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Primary gastric yolk tumours are extremely rare. We report a 52-year-old male who presented to the Sultan Qaboos University Hospital, Muscat, Oman, in 2017 after having undergone a gastrectomy abroad due to a suspected poorly-differentiated adenocarcinoma. The patient subsequently returned to Oman to receive chemotherapy. However, while undergoing chemotherapy, an abdominal computed tomography scan revealed a lobulated mesenteric mass. Microscopic examination of the resected lesion confirmed a diagnosis of a yolk sac tumour. The mass was diffusely positive for α-fetoprotein (AFP) and a gastric carcinoma stain was negative. Gastrectomy slides from the patient’s previous surgery were examined retrospectively. The morphology was typical for a yolk sac tumour and was negative for epithelial markers. An AFP stain showed diffuse immunoreactivity. Thus, the patient was deemed to have had a primary gastric yolk sac tumour which had later metastasised to the mesocolon. Germ cell tumour protocols were initiated and the patient responded well to treatment. Keywords: Yolk Sac Tumor; Germ Cell Tumor; Gastrectomy; Metastasis; Diagnostic Errors; Case Report; Oman.

Rosai-Dorfman disease (RDD) is a rare benign proliferative histiocytic disorder characterised by massive lymphadenopathy. While extranodal involvement can occur in generalised RDD, isolated soft tissue RDD (STRDD) is extremely rare. We report a 17-year-old male patient who presented to the maxillofacial outpatient department of the Sultan Qaboos Hospital, Salalah, Oman, in 2015 with a painless cheek mass which had been slowly growing over the previous two months. Routine histopathological examinations and immunohistochemistry confirmed a diagnosis of STRDD. Currently, surgical excision is considered to be the most effective curative treatment for STRDD, as the outcomes of other treatment modalities are still unknown. Despite its rarity, STRDD should be considered in the differential diagnosis of histiocytic soft tissue lesions.

Follicular dendritic cell sarcoma (FDCS) is a rare neoplasm with a non-specific and insidious presentation further complicated by the difficult diagnostic and therapeutic assessment. It has a low to intermediate risk of recurrence and metastasis. Unlike other soft tissue sarcomas or histiocytic and dendritic cell neoplasms, cytogenetic studies are very limited in FDCS cases. Although no specific chromosomal marker has yet been established, complex aberrations and different ploidy types have been documented. We report the case of a 39-yearold woman with FDCS who presented to the Sultan Qaboos University Hospital in Muscat, Oman, in February 2013. Ultrastructural, immunophenotypical and histological findings are reported. In addition, karyotypic findings showed deletions of the chromosomes 1p, 3q, 6q, 7q, 8q and 11q. To the best of the authors’ knowledge, these have not been reported previously in this tumour. Techniques such as spectral karyotyping may help to better characterise chromosomal abnormalities in this type of tumour.

Objectives: Mutations/deletions affecting the TP53 gene are considered an independent marker predicting a poor prognosis for patients with diffuse large B-cell lymphoma (DLBCL). A cohort within a genetically isolated population was investigated for p53 mutation/deletion status. Methods:Deoxyribonucleic acid (DNA) samples were extracted from 23 paraffin-embedded blocks obtained from DLBCL patients, and subjected to polymerase chain reaction (PCR) amplification and sequencing of exons 4–9 of the p53 gene. Results: While 35% of patients analysed displayed allelic deletions (P

