Low Malignant Potential Research Articles

Central pancreatectomy (CP) offers parenchymal preservation compared to conventional distal pancreato-splenectomy for pancreatic neck and body tumours. However, it is associated with more morbidity. This study is aimed at evaluating the peri-operative and long-term functional outcomes, comparing central and distal pancreatectomies (DPs). Retrospective analysis of patients undergoing pancreatic resections for low-grade malignant or benign tumours in pancreatic neck and body was performed (from January 2007 to December 2022). Preoperative imaging was reviewed for all cases, and only patients with uninvolved pancreatic tail, whereby a CP was feasible, were included. Peri-operative outcomes and long-term functional outcomes were compared between CP and DP. One hundred twenty-two (5.2%) patients, amongst the total of 2304 pancreatic resections, underwent central or distal pancreatectomy for low-grade malignant or benign tumours. CP was feasible in 55 cases, of which 23 (42%) actually underwent CP and the remaining 32 (58%) underwent DP. CP group had a significantly longer operative time [370min (IQR 300-480) versus 300min (IQR 240-360); p = 0.002]; however, the major morbidity (43.5% versus 37.5%; p = 0.655) and median hospital stay (10 versus 11days; p = 0.312) were comparable. The long-term endocrine functional outcome was favourable for the CP group [endocrine insufficiency rate was 13.6% in central versus 42.8% in distal (p = 0.046)]. Central pancreatectomy offers better long-term endocrine function without any increased morbidity in low malignant potential or benign pancreatic tumours of neck and body region.

TFE3-rearranged renal cell carcinomas (RCCs) harbor gene fusions between TFE3 and 1 of many partner genes. MED15::TFE3 fusion RCC is rare, often cystic, and easily misdiagnosed. This study aimed to characterize 2 cases of MED15::TFE3 fusion RCC with extensive cystic change using fluorescence in situ hybridization and targeted RNA sequencing. Both patients were young adult women aged 29 and 35 years. Radiologically, both presented with a cystic Bosniak category II renal lesion. The cysts measured 9.3 cm and 4.8 cm in greatest dimension. Both patients underwent cyst enucleation, and neither had tumor recurrence or metastasis at 26 and 6 months of follow-up, respectively. Microscopically, both tumors were entirely cystic, with thick, fibrous cystic walls lined by small clusters of cells with clear to eosinophilic cytoplasm and uniform, round nuclei with inconspicuous nucleoli. There were also small aggregations of similar clear cells within the cystic walls. Foci of basement membrane-like material depositions were noted in 1 case; calcifications were observed in both cases. Both cases demonstrated nuclear positivity for PAX8 and TFE3 and cytoplasmic staining for Melan-A; HMB45, CAIX, and CK7 were negative. Fluorescence in situ hybridization revealed that both tumors were positive for TFE3 rearrangements. RNA sequencing identified MED15::TFE3 gene fusions in both cases. The main differential diagnosis of MED15::TFE3 fusion RCC includes multilocular cystic renal neoplasm of low malignant potential and atypical renal cysts. Molecular confirmation of TFE3 fusion is essential for establishing the correct diagnosis.

The effect of androgens on the risk of endometriosis sub-phenotypes and ovarian neoplasms: A Mendelian randomization study

Introduction and importance: Bednar tumor, a rare variant of dermatofibrosarcoma protuberans is a tumor with low malignant potential. Owing to limited studies, the pathogenesis and risk factor of this tumor are not clearly understood. The tumor extends from the epidermis to the dermal layers and even affects the surrounding bone. Here, the authors present a case of a 48-year-old male with a Bednar tumor, which was successfully managed by wide local excision and flap repair. Case presentation: Our patient presented to the hospital after the reappearance of mass, 6 years after the excision of the previously misdiagnosed lipoma. Vitals and systematic examination were normal. Local examination revealed an oval-shaped mass with a glistening surface on the right shoulder. The patient underwent wide excision and skin flap surgery for the treatment, and the diagnosis was confirmed through histopathological examination and immunohistochemistry for the CD34 marker. Clinical discussion: Bednar tumor is an infrequent skin tumor linked to genetic anomalies and is one of the rare variants [(<0.1%) of skin tumors]. Diagnosis can be done by histopathological examination and CD34 marker positivity via immunohistochemistry. This tumor is mistaken for lipoma, leading to recurrent growth postexcision. The tumor demands a broader resection due to the high chances of reoccurrence. Although Mohs micrographic surgery is the ideal approach, its limited availability in resource-constrained settings prompts alternative strategies. Conclusion: This case highlights the challenges of diagnosis, the rarity of the condition, and the need for vigilant follow-up due to the tumor’s propensity for recurrence.

