Residual Bioprosthetic Valve Immunogenicity: Forgotten, Not Lost

Despite early realization of the need to control inherent immunogenicity of bioprosthetic replacement heart valves and thereby mitigate the ensuing host response and its associated pathology, including dystrophic calcification, the problem remains unresolved to this day. Concerns over mechanical stiffness associated with prerequisite high cross-link density to effect abrogation of this response, together with the insinuated role of leaching glutaraldehyde monomer in subsequent dystrophic mineralization, have understandably introduced compromises. These have become so entrenched as a benchmark standard that residual immunogenicity of the extracellular matrix has seemingly been relegated to a very subordinate role. Instead, focus has shifted toward the removal of cellular compartment antigens renowned for their implication in the failure of vascularized organ xenotransplants. While decellularization certainly offers advantages, this review aims to refocus attention on the unresolved matter of the host response to the extracellular matrix. Furthermore, by implicating remnant immune and inflammatory processes to bioprosthetic valve pathology, including pannus overgrowth and mineralization, the validity of a preeminent focus on decellularization, in the context of inefficient antigen and possible residual microbial remnant removal, is questioned.

Abcc6 null mice a model for mineralization disorder PXE show vertebral osteopenia without enhanced intervertebral disc calcification with aging

Chronic low back pain is a highly prevalent health condition intricately linked to intervertebral disc degeneration. One of the prominent features of disc degeneration that is commonly observed with aging is dystrophic calcification. ATP-binding cassette sub-family C member 6 (ABCC6), a presumed ATP efflux transporter, is a key regulator of systemic levels of the mineralization inhibitor pyrophosphate (PPi). Mutations in ABCC6 result in pseudoxanthoma elasticum (PXE), a progressive human metabolic disorder characterized by mineralization of the skin and elastic tissues. The implications of ABCC6 loss-of-function on pathological mineralization of structures in the spine, however, are unknown. Using the ABCC6 -/- mouse model of PXE, we investigated age-dependent changes in the vertebral bone and intervertebral disc. ABCC6 -/- mice exhibited diminished trabecular bone quality parameters at 7-months which remained significantly lower than the wild-type mice at 18 months-of-age. ABCC6 -/- vertebrae showed increased TRAP staining along with decreased TNAP staining, suggesting an enhanced bone resorption as well as decreased bone formation. Surprisingly, however, loss of ABCC6 resulted only in a mild, aging disc phenotype without evidence of dystrophic mineralization. Finally, we tested the utility of oral K3Citrate to treat the vertebral phenotype since it is shown to regulate hydroxyapatite mechanical behavior. The treatment resulted in inhibition of osteoclastic response and an early improvement in mechanical properties of the bone underscoring the promise of potassium citrate as a therapeutic agent. Our data suggest that although ectopic mineralization is tightly regulated in the disc, loss of ABCC6 compromises vertebral bone quality and dysregulates osteoblast-osteoclast coupling.

NIMG-28. PROSPECTIVE HISTOPATHOLOGY-VALIDATED MACHINE LEARNING FOR DISTINGUISHING TRUE PROGRESSION FROM TREATMENT-RELATED CHANGES IN GLIOBLASTOMA PATIENTS

PURPOSE Decision making about the best course of treatment for glioblastoma patients becomes challenging when a new enhancing lesion appears in the vicinity of the surgical bed on follow-up MRI (after maximal safe tumor resection and chemoradiation), raising concerns for tumor progression (TP). Literature indicates 30-50% of these new lesions describe primarily treatment-related changes (TRC). We hypothesize that quantitative analysis of specific and sensitive features extracted from multi-parametric MRI (mpMRI) via machine learning (ML) techniques may yield non-invasive imaging signatures that distinguish TP from TRC and facilitate better treatment personalization. METHODS We have generated an ML model on a retrospective cohort of 58 subjects, and prospectively evaluated on an independent cohort of 58 previously unseen patients who underwent second resection for suspicious recurrence and had availability of advanced mpMRI (T1, T1-Gd, T2, T2-FLAIR, DTI, DSC). The features selected by our retrospective model, representing principal components analysis of intensity distributions, morphological, statistical, and texture descriptors, were extracted from the mpMRI of the prospective cohort. Integration of these features revealed signatures distinguishing between TP, mixed response, and TRC. Independently, a board-certified neuropathologist evaluated the resected tissue by blindly classifying it in the above three categories, based on mitotic figures, pseudopalisading necrosis, geographic necrosis, dystrophic calcification, vascular changes, and Ki67. RESULTS Tissues classified as TRC by the neuropathologist were associated with imaging phenotypes of lower angiogenesis (DSC-derived features), lower cellularity (DTI-derived features), and higher water concentration (T2, T2-FLAIR features). Our ML model characterized TP with 78% accuracy (sensitivity:86%, specificity:70%, AUC:0.80 (95%CI, 0.68-0.92)) and TRC with 81% accuracy (sensitivity:80%, specificity:81%, AUC:0.87 (95%CI, 0.72-1.00)). CONCLUSION Our proposed ML model reveals distinct non-invasive markers of TP and TRC, directly associated with histopathological changes in prospective glioblastoma patients. Reliable stratification of TP and TRC entities may help to noninvasively determine whether the course of treatment should change.

