UNASSIGNED: Large cell neuroendocrine carcinomas of the colon (LCNECC) are exceptionally rare, comprising only 0.2 % of all colonic carcinomas. Their diagnosis poses a significant challenge due to their propensity to mimic colonic adenocarcinomas. Typically diagnosed at advanced stages, LCNECCs carry a grim prognosis. Herein, we present a rare case of LCNECC and aim to elucidate its clinico-pathological characteristics.
METHODS: A 56-year-old female patient presented with complaints of constipation, abdominal pain, and weight loss. On physical examination, a sizable mass was palpable in the right flank. Colonoscopy revealed a polyp in the descending colon and a friable multinodular stenosing mass in the ascending colon. Microscopic examination of the biopsy from the ascending colon mass exhibited a poorly differentiated large cell carcinomatous proliferation with positivity for synaptophysin and CD56, along with a Ki-67 proliferation index of 50 %. The polyp in the descending colon was consistent with a low-grade dysplastic tubular adenoma. A diagnosis of LCNECC with synchronous low-grade dysplastic tubular adenoma was established. A right hemicoloctomy was performed. Final pathological examination confirmed LCNECC invading the muscularis propria, with lymph node metastases. The tumor was classified as pT2N1M0 (Stage III).
UNASSIGNED: LCNECCs often mimic adenocarcinomas clinically, endoscopically, and radiologically. Pathological examination is the key for diagnosis. An immunohistochemical study using neuroendocrine markers is imperative to prevent overlooking the diagnosis of LCNECC.
CONCLUSIONS: LCNECCs represent rare aggressive carcinomas. Their diagnosis might be challenging. A better knowledge of this rare entities would enable early diagnosis.

BACKGROUND: Herein we report a case of an extremely rare pancreatic adenocarcinoma with enteroblastic differentiation (AED), an underrecognized histological subtype. Moreover, the tumor was mixed with a neuroendocrine carcinoma (NEC), which is also a rare malignancy in the pancreas.
METHODS: The patient was an elderly male who was incidentally diagnosed with a 35 mm-sized pancreatic head tumor and underwent pancreatoduodenectomy. Histopathologically, the tumor was composed of four different types: conventional ductal adenocarcinoma, AED, NEC, and squamous cell carcinoma. Interestingly, p53 overexpression and loss of Rb expression, which are characteristic findings of NEC, were observed in all components. He had been received adjuvant chemotherapy after the surgery, however, he died of bath-related cardiac arrest 14 months after surgery.
CONCLUSIONS: In the stomach, AED, a carcinoma resembling fetal gut epithelium, is a rare but established subtype and is considered a related entity of hepatoid carcinoma (HAC). However, gastric AED and HAC differ to some extent. In contrast to the stomach, extragastric AED, including pancreatic AED, is extremely rare, and its biological features are unclear. A mixed tumor with NEC is a complex phenomenon, but it is occasionally reported in extragastric AED. The histogenesis of mixed AED-NEC can be resolved by determining p53 and Rb status.
CONCLUSIONS: Owing to their rare and novel nature, extragastric AED is under-recognized or confused with HAC. Further studies and the establishment of an extragastric AED classification are required.

BACKGROUND: Neuroendocrine carcinoma (NEC) of the extrahepatic bile duct is very rare, and the treatment and prognosis are unclear. Herein, we report the case of a middle-aged female with primary large cell NEC (LCNEC) of the common hepatic duct combined with distal cholangiocarcinoma (dCCA). Additionally, after a review of the relevant literature, we summarize and compare mixed neuroendocrine-non-neuroendocrine neoplasm (MiNEN) and pure NEC to provide a reference for selecting the appropriate treatment and predicting the prognosis of this rare disease.
METHODS: A 62-year-old female presented to the hospital due to recurrent abdominal pain for 2 months. Physical examination showed mild tenderness in the upper abdomen and a positive Courvoisier sign. Blood tests showed elevated liver transaminase and carbohydrate antigen 199 levels. Imaging examination revealed a 1-cm tumour in the middle and lower segments of the common bile duct. Pancreaticoduodenectomy + lymph node dissection was performed, and hepatic duct tumours were unexpectedly found during surgery. Pathology suggested poorly differentiated LCNEC (approximately 0.5 cm × 0.5 cm × 0.4 cm), Ki-67 (50%), synaptophysin+, and chromogranin A+. dCCA pathology suggested moderately differentiated adenocarcinoma. The patient eventually developed lymph node metastasis in the liver, bone, peritoneum, and abdominal cavity and died 24 months after surgery. Gene sequencing methods were used to compare gene mutations in the two primary bile duct tumours.
CONCLUSIONS: The prognosis of MiNEN and pure NEC alone is different, and the selection of treatment options needs to be differentiated.

