Clinical and Histological Basis of Adenosquamous Carcinoma of the Pancreas: A 30-year Experience

A narrative review on rare types of pancreatic cancer: should they be treated as pancreatic ductal adenocarcinomas?

Pancreatic cancer is one of the deadliest malignancies in humans and it is expected to play a bigger part in cancer burden in the years to come. Pancreatic ductal adenocarcinoma (PDAC) represents 85% of all primary pancreatic malignancies. Recently, much attention has been given to PDAC, with significant advances in the understanding of the mechanisms underpinning disease initiation and progression, along with noticeable improvements in overall survival in both localized and metastatic settings. However, given their rarity, rare histological subtypes of pancreatic cancer have been underappreciated and are frequently treated as PDAC, even though they might present non-overlapping molecular alterations and clinical behavior. While some of these rare histological subtypes are true variants of PDAC that should be treated likewise, others represent separate clinicopathological entities, warranting a different therapeutic approach. In this review, we highlight clinical, pathological, and molecular aspects of rare histological types of pancreatic cancer, along with the currently available data to guide treatment decisions.

PD-L1 expression in pancreaticobiliary adenosquamous carcinoma: a single-institution case series

Background

The programmed cell death protein 1 (PD-1)/programmed cell death ligand 1 (PD-L1) pathway is a potent negative regulator of T-cell-mediated immune response that is upregulated in many neoplasms. Pancreaticobiliary adenosquamous carcinoma (PB-ASC) is an aggressive cancer that carries a poorer prognosis compared with pure pancreaticobiliary adenocarcinoma (PB-AC). To date, there is little published information regarding PD-L1 expression in PB-ASC. The aim of the study was to examine the relationship between PD-L1 expression and tumor-infiltrating lymphocytes in PB-ASC and PB-AC.

Methods

We evaluated 15 PB-ASCs (10 pancreatic, 5 gallbladder) and 34 control PB-ACs (22 pancreatic ductal, and 12 gallbladder) for tumor expression of PD-L1 using anti-PD-L1 (E1L3N) antibody. All tumors were classified into three immune phenotypes: immune inflamed (II), immune excluded (IE), and immune desert (ID) according to the distribution of tumor-infiltrating lymphocytes in tumor tissues.

Results

The frequency of PD-L1 expression was significantly higher in PB-ASC (10/15; 66.7%) than in PB-AC (3/34; 8.8%). In PB-ASC, PD-L1 expression occurred exclusively in the squamous component in six cases, exclusively in the glandular component in one case, and in both the squamous and the glandular components in three cases. PD-L1 expression in PB-ASC was irrespective of the tumor immune status, whereas its expression in PB-AC was observed only in tumors with the II or IE phenotype. The ID phenotype was relatively rare (4/15; 26.7%) in PB-ASC compared with PB-AC (22/34; 65%; P=0.02).

Conclusions

PB-ASCs are notably enriched in inflammatory response and showed significantly higher PD-L1 expression than PB-AC (P<0.001), suggesting a potential therapeutic role for immune checkpoint inhibitors in managing patients with PB-ASC.

A case of pancreatic adenosquamous cell carcinoma with a pseudocyst following curative surgery

BACKGROUND

Pancreatic adenosquamous cell carcinoma (PASC) is a relatively rare histological type of pancreatic malignancy, and preoperative diagnosis is difficult because of its rarity. PASC accounts for 1-4% of all pancreatic cancers, and even after curative surgery, its prognosis is poorer than that of ordinary pancreatic adenocarcinoma. Pathologically, it shows glandular and squamous differentiation of cells. Complete resection is the only method to achieve a good long-term prognosis, and an increasing doubling time of PASC is considered to indicate early recurrence after surgery. Here, we report a rare case of PASC with an infected pancreatic cyst that was difficult to treat, along with a review of the literature.

