Asem Shalaby

Background: Odontogenic carcinoma with dentinoid (OCD) is a rare, poorly characterised tumour not yet included in the WHO classification of head and neck tumours. We report a rare case of OCD involving the temporal bone. Case presentation: A 35-year-old male presented with longstanding facial nerve paralysis and progressive hearing loss. Radiological investigation revealed an erosive mass in the temporal bone. The tumour was successfully resected, and definitive histopathological analysis showed a picture of OCD. The patient received adjuvant radiotherapy and remains under close surveillance for recurrence. Conclusions: This case broadens the anatomical spectrum of OCD and highlights the need to consider odontogenic tumours in the differential diagnosis of temporal bone lesions, despite their rarity at this site.

Case: A 20-year-old man carried a 33-cm diaphyseal femoral defect after childhood osteosarcoma and three failed reconstructions — distraction osteogenesis, autografting and the induced-membrane (Masquelet) technique. As a final limb-salvage attempt, a patient-specific 3D-printed polycaprolactone–tricalcium phosphate (PCL-TCP) scaffold was implanted over an intramedullary nail and bioactivated with iliac-crest bone marrow aspirate, followed at nine months by reamer-irrigator-aspirator autograft. Biopsy at that second procedure confirmed new osteoid and thick-walled vessels at the scaffold interface, yet radiographic consolidation never followed. Four weeks later Staphylococcus haemolyticus infection supervened, and after serial debridement the scaffold was explanted. At four years the limb is preserved and the patient walks independently with a mild limp and a radiographically fused knee. Conclusion: Histological osteogenesis without radiographic union indicates a construct that was biologically alive but biologically outpaced. Three determinants — a defect roughly twice the length at which scaffold-guided regeneration has succeeded, a scarred and hypovascular host bed, and a staged bioactivation protocol whose repeated open re-entries were themselves the infective exposure — argue that defect length, host vascularity and cumulative infection risk, rather than scaffold chemistry alone, should govern candidate selection for this technology.

Background Mutations in mismatch repair (MMR) genes play a crucial role in the pathogenesis of colorectal carcinoma (CRC), accounting for 10% to 15% of sporadic cases and up to 90% of hereditary non-polyposis cases. Reduced expression of the two transcription factors CDX2 and SATB2 has been linked to poor patient survival. The primary objective of this study was to evaluate the expression of mismatch repair proteins (MLH1, MSH2, MSH6, PMS2), along with CDX2 and SATB2, in relation to clinicopathologic characteristics and the survival outcome. Material and methods The study included 97 CRC patients with colectomy specimens received in the Pathology Department at Mansoura University during the period from 2011 to 2015. Immunohistochemistry for MLH1, MSH2, MSH6, PMS2, CDX2, and SATB2 was applied to tissue microarrays constructed from the patients’ paraffin blocks. Results Out of the 97 CRC patients examined, 38.1% (n = 37) showed MMR deficiency, whereas 61.9% (n = 60) showed intact MMR expression. Twenty-one cases showed combined loss of two proteins: MLH1/PMS2 (n = 15) and MSH2/MSH6 (n = 6), while 13 cases showed loss of only one protein. A significant correlation between MMR deficiency and the patient gender, the right-sided location, and the low score of tumor-budding was noted (p-values of 0.045, 0.002, and 0.001, respectively). The overall MMR deficiency showed no statistically significant association with SATB2 expression score, while isolated MSH2 deficiency showed a significant association with SATB2 expression (p = 0.004). The disease-free survival (DFS) and overall survival (OAS) showed no significant association with MMR deficiency, CDX2, and SATB2 expression scores. A shorter DFS was noted with older age and rectal location (p = , p = .,, respectively), while shorter OAS was noted with older age and high tumor-budding (p = 0.046, p = 0.001, respectively). Conclusion The MMR deficiency showed a significant association with the male gender, the right-sided location, and the low score of tumor-budding, and this may influence the prognosis and management plans. The relation between loss of SATB2, CDX2, and MMR protein expression needs further studies to be validated as a potential pathogenetic mechanism and as promising therapeutic targets.