Neuroendocrine prostate neoplasms, encompassing small cell carcinoma, carcinoid, and large cell carcinoma, are infrequently observed in malignant prostate tumors. The occurrence of large cell neuroendocrine prostate cancer (LCNEPC) is exceedingly rare. In this study, the patient initially presented with a persistent dysuria for a duration of one year, accompanied by a serum prostate-specific antigen (PSA) level of 17.83ng/mL. Prostate magnetic resonance imaging (MRI) and chest computed tomography (CT) scan showed that a neoplastic lesion was considered, and prostate biopsy confirmed prostate adenocarcinoma with a Gleason score of 7 (4 + 3). Then, thoracoscopic lung tumor resection was performed, and the pathological examination revealed the presence of primary moderately differentiated invasive adenocarcinoma of the lung and metastatic prostate adenocarcinoma, the Gleason score was 8 (4 + 4). After 1 year of endocrine therapy with goserelin acetate and bicalutamide, he underwent a laparoscopic radical prostatectomy (LRP), the pathological report indicated the presence of adenocarcinoma mixed with NE carcinoma. Two months after the LRP, the patient experienced gross hematuria and sacral tail pain. Further examination revealed multiple metastatic lesions throughout the body. He also underwent transurethral resection of bladder tumor (TURBT) for bladder tumor and received etoposide+ cisplatin chemotherapy three weeks post-surgery. The patient eventually died of multi-organ failure due to myelosuppression after chemotherapy. This case report presents an uncommon instance of LCNEPC with widespread systemic metastases, while also providing a comprehensive review of existing literature to facilitate improved management and treatment strategies for similar patients in subsequent cases.

A 52-year-old woman presented to our hospital with chief complaints of upper abdominal bloating and lower leg edema. Computed tomography (CT) revealed liver metastasis from a gallbladder tumor. This tumor was diagnosed as neuroendocrine carcinoma (NEC) on performing a biopsy. Physical examination revealed a moon face. Blood tests revealed hypokalemia and high levels of adrenocorticotropic hormone (ACTH) and cortisol. Dexamethasone suppression test revealed that cortisol secretion was not suppressed, and the patient was diagnosed with gallbladder NEC and ectopic ACTH syndrome (EAS). Metyrapone was administered to suppress cortisol production; however, she developed septic shock due to cellulitis in the lower leg and died on the 16th day of admission. A pathological autopsy was performed, which revealed disseminated intravascular coagulation and acute respiratory distress syndrome as the cause of death. Only a few cases of EAS due to NEC originating from the gallbladder have been reported. The patient reported here succumbed shortly after diagnosis, thereby highlighting the challenges in treating gallbladder NEC complicated by EAS.

UNASSIGNED: Laryngeal neuroendocrine carcinomas are the most common non-squamous neoplasm of the larynx. Due to the rarity of the tumor, pathological diagnosis should be confirmed by immunohistochemistry.
UNASSIGNED: Laryngeal neuroendocrine carcinomas (LNECs) are a rare cancer of the head and neck. Few case reports of poorly differentiated neuroendocrine carcinoma originating in the subglottic larynx exist within the literature. In this case, we discuss a 57-year-old patient with a history of four-month hoarseness with a newly diagnosed of poorly differentiated neuroendocrine carcinoma in the subglottic larynx. Treatment and prognosis of the various NEC groups differ, so precise identification requires consideration of the microscopic findings and immunostaining analysis. immunohistochemistry staining demonstrated positive result for cytokeratin 7, synaptophysin, chromogranin, CD 56, with the Ki-67 index of45%. Although surgery is usually the treatment for all tumor types, chemo radiotherapy is recommended for poorly differentiated NECs because surgery is ineffective.