CASE PRESENTATION

A woman in her 80s with a history of breast cancer presented with pericardial pain. Computed tomography revealed a 20-mm hypovascular tumor in the body of the pancreas and a 27-mm pseudocyst. Endoscopic retrograde cholangiopancreatography showed a severe main pancreatic duct stenosis in the body of the pancreas that made cannulation impossible, and contrast media extravasation was due to pancreatic duct disruption in the pancreatic tail. Endoscopic fine-needle aspiration revealed that the tumor was a PASC. Because the patient had an infected pancreatic cyst, central intravenous nutrition and antibiotics were administered, which stabilized her general condition. She was diagnosed with resectable PASC and underwent distal pancreatectomy with lymphadenectomy. The postoperative course was uneventful. Immunohistochemical analysis of the resected specimen confirmed T2N0M0 stage IB. Systemic adjuvant chemotherapy with S-1 is ongoing.

CONCLUSION

Appropriate preoperative management and preoperative accurate staging (T2N0M0 stage IB) of PASC with curative surgery can ensure predictable outcomes.

The Importance of Reading the Skin: Cutaneous Metastases of Pancreatic Cancer, a Systematic Review

BACKGROUND

Pancreatic cancer is notorious for its aggressive nature and low survival rate, with less than 10% of patients surviving beyond five years. Early detection is difficult, but skin metastases can be a rare but significant indicator. This systematic review focuses on the epidemiology, clinical features, and histology of skin metastases from pancreatic cancer to determine their importance in early diagnosis and overall management of the disease.

MATERIALS AND METHODS

Following PRISMA guidelines, we conducted an exhaustive search of MEDLINE/PubMed, EMBASE, and SCOPUS databases up to June 2023, using specific keywords. Four independent investigators screened the studies using predefined criteria, and two investigators checked the accuracy and consistency of the data extraction. We assessed the quality of the trials using adapted criteria from the Joanna Briggs Institute. A narrative synthesis rather than a meta-analysis was chosen because of the different study designs.

RESULTS

The final analysis included 57 patients with skin metastases from pancreatic cancer. Cutaneous metastases, although rare, presented with approximately equal gender distribution and a mean age of 63.4 years. Predominantly non-umbilical (77%), these metastases showed clinical diversity, ranging from asymptomatic nodules to painful or ulcerated lesions. Notably, skin metastases often preceded the diagnosis of primary pancreatic cancer (58%). Primary tumor characteristics revealed different localizations, with adenocarcinoma being the most prevalent histological type (77%). A significant association (p = 0.008) was observed between pancreatic tumor location and the timing of presentation of skin metastases. Tumors located in the body and tail of the pancreas were more likely to manifest skin metastases as an initial clinical manifestation (62.2%) than those in the head of the pancreas (20.8%).

CONCLUSIONS

In conclusion, although skin metastases are rare, they are important indicators of pancreatic cancer, highlighting the need for multidisciplinary healthcare collaboration and thorough skin examination. Recognizing them could lead to earlier diagnosis, which is crucial in a cancer with limited treatment options.

Genomic landscape and clinical features of rare subtypes of pancreatic cancer: analysis with the national database of Japan

BACKGROUND

Special subtypes of pancreatic cancer, such as acinar cell carcinoma (ACC), adenosquamous carcinoma (ASC), and anaplastic carcinoma of the pancreas (ACP), are rare, and so data on them are limited. Using the C-CAT database, we analyzed clinical and genomic characteristics of patients with these and evaluated differences on comparison with pancreatic ductal adenocarcinoma (PDAC) patients.

METHODS

We retrospectively reviewed data on 2691 patients with unresectable pancreatic cancer: ACC, ASC, ACP, and PDAC, entered into C-CAT from June 2019 to December 2021. The clinical features, MSI/TMB status, genomic alterations, overall response rate (ORR), disease control rate (DCR), and time to treatment failure (TTF) on receiving FOLFIRINOX (FFX) or GEM + nab-PTX (GnP) therapy as first-line treatment were evaluated.

