Purpose. Microsatellite instability (MSI) caused by mismatch repair protein (MMRP) deficiency is detected in 15% of sporadic colorectal cancers (CRCs). Our aim is to investigate the frequency of MMRP deficiency in young CRC patients, using immunohistochemical analysis. Methods. This study targeted cases of CRC at King Hussein Cancer Center from 2004 until 2012 in patients 45 years of age or younger at the time of diagnosis. Clinicopathological data was obtained from 155 patients’ records. Immunohistochemistry for MLH1, MSH2, PMS2, and MSH6 proteins was performed on paraffin-embedded tissue containing carcinoma. Results. The median age of patient at diagnosis was 38 years. A total of 29 (19%) cases showed deficient MMRP(dMMRP)expression. Loss of expression of PMS2 was seen in 17 cases, 12 cases of which showed loss of MLH1 expression. Loss of expression of MSH6 was seen in 10 cases, 9 of which showed loss of MSH2 expression. One case (3.4%) showed loss of all four MMR proteins, and another case (3.4%) showed loss of PMS2/MLH1 and MSH6. There was a significant association between abnormal MMR protein expression and tumor location proximal to splenic flexure (p value 0.000), pathologic features suggestive of microsatellite instability (p value 0.000), P53 negativity (p value 0.000), and stage (p value 0.02). Patients with dMMRP CRC appeared to have a significantly better overall survival compared to patients with proficient MMRP(pMMRP)(p value 0.02). Loss of MSH2/MSH6 was significantly associated with positive family history of cancer (p value = 0.020). Conclusions. The prevalence of dMMRP tumors in this age group appears to be similar to international literature. dMMRP tumors tends to be associated with earlier stages and better outcomes compared to pMMRP cases. dMMRP can serve as a biomarker for better prognosis. These results are of value in directing the clinical management of young patients with CRC.

Background/Objectives: Adult medulloblastoma is a rare entity, with management data extrapolated from pediatric medulloblastoma cases. We aim to report the clinical characteristics, prognostic factors, and treatment outcome of a cohort of adult patients with medulloblastoma. Methods: Fifty-three patients aged ≥ 18 years with medulloblastoma treated at King Hussein Cancer Center between 2007 and 2019 were retrospectively reviewed. Patients’ diseases were staged according to modified Chang’s staging system. All patients received adjuvant craniospinal irradiation followed by a posterior fossa boost. Baseline disease characteristics, including molecular subgrouping, were tested as prognostic factors of progression-free survival (PFS) and overall survival (OS) by using univariate analysis. Results: Median follow-up was 70 months (range 37.5–104.5 months). Twenty-two tumors were of the SHH-activated subtype. Conversely, WNT-activated and group 4 tumors had three cases each. Only 37.7% of patients died. The mean 3-year, 5-year, and 10-year OS were 85% (75–95%), 74% (62–87%), and 50% (33–75%), respectively. Significant differences in OS were associated with the extent of surgery (p = 0.017), M stage (p = 0.009), and risk status (p < 0.001). Relapses were detected in 28.3% of cases. The 3-year, 5-year, and 10-year PFS were 81% (71–92%), 75% (63–88%), and 66% (52–83%), respectively. Significant differences in PFS were associated with the extent of surgery (p = 0.008) and risk status (p = 0.012). Molecular subgrouping did not correlate with OS or PFS. Conclusions: Our results revealed poor survival of patients with high-risk disease, which may necessitate the intensification of chemotherapy. Molecular subgrouping did not correlate with the outcome in this cohort.

Mixed sex cord–stromal tumors, which consist of poorly differentiated Sertoli cells and Leydig cells and juvenile granulosa cell tumor tissue, are extremely rare. Most of these tumors are unilateral and stage I at the time of diagnosis; nonetheless, according to the available relevant English-language literature, these tumors maintain a malignant potential. We herein report a case involving a 15-year-old girl diagnosed with a mixed sex cord–stromal tumor (gynandroblastoma with juvenile granulosa cell tumor component). Left salpingo-oophorectomy was initially performed, and the diagnosis of a juvenile granulosa cell tumor was established. Right salpingo-oophorectomy was performed 1 year later, at which time the specimen showed a different growth pattern involving epithelioid cells and tubules, resembling a Sertoli–Leydig cell tumor. Immunohistochemical staining was performed and the specimen was compared with that obtained 1 year earlier. We concluded that the tumors were linked and most likely constituted a gynandroblastoma (mixed form of sex cord–stromal tumor). Although this is an extremely uncommon ovarian tumor, it should be considered when diverse tumor morphology is identified. Bilateral metachronous involvement of the ovaries is possible. The grade of the Sertoli–Leydig cell component may influence the prognosis of such a tumor.

Background: Breast cancer, particularly triple-negative breast cancer (TNBC), poses a significant global health burden. Chemotherapy was the mainstay treatment for TNBC patients until immunotherapy was introduced. Studies indicate a noteworthy prevalence (0.2% to 18.6%) of mismatch repair protein (MMRP) deficiency in TNBC, with recent research highlighting the potential of immunotherapy for MMRP-deficient metastatic breast cancer. This study aims to identify MMRP deficiency in TNBC patients using immunohistochemistry. Methods: A retrospective cohort study design was used and included TNBC patients treated between 2015 and 2021 at King Hussein Cancer Center. Immunohistochemistry was conducted to assess MMRP expression Results: Among 152 patients, 14 (9.2%) exhibited deficient MMR (dMMR). Loss of PMS2 expression was observed in 13 patients, 5 of whom showed loss of MLH1 expression. Loss of MSH6 and MSH2 expression was observed in one patient. The median follow-up duration was 44 (3–102) months. Despite the higher survival rate (80.8%, 5 years) of dMMR patients than of proficient MMR patients (62.3%), overall survival did not significantly differ between the two groups. Conclusion: Approximately 9% of TNBC patients exhibit dMMR. dMMR could be used to predict outcomes and identify patients with TNBC who may benefit from immunotherapy.

Autops Case Rep, vol.11, e2021253, 2021