Aim: to discuss the clinical presentation, management, and outcome of the clinical case of solid pseudopapillary tumour of the pancreas (SPTP).Key points. SPTPs are rare tumours known for their low malignant potential. They are predominantly found in younger females, typically occurring in the tail of the pancreas. Surgical resection of SPTP with negative margins is associated with improved survival rates and lower chances of recurrence. In this study, we discuss the case of a 69-year-old woman diagnosed with an SPTP originating from the tail of the pancreas, which had spread to the hilum of the spleen. A radical resection was performed, successfully obtaining negative surgical margins. However, the patient subsequently developed metastasis to the liver and lungs, prompting the initiation of systemic chemotherapy. The patient died seven months after the development of metastasis and 39 months following the primary diagnosis. This case underscores that, despite initial successful surgical outcomes, high-risk histopathological features can lead to recurrence and metastasis, necessitating reassessment of treatment strategies.Conclusion. Negative surgical margins are critical for a favourable prognosis in the treatment of SPTPs; however, close monitoring for potential recurrence is essential. Our findings highlight that even after achieving negative margins, patients with high-risk features should undergo rigorous follow-up and consider postoperative systemic chemotherapy. This clinical case emphasizes the complexity of managing SPTP and the need for individualized treatment strategies, as early detection of recurrence can significantly influence survival outcomes.

Contrast-enhanced ultrasound (CEUS) is increasingly utilized for the noninvasive assessment of renal cystic lesions, using the Bosniak grading system. Bosniak 3-4 lesions require surgical referral, which allows correlation with the histopathological outcome. In this single-center, retrospective study we evaluated renal CEUS exams conducted with SonoVue® with a diagnosis of a Bosniak 3 or 4 lesion between 2019 and 2022. A total of 49 patients and 50 lesions met the inclusion criteria, 31 lesions had available histopathological results. Patient demographics, cyst morphology, and dominant imaging features were registered. The histopathological diagnosis was considered a reference standard. Positive predictive power (PPV) for neoplastic lesions was comparable in the Bosniak 3 and 4 categories (75 vs 93.3%, P = .33), while PPV for histopathologically malignant lesion was considerably higher in the latter group (25 vs 93.33%, P = .0002). None of the lesions which had vividly enhancing thin septa as their dominant CEUS feature were malignant. Oncocytoma, multilocular cystic renal neoplasm of low malignant potential, and cystic nephroma were the major benign entities among Bosniak 3 lesions. Localized cystic kidney disease and hemorrhagic cysts were found to be the primary mimickers leading to false positive imaging findings. CEUS has a high predictive power for malignancy in the Bosniak 4 category, which is not maintained in the Bosniak 3 group due to the large proportion of benign lesions. Adherence to rigorous rule-in criteria and active surveillance strategies need to be considered for equivocal CEUS Bosniak 3 lesions.