Colorectal cancer (CRC) is a major public health challenge in Oman and a leading cause of cancer-related mortality. The rising incidence has been associated with lifestyle changes, urbanization, and genetic factors. The CRC Subtyping Consortium has defined four consensus molecular subtypes (CMS1–CMS4); however, data on their distribution in the Gulf region, including Oman, remain limited. This study aimed to characterize the distribution of CMS subtypes in Omani CRC patients and assess their clinicopathologic correlations using a practical immunohistochemistry (IHC) panel supplemented by a limited targeted molecular approach. This study included 273 CRC patients diagnosed between 2023 and 2024 at two major referral hospitals in Muscat. Initially, the mismatch repair (MMR)-deficient tumors (dMMR) were assigned as CMS1, while the MMR-proficient (pMMR) tumors were further evaluated for β-catenin, P53, KRAS, and TGF-β expression. Mutations in BRAF, TP53, and KRAS were analyzed by sequencing. The cohort comprised 51.6% males, with a mean age of 59.1 years. Most tumors were left-sided (70.7%). dMMR (CMS1) comprised 31 cases (11.35%). Out of the pMMR tumors, 111 cases (40.65%) showed positive expression of β-catenin and P53 (CMS2), 63 cases (23.0%) showed KRAS mutations (CMS3), and 68 cases (24.9%) showed TGF-β-positive expression (CMS4). The cases were predominantly concentrated in Muscat (41%). This study demonstrated the feasibility and clinical relevance of CMS-based classification in Oman and its potential role in precision oncology and healthcare planning.

The rising incidence and mortality of early-onset colorectal cancer (EOCRC) emphasize the urgent need for effective non-invasive screening. Circulating microRNAs (miRNAs) have emerged as promising biomarkers for cancer detection. This systematic review aims to evaluate the diagnostic performance of circulating miRNAs in detecting colorectal cancer (CRC). A literature search was conducted in PubMed and Scopus. Studies that report sensitivity, specificity, or area under the curve (AUC) for CRC detection by miRNA were included. The miRNA miR-21 was the most frequently studied biomarker, with a varying range of AUC from 0.55 to 0.973 attributed to differences in study populations and methodologies. The miRNAs miR-210 and miR-1246 showed potential diagnostic capacity with miR-1246 achieving an AUC of 0.924, 100% sensitivity, and 80% specificity. The miRNA panels offer improved diagnostic performance compared to individual miRNA. The best performing panel for CRC patients below 50 is miR-211 + miR-25 + TGF-β1 with AUC 0.99 and 100 specificity and 97 sensitivity. Circulating miRNAs hold significant promise as non-invasive biomarkers for CRC screening. However, the variability in diagnostic performance highlights the need for a standardized method and robust validation studies. Future research should focus on large-scale, ethnically diverse cohorts to establish clinically relevant miRNA biomarkers for CRC, particularly in younger populations.

Erdheim-Chester disease (ECD) is a rare form of non-Langerhans cell histiocytosis with unknown etiology. It is recently recognized to be neoplastic with genetic mutations affecting the mitogen-activating protein kinase (MAPK) pathway. We here present a case of a 49-year-old female who initially presented in 2012 with bilateral facial masses to a tertiary care center. These were removed but later recurred over a period of ten years. She then presented with xanthelasmas, bone lesions, secondary infertility due to hypothalamic hypogonadism, diabetes insipidus, and Hashimoto’s hypothyroidism. The facial masses were biopsied, and they showed classic morphological features in the form of diffuse infiltration by foamy histiocytes, with scattered Touton type of giant cells, patchy lymphocytic infiltrates, and dense fibrosis. The presented ECD case is particularly interesting due to the recurrent bilateral facial masses. To the best of our knowledge, this is the first documented case in Oman. The patient is stable and is being followed up in the clinic.