RESULTS

Numbers of patients with ACC, ASC, ACP, and PDAC were 44 (1.6%), 54 (2.0%), 25 (0.9%), and 2,568 (95.4%), respectively. KRAS and TP53 mutations were prevalent in ASC, ACP, and PDAC (90.7/85.2, 76.0/68.0, and 85.1/69.1%, respectively), while their rates were both significantly lower in ACC (13.6/15.9%, respectively). Conversely, the rate of homologous recombination-related (HRR) genes, including ATM and BRCA1/2, was significantly higher in ACC (11.4/15.9%) than PDAC (2.5/3.7%). In ASC and ACP, no significant differences in ORR, DCR, or TTF between FFX and GnP were noted, while ACC patients showed a trend toward higher ORR with FFX than GnP (61.5 vs. 23.5%, p = 0.06) and significantly more favorable TTF (median 42.3 vs. 21.0 weeks, respectively, p = 0.004).

CONCLUSIONS

ACC clearly harbors different genomics compared with PDAC, possibly accounting for differences in treatment efficacy.

Partial response in non-resectable adenosquamous carcinoma of the pancreas with high tumour mutation burden treated with gemcitabine, nab-paclitaxel and pembrolizumab

A previously healthy man in his 60s was diagnosed with a rare histological subtype of pancreatic cancer, adenosquamous carcinoma. After somatic mutation profiling, it was found that the tumour had microsatellite instability status high and a high tumour mutational burden. The patient was started on combination therapy with gemcitabine, nab-paclitaxel and pembrolizumab. Tumour size and biomarkers showed a dramatic response eventually leading to the patient being transitioned to maintenance therapy with pembrolizumab. The patient has demonstrated continued response since the start of the treatment. This is the first report in the literature showing a sustained response in this type of neoplasm that was treated with a checkpoint inhibitor, and thus adds to the evidence supporting universal somatic testing in all pancreatic cancers for a tailored approach to therapy.

Research advances and treatment perspectives of pancreatic adenosquamous carcinoma

BACKGROUND

As a malignant tumor, pancreatic cancer has an extremely low overall 5-year survival rate. Pancreatic adenosquamous carcinoma (PASC), a rare pancreatic malignancy, owns clinical presentation similar to pancreatic ductal adenocarcinoma (PDAC), which is the most prevalent pancreatic cancer subtype. PASC is generally defined as a pancreatic tumor consisting mainly of adenocarcinoma tissue and squamous carcinoma tissue. Compared with PDAC, PASC has a higher metastatic potential and worse prognosis, and lacks of effective treatment options to date. However, the pathogenesis and treatment of PASC are not yet clear and are accompanied with difficulties.

CONCLUSION

The present paper systematically summarizes the possible pathogenesis, diagnosis methods, and further suggests potential new treatment directions through reviewing research results of PASC, including the clinical manifestations, pathological manifestation, the original hypothesis of squamous carcinoma and the potential regulatory mechanism. In short, the present paper provides a systematic review of the research progress and new ideas for the development mechanism and treatment of PASC.

Pancreatic Adenosquamous Carcinoma: A Rare Pathological Subtype of Pancreatic Cancer

Pancreatic adenosquamous carcinoma (PASC) is a rare pathological subtype of pancreatic cancer (PC), with a worse prognosis than pancreatic ductal adenocarcinoma (PDAC). Due to its rarity, our knowledge of PASC and its biological characteristics are limited. In this review, we provide an overview of the histogenesis, genetic features, diagnosis, treatment, and prognosis of PASC, as well as pancreatic squamous cell carcinoma (PSCC). The information provided here may help to clarify our understanding of PASC and provide useful avenues for further research on this disease.

Delayed local recurrence of pancreatic adenosquamous cell carcinoma after curative surgery: A case report

Introduction

Pancreatic adenosquamous cell carcinoma (PASC) is a rare histological type of pancreatic malignancy with a particularly poor prognosis, even after curative surgery. Here, we describe the long-term prognosis of PASC in a patient who developed delayed local recurrence of the remnant pancreas after successful distal pancreatectomy, together with a literature review.