Abstract Introduction Solitary fibrous tumor (SFT) is a rare mesenchymal neoplasm usually located in the pleura and associated with NAB2-STAT6 gene fusion. According to the World Health Organization (WHO) classification, although most SFTs are considered well benign, some SFTs have cytological atypia, hypercellularity, tumor necrosis, Ki-67 greater than 5%, high mitotic rate (>4 per high-power field (HPF)) and/or the presence of infiltrative surgical margins are considered malignant. SFT with severe hypoglycemia is called Doege-Potter syndrome which occurs with ectopic secretion of a prohormone of insulin-like growth factor 2 (IGF-2) from tumor tissue. We present a case who applied with severe hypoglycemia and was diagnosed with a solitary fibrous tumor thought to originate from the adrenal gland located in the right retroperitoneal region. Clinical Case A 61-year-old female patient was admitted to the hospital after hypoglycemia was detected in her application due to clouding of consciousness. While the patient's glucose level was 23 mg/dL, insulin:0.4 µIU/mL, C-peptide:<0.01 ng/mL, serum cortisole: 24,20 (µg/mL), growth hormone (GH): 13,20 ng/ mL and insulin-like growth factor I (IGF-1) 38 ng/mL were measured. Insulinoma was excluded and because of IGF-2 level could not be measured in our hospital, low serum insulin and IGF-1 levels suggested high serum IGF-2 levels. HbA1c, adrenal gland, and pituitary function tests were normal (Table 1). A mass lesion of approximately 145×133 mm in size, with heterogeneous contrast, containing cystic areas, was seen, which was thought to originate from the right adrenal gland in the upper abdomen tomography taken due to the presence of a palpable abdominal mass on physical examination (Figure 1). Urine catecholamines were found to be normal, and the plasma aldosterone concentration (PAC)/plasma renin activity (PRA) ratio was 2.56. The patient was operated under intravenous infusion of 10% dextrose due to persistent hypoglycemia. The immunohistochemical evaluation showed CD34, SOX-1 and STAT6 positivity and negativity for S-100, HMB45, straight muscle actin, desmin, caldesmon and melan A, thus confirming the diagnosis of a solitary fibrous tumor. After the operation, the patient's hypoglycemia disappeared. Since there are cases in the literature in which Doege-Potter syndrome was diagnosed without measuring IGF-2, we think that our patient had IGF-2-related hypoglycemia. Conclusion The development of hypoglycemia in Doege-Potter syndrome has been associated with the secretion of large amounts of IGF-2 by tumor tissue, resulting in decreased IGF-1 and Insulin-like growth factor-binding protein 3 (IGFBP-3) concentrations. In these patients, the tumor originates from mesenchymal tumors of low malignant potential. In our case, the Ki-67 proliferation index was around 2%, it was considered benign, and the patient's symptoms completely regressed after resection.Figure 1.CT images of the patientA mass in the right retroperitoneal area, associated with the adrenal gland and containing areas of necrosis, is seen on non-contrast (a) and contrast-enhanced (b) CT scans. Table 1.Laboratory workup

Well-differentiated papillary mesothelial tumor (WDPMT) is a distinct form of mesothelioma with low malignant potential and is mostly found in the peritoneal cavity. It consists of mesothelial cells with papillary structure and bland cytology. We report a rare case of WDPMT with suspicious invasive foci in the tunica vaginalis. WDPMT with invasive foci is known to have a tendency for recurrence. Therefore, careful attention should be given to properly diagnosing and treating this rare entity.

Multilocular cystic renal cell carcinoma or multilocular clear cell renal cell carcinoma is a rare type of cystic neoplasms of kidney. MCRCC comprises 1-2% of all renal tumors. MCRCC has well defined diagnostic criteria, has low stage The term MCRCC was renamed as MCRNLMP by ISUP in 2013.Only few cases of MCRCC are reported in literature till now We report a rare case of MCRCC / MCRNLMP in 52 years female presented with chief complaints of pain and dragging sensation in the right side of abdomen for 1 year. Keywords: Multilocular, cystic, renal cell carcinoma, nephrectomy, low malignant potential