Ameloblastoma: relato de caso com recidiva extra-óssea após 32 anos

Ameloblastoma is a benign odontogenic tumor with local, invasive growth and late recurrence. The aim of this paper is report a case with recurrence after 32 years. The patient was 52 year-old, female and presented to the Santa Casa Hospital Complex with a complain of oral swelling of 5 years duration, in the right mandibular body region. The area produced sleep apnea, mastigatory and speech problems. Microscopic exam reveled ameloblastoma with cystic degeneration and dystrophic calcification.

Heavily Calcified Gastrointestinal Stromal Tumour of Stomach: A Diagnostic Dilemma

Gastrointestinal stromal tumours (GIST) are the most common mesenchymal tumour of gastrointestinal tract and the stomach being the most commonly involved organ. Focal calcification may be seen in GIST but prominent or heavy calcification is rare. Gastric mass with prominent calcification on imaging may create a diagnostic dilemma. We present a rare case of gastric GIST with heavy calcification in a 55 years old female presenting with abdominal lump. Computed tomography (CT) showed a large heterogenous juxta gastric mass with solid-cystic component with heavy calcification. She underwent laparotomy and en-bloc gastric sleeve resection with the mass. Microscopic examination showed tumour with spindle cell and calcification with mitotic index of 6/50 High power field. Immunoreactivity with Vimentin, CD34 and DOG 1 confirmed diagnosis of GIST. Dystrophic calcification of necrotic or degenerative tissue is thought to be cause of calcification in GIST. Very few cases of heavily calcified GIST have been reported in literature, our case is of interest because presence of solid cystic component and a huge size ~ 14 cm (longest diameter).

Magnetic resonance imaging findings in children with Parry-Romberg syndrome and en coup de sabre

Background The aim of this study was to: (i) describe the abnormalities seen on brain imaging in a group of children with en coup de sabre (EDCS) with/without Parry-Romberg syndrome (PRS); and (ii) identify clinical predictors of brain imaging abnormalities. Methods This was a single centre (Great Ormond Street Hospital, London) retrospective case series of patients with ECDS/PRS seen from 2000 to 2018. We identified patients with cutaneous manifestations consistent with the clinical descriptions of ECDS/PRS. Presenting clinical, laboratory, and radiological brain findings are described. Results are expressed as medians and ranges or frequencies and percentages. Fisher’s exact test was used to identify clinical associations with magnetic resonance imaging (MRI) abnormalities. Results Fourteen patients were studied: 6 males and 8 females; median age 14 years (range 3–20). We observed neuroimaging abnormalities in 2/6 ECDS and 5/8 ECDS/PRS patients. White matter signal abnormality, dystrophic calcification, leptomeningeal enhancement, and sulcal crowding were the typical findings on brain imaging. A total of 50% of patients had no MRI abnormality despite some of these patients having neurological symptoms. The presence of seizures was significantly associated with ipsilateral enhanced white matter signalling on MRI (p < 0.05). Conclusions In summary, we observed several distinct radiographic patterns associated with ECDS/PRS. Seizure disorder was strongly associated with the presence of ipsilateral enhanced white matter signalling. Improved neuroimaging techniques that combine morphological with functional imaging may improve the detection rate of brain involvement in children with ECDS/PRS in the future.

Role of patients associations in connective tissue calcifiying diseases: a position statement from EuroSoftCalc.Net group

Patients have been showing a growing interest in taking active participation in decision making, and having the opportunity to drive clinical investigation. This is more common for patients who have a rare disease than for those with more prevalent diseases. The EuroSoftCalc.Net COST Action, a group of clinicians and researchers involved in the dystrophic calcification process held a meeting in which three representatives of patients’ associations, coming from Portugal, France and Spain, discussed the role of patients and their associations, namely in the Action, and also the main concerns in their countries. The disparities in health care between European Union countries with regard to connective tissue calcifying diseases, and the existing conflicts of interest, were a matter of debate during the meeting. As a consequence of the presentations and the debate that followed, it became clear that, despite their countries, the main concerns of the patients are identical, namely a lack of specific therapy and follow-up clinical guidelines, delays in the diagnosis, difficulties in getting members to enrol to associations, and/or difficulties with doctors’ explanations for the diseases. The attendees also agreed that EuroSoftCalc.Net group should help to set up new associations where no Patient Associations presently exist, and, furthermore, should release diagnosis and follow-up guidelines, especially helpful in countries, and/or for diseases, where no multidisciplinary consultations are available.