Presentation of case

A 59-year-old woman had a history of hepatitis C. Computed tomography revealed a hypointense mass in the pancreatic body in the arterial phase of the study. Magnetic resonance imaging revealed a tumor (20 mm) in the pancreatic body and dilatation of the main pancreatic duct at the periphery of the tumor. The patient was diagnosed with resectable pancreatic ductal adenocarcinoma and underwent distal pancreatectomy with lymphadenectomy; her postoperative course was uneventful. Immunohistochemical analysis of the resected specimen confirmed the diagnosis of tumor node metastasis [TNM] classification T2N1M0 stage IIB. Five years after curative surgery, following adjuvant systemic chemotherapy with S-1, local recurrence in the remnant pancreas occurred, which invaded the common hepatic artery and celiac pleural plexus. Systemic chemotherapy with gemcitabine and abraxiane is currently underway.

Discussion

Curative surgery significantly affects the prognosis of patients with PASC. Adjuvant chemotherapy may prolong the survival of these patients. Delayed remnant pancreatic recurrence should be considered during the surveillance of pancreatic cancer after curative resection.

Conclusion

We present a case of PASC in a patient who developed local recurrence in the remnant pancreas 5 years after successful distal pancreatectomy. Special attention should be paid not only to early recurrence but also to delayed local recurrence in PASC.

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Pancreatic adenosquamous cell carcinoma (PASC) is a rare histological type of pancreatic malignancy

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We describe the long-term prognosis of PASC in a patient who developed delayed local recurrence of the remnant pancreas after distal pancreatectomy.

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Delayed remnant pancreatic recurrence should be considered during the surveillance of pancreatic cancer after curative resection.

Survival Analysis and Prediction Model of ASCP Based on SEER Database

Background

This study aims to compare the incidence and clinical and survival characteristics of adenosquamous carcinoma of the pancreas (ASCP) and adenomatous carcinoma of the pancreas (ACP), analyze the survival factors of ASCP and construct a prognostic model.

Method

Patients diagnosed with pancreatic cancer from 2000 to 2018 are selected from the SEER database. ASCP and ACP are compared in terms of epidemiology, clinical characteristics and prognosis. Cases are matched in a 1:2 ratio, and survival analysis is performed. The Cox proportional hazard model is used to determine covariates related to overall survival (OS), and an ASCP prognosis nomogram is constructed and verified by consistency index (C-index), calibration chart and decision curve analysis (DCA). The accuracy of the model is compared with that of AJCC.Stage and SEER.Stage to obtain the area under the receiver operating characteristic (ROC) curve.

Results

the age-adjusted incidence of ACP increased significantly over time from 2000 to 2008 and from 2008 to 2018 (P < 0.05). APC was 2.01% (95% CI: 1.95–2.21) and 1.08% (95% CI: 0.93–1.25) respectively. The age-adjusted incidence of ASCP increased with time from 2000 to 2018 (P < 0.05) and APC was 3.64% (95% CI: 3.25–4.01).After propensity score matching (PSM), the OS and cancer-specific survival (CSS) of ACP are better than those of ASCP. The survival time of ASCP is significantly improved by the combined treatment of surgery + chemotherapy + radiotherapy, with a median OS of 31 months. Cox proportional hazard regression analysis shows that age, race, surgery, radiotherapy, chemotherapy and tumor size are independent factors affecting the prognosis. DCA and area under the curve (AUC) value shows that the model has good discrimination ability.

Conclusion

The OS prognosis of ASCP is worse than that of ACP, and the nomogram has high accuracy for the prognosis prediction of ASCP.

A phase II trial of the super-enhancer inhibitor Minnelide™ in advanced refractory adenosquamous carcinoma of the pancreas

Adenosquamous carcinoma of the pancreas (ASCP) is a very rare and highly aggressive variant of pancreatic ductal adenocarcinoma, accounting for 0.5-4% of all pancreatic cancer cases in the USA. Current data indicate that epigenetic changes and MYC overexpression lead to squamous transdifferentiation of pancreatic tumor cells and development of ASCP. Minnelide™, an oral anti-super-enhancer drug that inhibits MYC expression in preclinical models of ASCP, has demonstrated safety in a phase I study. We describe the design for a phase II, open-label, single-arm trial of Minnelide in patients with advanced refractory ASCP.