PurposeMucinous cystic neoplasms of the liver (MCN-L) are hepatic cysts with a low malignant potential. The recent European Association for the Study of the Liver (EASL) guidelines provide guidance on the imaging features and surgical management of MCN-L, yet are hampered by a lack of studies adhering to the revised World Health Organization (WHO) criteria. This study attempted to validate the new 2022 EASL-guidelines in a retrospective cohort study of patients who underwent surgery for suspected MCN-L.MethodsPatients undergoing surgery for suspected MCN-L in a single center between 2010 and 2020 were included. Imaging features were assessed according to the EASL guidelines and were compared to final pathological diagnoses, according to the WHO criteria.ResultsIn total, 35 patients were included. In three patients, there were no worrisome imaging features, yet final pathological diagnosis showed MCN-L. Contrarily, six patients with worrisome imaging features did not have MCN-L. Five patients were diagnosed with MCN-L on final pathology. The sensitivity of the EASL-guidelines for the diagnosis of MCN-L was 40% (95%CI: 5.3–85%) and the specificity was 80% (95% CI: 61–92%).ConclusionAlthough the new EASL-guidelines provide some guidance, they could not reliably distinguish MCN-L from other cysts in our series. Thus, preoperative diagnosis of MCN-L remains challenging and we should be careful in selecting surgical strategies based on these criteria.

Background: Surgical treatment is almost always necessary for lesions that cause stenosis or obstruction of the tracheobronchial system. Sleeve resection is a surgical method that ensures airway continuity and reduces the loss of lung tissue by creating a primary anastomosis following the resection of the affected segment. : In this study, 65 patients who underwent tracheobronchial sleeve resection and bronchoplasty at the Ankara Atatürk Sanatorium Training and Research Hospital between 1974 and 1997 were retrospectively evaluated. Patient data were obtained from medical records and surgical reports, and compared with the previous studies. Results: Of the 65 patients, 34 were male and 31 were female (mean age, 32.56 years; range, 5-65 years). Tracheal resection and reconstruction were performed in 25 patients because of stenosis and neoplasm, whereas bronchial sleeve resection and bronchoplasty were performed in 40 patients because of benign neoplasm, bronchial adenoma, bronchial carcinoma, endobronchial foreign body, and bronchial rupture. Conclusions: Resection of a small bronchial segment instead of pneumonectomy offers a curative treatment alternative for centrally localized, benign endobronchial lesions with low malignancy potential. In bronchial carcinomas, the results obtained from the complete removal of tumor tissue with sleeve lobectomy in a selected group of patients have shown that this surgical method may be an alternative to pneumonectomy. In patients with bronchial cancer, pneumonectomy should not be performed if sleeve lobectomy is possible. The high postoperative quality of life and low mortality and morbidity emphasize the superiority of this surgical method over pneumonectomy.

Parathyroid cancer is an uncommon endocrine malignancy. It has slow clinical course and low malignancy potential. It represents 1% of primary hyperparathyroidism. It results with more agrressive biological behaviour and severe clinical condition than benign reasons. Extended resection in the first operation is essential for PC treatment and decreases local recurrence that is observed in high frequency. Palliative surgery should be considered in patients with unresectable tumor. Immunotherapy and recent interventional radiological procedures are considered for patients that are unfit to surgery. Effect of adjuvant chemotherapy and radiotherapy is limited however recent immunization studies are promising. Parathyroid cancer epidemiology, staging system, diagnosis and advancements in treatment are considered according to recent literature in this review.