INTRODUCTION:MicroRNAs (miRNAs) are small non-coding RNA that plays a vital role in cancer progression. Neo-adjuvant chemotherapy (NAC) has become the standard of care for locally advanced breast cancer. The aim of this study was to evaluate miRNA alterations during NAC using multiple samples of tissue and serum to correlate miRNA expression with clinico-pathological features and patient outcomes. METHODS:Tissue and serum samples were collected from patients with locally advanced breast cancer undergoing NAC at four time points: time of diagnosis, after the first and fourth cycle of doxorubicin/cyclophosphamide treatment, and after the fourth cycle of docetaxel administration. First, we evaluated the miRNA expression profiles in tissue and correlated expression with clinico-pathological features. Then, a panel of four miRNAs (miR-451, miR-3200, miR-21, and miR-205) in serum samples was further validated using quantitative reverse-transcription polymerase chain reaction (RT-qPCR). The alterations in serum levels of miRNA, associations with clinical and pathological responses, correlation with clinico-pathological features, and survival outcomes were studied using Friedman, Mann-Whitney U, and Spearman, Wilcoxon signed-ranks tests. P≤0.05 was considered statistically significant. RESULTS:We analyzed 72 tissue samples and 108 serum samples from 9 patients and 27 patients, respectively. MicroRNA expression profiling of tumor versus normal tissue revealed more than 100 differentially expressed miRNAs. Serum miR-451 levels were significantly decreased during treatment, and higher serum levels were associated with improved clinical and pathological responses and disease-free survival. This is one of the early reports on miR-3200 in response to treatment in breast cancer, as serum levels of miR-3200 found to decline during NAC, and higher serum levels were associated with lower residual breast cancer burden and relapse rates at time of diagnosis. CONCLUSION:Variations in serum miRNA levels during NAC treatment may be therapeutically significant for predicting response and survival outcomes.

Plasma cell myeloma is an uncommon disease which, besides primarily involving the bone marrow, has a tendency to involve other organs thus presenting with different clinical manifestations. While pleural effusions are infrequent in this disease, true myelomatous pleural effusions are extremely rare. We report the case of a middle-aged Omani man with relapsed plasma cell myeloma who developed bilateral pleural effusions. The diagnosis of myelomatous pleural effusion was made by finding many abnormal plasma cells as well as a high level of a monoclonal protein (IgG κ) in the pleural fluid. In spite of a good initial response to therapy, the patient had progressive disease and died 6 months later with bacterial sepsis. We present a review of the literature that indicates the rarity of such a manifestation and its association with poor prognosis and short survival.

Follicular dendritic cell sarcoma (FDCS) is a rare neoplasm with a non-specific and insidious presentation further complicated by the difficult diagnostic and therapeutic assessment. It has a low to intermediate risk of recurrence and metastasis. Unlike other soft tissue sarcomas or histiocytic and dendritic cell neoplasms, cytogenetic studies are very limited in FDCS cases. Although no specific chromosomal marker has yet been established, complex aberrations and different ploidy types have been documented. We report the case of a 39-yearold woman with FDCS who presented to the Sultan Qaboos University Hospital in Muscat, Oman, in February 2013. Ultrastructural, immunophenotypical and histological findings are reported. In addition, karyotypic findings showed deletions of the chromosomes 1p, 3q, 6q, 7q, 8q and 11q. To the best of the authors’ knowledge, these have not been reported previously in this tumour. Techniques such as spectral karyotyping may help to better characterise chromosomal abnormalities in this type of tumour.

A16-year-old girl presented with progressive left neck swelling of six weeks duration associated with low-grade fever and rash. Four weeks before visiting our institute, she was started on antibiotics combined with non-steroidal anti-inflammatory drugs (NSAIDs) prescribed by a doctor from a local health center. As a result, her pain resolved while the size of the swelling had an interval regression followed by rebound enlargement.

Ewing′s sarcoma/primitive neuroectodermal tumor (ES/PNET) of the prostate is extremely rare. Here, we report a case of ES/PNET of prostate in a 24-year-old man presenting with dysuria and pelvic discomfort. Computed tomography scan revealed a heterogeneous mass involving the prostate without evidence of distant metastases. Histologically, the tumor was composed of small round blue cells strongly and diffusely positive for CD99 and epithelial markers. Fluorescence in situ hybridization confirmed rearrangement of the Ewing′s sarcoma region on chromosome 22.