Humeral metastases: an unusual presentation of pancreatic cancer

In patients presenting with symptomatic bone metastases, the usual primary malignancies are breast, prostate, thyroid, lung and kidney. Pancreatic cancers are an uncommon cause of bone metastasis and, when they are, it is typically to the axial skeleton. We present the case of a 77-year-old woman who presented to our emergency department with right arm pain. Investigation demonstrated a metastatic lesion with impending pathological fracture. Further investigation found a necrotic pancreatic mass in the tail of the pancreas. Histopathology from the humeral metastasis was consistent with metastatic adenosquamous carcinoma of pancreatic origin. The humerus metastasis was successfully managed with an intramedullary nail. This case highlights an unusual presentation of pancreatic adenocarcinoma with humeral bone metastasis.

Adenosquamous cancer of the pancreas: A multicenter retrospective study

INTRODUCTION

Adenosquamous cancer of the pancreas (ASCP) is an aggressive, infrequent subtype of pancreatic cancer that combines a glandular and squamous component and is associated with poor survival.

METHODS

Multicenter retrospective observational study carried out at three Spanish hospitals. The study period was: January 2010- August 2020. A descriptive analysis of the data was performed, as well as an analysis of global and disease-free survival using the Kaplan-Meier statistic.

RESULTS

Of a total of 668 pancreatic cancers treated surgically, twelve were ASCP (1.8%). Patient mean age was 69.2±7.4 years. Male/female ratio was 1:1. The main symptom was jaundice (seven patients). Correct preoperative diagnosis was obtained in only two patients. Nine pancreatoduodenectomies and three distal pancreatectosplenectomies were performed. 25% had major complications. Mean tumor size was 48.6±19.4 mm. Nine patients received adjuvant chemotherapy. Median survival time was 5.9 months, and median disease-free survival was 4.6 months. 90% of patients presented recurrence. Ten of the twelve patients in the study (83.3%) died, with disease progression being the cause in eight. Of the two surviving patients, one is disease-free and the other has liver metastases.

CONCLUSION

ASCP is a very rare pancreatic tumor with aggressive behavior. It is rarely diagnosed preoperatively. The best treatment, if feasible, is surgery followed by the standard chemotherapy regimens for pancreatic adenocarcinoma.

Benign vs malignant pancreatic lesions: Molecular insights to an ongoing debate

Several benign conditions such as chronic pancreatitis, autoimmune pancreatitis, and paraduodenal pancreatitis can present as mass lesions and may mimic pancreatic ductal adenocarcinoma (PDAC) clinically and radiologically. Thorough histologic examination with attention to certain morphologic features can assist in deciphering neoplastic from reactive, however small biopsies often remain a challenge. Variable histologic patterns in conventional PDAC may also confound the diagnosis of PDAC. Uncommon subtypes of pancreatic carcinoma such as adenosquamous and squamous cell carcinoma, colloid carcinoma, medullary carcinoma, hepatoid carcinoma and signet ring cell carcinoma necessitate excluding metastasis from other sites prior to rendering the diagnosis of pancreatic carcinoma. The use of immunohistochemical staining and molecular markers can aid in separating benign from malignant and PDAC from metastasis. PDAC expresses a few non-specific epithelial and mucin immunomarkers such as CK7, CK19, MUC1, MUC4 and MUC5AC. However, the only immunohistochemical marker that is specific for PDAC in the right clinical context is SMAD4. Loss of SMAD4 within atypical glands and ducts supports the diagnosis of PDAC in a limited sample. Unfortunately, this finding is seen only in 50% of PDAC cases. The identification of certain mutations can help support a diagnosis of PDAC when benign conditions are in the differential. At the molecular level, KRAS oncogene mutations are seen in approximately 93% of PDACs. Subsequent neoplastic progression is driven by additional mutations of tumor suppressor genes, such as CDKN2A, TP53, and SMAD4. Molecular markers can also provide an insight to the prognosis. For instance, the loss of SMAD4 is associated with a poor outcome whereas mutations in MLL, MLL2, MLL3, and ARID1A are associated with improved survival.