Introduction: There is a wide range of pathological lesions that can involve the urinary bladder, such as congenital anomalies, inflammatory conditions, metaplastic lesions and tumours which are responsible for significant morbidity and mortality worldwide. Broadly, bladder lesions are categorised as neoplastic and non neoplastic. Some urothelial lesions have mixed features or a tendency to transform into urothelial carcinoma such as metaplastic lesions, inverted papillomas, atypical papillary hyperplasia, Papillary Urothelial Neoplasm of Low Malignant Potential (PUNLMP) and urothelial dysplasia. They are grouped as grey zone lesions. Identifying the malignant nature of grey zone lesions is difficult to identify by histopathological examination. Pathologists are trying to differentiate and classify bladder tumours using Immunohistochemical (IHC) markers such as Cytokeratin (CK) 20, CK-7, p53, Ki-67, etc., to help oncologists take proper decisions regarding patient management. Aim: To study the histopathological lesions of urinary bladder tumours and diagnose the malignant nature of grey zone lesions using IHC marker CK 20. Materials and Methods: This cross-sectional study of urinary bladder lesions was conducted in the Department of Pathology of Subharti Medical College, Meerut, Uttar Pradesh, India between December 2012 and October 2014. A total of 87 patients with urological complaints were selected for the study. Data related to age, sex, clinical symptoms and personal habits were noted on a working proforma. Biopsy materials were processed and stained with Haematoxylin and Eosin (H&E) for histopathological examination. The intensity of the reaction was determined in different fields, ranging from negative (0) to intense (3). Data thus obtained were analysed and presented in this paper. Results: Out of 87 cases of urinary bladder lesions, 47 (54.02%) were neoplastic, 26 (29.88%) non neoplastic and 14 (16.09%) grey zone lesions. They were more common in males, particularly in the 7th and 6th decades of life, i.e., 27 (31.03%) and 22 (25.28%) respectively. The most common histopathological finding in non neoplastic lesions was inflammatory conditions seen in 21 (80.76%) cases; Papillary urothelial carcinoma-low- grade in 26 (55.31%) cases of neoplastic lesions and PUNLMP in 8 (57.14%) cases of grey zone lesions. The result was positive with CK 20 in 5 (62.5%) cases of PUNLMP, 1 (100%) urothelial dysplasia, and 1 (100%) poorly differentiated tumour tissues but negative in 3 (37.5%) cases of PUNLMP, 2 (100%) of Adenocarcinoma and 1 (100%) case of Nested Variant of Urothelial Carcinoma (NVUC). Conclusion: CK 20 is a good IHC marker for determining the malignant nature of tissues in grey zone lesions. The results will be more reliable when used together with other markers.

Uterine tumor resembling ovarian sex-cord tumor is a rare group of uterine neoplasms with unknown histogenesis and differentiation towards ovarian sex-cord elements. They are benign in nature with low malignancy potential. Diagnosis is based on immunohistochemistry and morphological features, and the distinction from other more malignant differentials is paramount to correctly individualizing treatment.

Introduction and objective: Renal cell carcinoma-(RCC) is the commonest renal malignancy, for which histomorphology remains important in determining the type. The aim of this study was to describe the RCC types encountered at a tertiary care delivery setting based on routine histomorphology and to identify potential cases requiring molecular analysis for further typing, as per the 5th WHO urinary and male genital tumours classification (Uro5).Methodology: Microscopy of all RCC cases reported at the Histopathology Departments of the National Hospital and Department of Pathology, Faculty of Medicine, University of Colombo, Sri Lanka from 2016 to 2020 were reviewed. Based on the most representative routine haematoxylin and eosin histomorphology, these were typed according to the WHO-Uro5. The tumours which need further molecular testing for typing were separated out.Results: A total of 228 RCC cases were reviewed. This included 189 clear cell RCC (82.9%), 24 papillary RCC (10.5%) and six chromophobe carcinomas (2.6%). One eosinophilic solid and cystic RCC (0.3%) and one multilocular cystic renal neoplasm of low-malignant potential (0.3%) were identified. Seven cases which possibly required molecular testing for tumour typing in addition to histomorphology were separated out (3.1%).Discussion and conclusion: With the introduction of targeted therapy, molecular profiling has significantly impacted the classification of adult renal malignancies, albeit histomorphology being the foundation of tumour taxonomy. The latest WHO–Uro5 has introduced a group of molecularly defined RCC entities. Therefore, it is worth facilitating molecular analysis to determine the RCC type as evidenced by this study (3.1%). The actual numbers of molecularly defined RCC types could even be higher, as some may mimic histomorphologically defined RCC types.

