study

BACKGROUND

Currently, several types of plasma discharge devices have become established for performing surgical procedures or superficial sterilization. Our goal is to introduce a brand new type of plasma discharge device with different characteristics, which we have used for two experiments involving thermal damage to biological tissues.

MATERIAL AND METHODS

A plasma discharge device with the following characteristics was used for all incisions in plasma group: radio frequency barrier discharger at atmospheric pressure with a working frequency of 13.56 MHz. The working gas was Argon. We used a Cesar 136 generator with typical power 100-150W and with a working gas flow rate between 0.5 and 3 litres per minute. The inner diameter of the end of the nozzle was 0.4mm. A standard Martin electrotome was used for all comparative incisions in the electrotome group. We used two experimental fresh rat cadavers, employing their skin, tails, lungs, livers, kidneys and spleens to make a comparative study between incisions made with a plasma discharge knife and those made with a standard electrotome device. All samples underwent histological verification.

DISCUSSION

Our experiment showed slight differences in the impact on incision edges made by the plasma knife and the electrotome. The most interesting effect is on the skin: the plasma knife does not damage hair bulbs, and it results in less thermal damage. The plasma discharge knife is a promising device for cutting various biological tissues. Its effect can be compared with a standard electrotome, while in some tissues it causes less harm then an electrotome. Moreover, we can adjust its therapeutic effect. However, we do not consider the plasma knife a better choice at present, because maneuvering it is unwieldy.

Woven vascular microsurgical prostheses in our experimental practice

The authors have been concerned for six years with the development of woven microsurgical prostheses in experiments on laboratory rats, beagle dogs and domestic white pigs. In rats, in 224 experiments employing 38 types of prostheses with an inner diameter of 2 mm, a reliable prosthesis was selected, described as No. 36, with a 100% patency after insertion of a 1 cm long portion into a defect in the abdominal aorta in 40 experiments. The follow-up of this type of prosthesis lasted 12 months. In large animals this type of prosthesis was implanted into a defect of the radial artery and cephalic vein in dogs and into the femoral artery and the artery of a vascular pedicle of groin and lateral thigh flap. These experiments on large animals are not yet complete and will be the subject of a separate paper.