Small-cell carcinoma of the bladder (SCCB) is an uncommon and aggressive malignancy of the urinary tract. Its clinical presentation often mimics that of other bladder neoplasms, posing a diagnostic challenge. This case report presents a rare instance of SCCB in a 65-year-old female, shedding light on the diagnostic journey and emphasizing the need for heightened and prompt clinical suspicion due to its aggressive nature. The patient presented to the urological department with hematuria, dysuria, and hypogastric pain. Initial investigations revealed a bladder mass, prompting biopsies with inconclusive results. A comprehensive histopathological examination, including immunohistochemistry, confirmed a SCCB. A computed tomography (CT) scan was used to evaluate local and distal extention. Following the initial evaluation, a referral to an oncological service was needed. Diagnoses encompassed SCCB, with interventions that comprise chemotherapy without radical cystectomy. Despite the rarity of SCCB, timely and accurate diagnosis facilitated a tailored multidisciplinary approach, leading to prompt clinical oncology management. This case demonstrates the importance of meticulous diagnostic evaluation in rare malignancies, guiding individualized therapeutic strategies for optimal patient outcomes.

Squamous cell carcinoma is the most predominant type of malignancy in the head and neck region with neuroendocrine carcinomas (NECs) being a rare occurrence. Here we report a rare case of small cell non-keratinizing NEC (WHO grade 3), TNM (tumor, node, and metastasis) stage T3N1M0, involving the larynx and the base of the tongue, in a 54-year-old male patient, demonstrating its rarity in an uncommon anatomical site and an aggressive and relatively uncommon pattern of spread for this tumor, over a period of two months. NECs in the head and neck region, especially those affecting the larynx and the posterior third of the tongue, remain exceedingly rare, comprising only a small fraction of malignancies in this region. The aggressive nature and distinct pattern of spread observed in this case underscore the importance of recognizing such unusual presentations for appropriate diagnosis and management. Given the rarity of this tumor type, a comprehensive understanding of its clinicopathological features is essential for guiding effective treatment strategies. We also discuss the treatment.

BACKGROUND: Early adenocarcinoma mixed with a neuroendocrine carcinoma (NEC) component arising in the gastroesophageal junctional (GEJ) region is rare and even rarer in young patients. Here, we report such a case in a 29-year-old Chinese man.
METHODS: This patient presented to our hospital with a 3-mo history of dysphagia and regurgitation. Upper endoscopy revealed an elevated nodule in the distal esophagus 1.6 cm above the GEJ line, without Barrett\'s esophagus or involvement of the gastric cardia. The nodule was completely resected by endoscopic submucosal dissection (ESD). Pathological examination confirmed diagnosis of intramucosal adenocarcinoma mixed with an NEC component, measuring 1.5 cm. Immunohistochemically, both adenocarcinoma and NEC components were positive for P53 with a Ki67 index of 90%; NEC was positive for synaptophysin and chromogranin. Next-generation sequencing of 196 genes demonstrated a novel germline mutation of the ERCC3 gene in the DNA repair pathway and a germline mutation of the RNF43 gene, a common gastric cancer driver gene, in addition to pathogenic somatic mutations in P53 and CHEK2 genes. The patient was alive without evidence of the disease 36 mo after ESD.
CONCLUSIONS: Early adenocarcinoma with an NEC component arising in the distal esophageal side of the GEJ region showed evidence of gastric origin.

Mixed neuroendocrine-non-neuroendocrine neoplasms (MiNENs) are rare tumors recently characterized by the presence of both neuroendocrine and non-neuroendocrine components within the same tumor tissue. Although MiNEN found their place in the WHO classification for various organs, this composite tumor in the head and neck region remains exceptionally rare. We present a case of primary oral MiNEN in a 64-year-old male located on the left side of lower gingiva. Biopsy raised suspicion of neuroendocrine carcinoma (NEC) and the patient underwent partial mandibulectomy. The resected specimen showed two distinct components of NEC and squamous cell carcinoma (SCC) with the confirmation of immunohistochemical markers. There has been no sign of recurrence nor metastasis 6 years after the surgery. In addition, we have conducted a review of published cases with potential relevance to this entity, resulting in five cases. The diverse terminology reinforces the need for a standardized classification system of oral/head and neck MiNENs.