Neoplasms originating from the urachus are exceptionally uncommon, comprising only 0.17% of all bladder neoplasms. Among these, the mucinous cystic tumor of low malignant potential (MCTLMP) is particularly rare, with only 25 documented cases in medical literature. Despite their rarity, it is essential to identify MCTLMPs given the possibility of severe complications. Fortunately, surgical removal offers promising cure rates. In this report, A 40-year-old female patient presented to the hospital with abdominal pain. Subsequently, a CT scan showed a 9-cm cystic mass pressing the bladder. The lesion was surgically excised and histopathological examination was performed. Grossly, the specimen consisted of a cyst with a smooth external surface and mucinous content. Microscopically, the cyst was lined by columnar mucinous epithelial cells that included basally-located hyperchromatic nuclei and scattered Goblet cells consistent with an intestinal phenotype. The epithelial cells show mild atypia with focal papillary formations and flattening due to compression. Immunohistochemically, the epithelial tumor cells expressed cytokeratin 20, CDX2, beta-catenin (membranous); and were negative for cytokeratin 7. The location, histopathological, and immunohistochemical findings were consistent with a diagnosis of MCTLMP. In this report, we present an instance of urachal MCTLMP, which represents less than 30 cases documented in the medical literature. This case study marks the importance of early identification of MCTLMP due to their potential for severe complications, despite the tumor’s low malignant potential and to exclude more aggressive tumors with areas of intraepithelial or invasive carcinoma.

Bilateral adrenal pheochromocytoma (PCС) is extremely rare in children, with major predisposing factors being multiple endocrine neoplasia type 2 and von Hippel–Lindau syndrome. In case of bilateral PCC with underlying von Hippel–Lindau syndrome, organ-preserving surgery is preferred in view of the low malignant potential of such neoplasms. We aimed to study clinical and molecular genetic features of patients with bilateral adrenal PCCs treated at the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology, Ministry of Healthcare of the Russian Federation. The study was approved by the Independent Ethics Committee and the Scientific Council of the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology, Ministry of Healthcare of the Russian Federation. The study included 20 patients with paraganglioma (PGL)/PCC (PPGL) who had received treatment (n = 17) or outpatient care (n = 3) at the Center over the period from 2012 to 2023. Bilateral adrenal PCC was diagnosed in 4 (20%) patients. In all these cases, the diagnosis was confirmed by histology. Molecular genetic testing was carried out at the Laboratory of Molecular Biology at the Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology, Ministry of Healthcare of the Russian Federation in order to search for germline pathogenic variants in PCC/PGL susceptibility genes. The median age of the four patients with bilateral adrenal PCC was 9.5 years (range 4.5–14.6 years). All the patients were male. In one patient, synchronous bilateral PCC/PGL was observed. In 100% of the cases, arterial hypertension was diagnosed at the onset of the primary disease and was treated with alpha-blockers as part of preparation for surgery. According to the results of a 24-hour urine biochemistry test, all the patients had at least a 4-fold increase above the upper limit of normal for normetanephrine levels. Molecular genetic testing using the multiplex ligation-dependent probe amplification method revealed a pathogenic germline variant in exon 3 of the VHL gene in all the children (4/4). Hereditary PPGL was proven in 2/4 (50%) patients. In all the cases, R0/R1 resection was achieved. Organ-sparing surgery on one/two adrenal glands was performed in 3/4 cases. One out of four (25%) patients developed a local relapse 18.4 months after diagnosis. The overall survival rate in this group was 100%, with a median follow-up time of 8.1 months (range 0.8–50.2 months). Bilateral adrenal PCC is a very rare childhood tumor. A medical genetic consultation is necessary to identify tumor predisposition syndromes. A multidisciplinary team discussion of a surgical strategy is recommended, with organ-sparing surgery on one or two adrenal glands being the treatment of choice that should be carried out at centers specializing in pediatric surgical oncology. Here, we report a rare clinical case of bilateral retroperitoneal PCC/PGL in a patient with von Hippel-Lindau syndrome. The patient's parents gave consent to the use of their child's data, including photographs, for research purposes and in publications.

Objective: To investigate the gene mutation of telomerase reverse transcriptase (TERT) promoter in inverted urothelial lesions of the bladder and its significance in differential diagnosis. Methods: From March 2016 to February 2022, a total of 32 patients with inverted urothelial lesions diagnosed in Department of Pathology at Qingdao Chengyang People's Hospital and 24 patients at the Affiliated Hospital of Qingdao University were collected, including 7 cases of florid glandular cystitis, 13 cases of inverted urothelial papilloma, 8 cases of inverted urothelial neoplasm with low malignant potential, 17 cases of low-grade non-invasive inverted urothelial carcinoma, 5 cases of high-grade non-invasive inverted urothelial carcinoma, and 6 cases of nested subtype of urothelial carcinoma were retrospectively analyzed for their clinical data and histopathological features. TERT promoter mutations were analyzed by Sanger sequencing in all the cases. Results: No mutations in the TERT promoter were found in the florid glandular cystitis and inverted urothelial papilloma. The mutation rates of the TERT promoter in inverted urothelial neoplasm with low malignant potential, low grade non-invasive inverter urothelial carcinoma, high grade non-invasive inverted urothelial carcinoma and nested subtype urothelial carcinoma were 1/8, 8/17, 2/5 and 6/6, respectively. There was no significant difference in the mutation rate of TERT promoter among inverted urothelial neoplasm with low malignant potential, low-grade non-invasive inverted urothelial carcinoma, and high-grade non-invasive inverted urothelial carcinoma (P>0.05). All 6 cases of nested subtype of urothelial carcinoma were found to harbor the mutation, which was significantly different from inverted urothelial neoplasm with low malignant potential and non-invasive inverted urothelial carcinoma (P<0.05). In terms of mutation pattern, 13/17 of TERT promoter mutations were C228T, 4/17 were C250T. Conclusions: The morphology combined with TERT promoter mutation detection is helpful for the differential diagnosis of bladder non-invasive inverted urothelial lesions.

Solid pseudopapillary neoplasm of the pancreas (SPNP) is a rare primary neoplasm with distinct clinicopathological features. The tumor most commonly occurs inyounger (premenopausal) women and is typified by low malignant potential and an excellent overall prognosis. A retrospective search over 20 years at two referral tertiary care institutions (King Faisal Hospital and Research Center andKing Abdulaziz University Hospital, Jeddah, Kingdom of Saudi Arabia)revealed 12 female patients diagnosed with SPNPs. The reslts of ancillary studies performed at the time of diagnosis were also reviewed and placed in the context of current recommendations. The clinical and pathological findings were reviewed. All patients were females, aged 18 to 30 years. Eight patients presented with abdominal pain, of which two experienced significant weight loss, and four presented with abdominal mass/discomfort. The tumor size ranged from 1.5 and 15 cm. Two cases were initially diagnosed as neuroendocrine tumors (NETs). One of the cases presented as a multifocal disease. All patients were treated surgically with a follow-up period between one and 11 years. Only one patient presented with peritoneal metastasis after seven years of follow-up, but generally, all are doing well. We have analyzed 12 SPNP cases in our population over 20 years (2001-2021) in this study. In brief, SPNP is a low-grade malignant potential tumor. Even though SPNP is a recognized entity, diagnostic challenges can ariseparticularly in the setting of limited sampling.Pathologists must be aware of the classic morphological features of SPNP and the characteristic profile of immunohistochemistryand be able to differentiate SPNP from other mimickers, especially well-differentiated NETs of the pancreas, andultimately to avoid misdiagnosis and unnecessary oncologic treatment. Adequate surgical resection with negative margins is associated with an excellent outcome.

Introduction and importance: Cystic partially differentiated nephroblastoma (CPDN) is a rare cystic tumor that affects the kidney. It has a low potential for malignancy. It usually presents as an abdominal mass. It may be difficult to confirm the diagnosis of CPDN without a histopathological study. Case presentation: The authors report a case of an 18-month-old girl with abdominal distention, which was noticed by her parents. An abdominal computed tomography scan showed a large multilocular cystic mass arising from the lower pole of the left kidney. A left total nephrectomy was performed. Immature blastemal elements without evidence of malignant cells were observed on histological analysis. Conclusion: The authors report a case of an 18-month-old girl with CPDN managed by total nephrectomy. CPDN should be considered in the differential diagnosis of patients with cystic renal lesions. The authors would also like to affirm that partial or total nephrectomy should be done in all cases of CPDN and other cystic renal tumors.