Neuroendocrine carcinomas of the pancreas with 'Rhabdoid' features

HER-2-positive primary neuroendocrine neoplasms of the breast with signet ring feature: A case report and review of literature

Background

Primary neuroendocrine neoplasm of the breast (BNEN) is an uncommon breast neoplasm, and in most cases, it presents as hormone receptors positive and HER-2 negative. Moreover, in neuroendocrine neoplasms (NENs), the signet ring feature is a rare morphological subtype, and only a few cases have been reported. Here, we report the case of a primary breast neuroendocrine neoplasm with an unusual signet ring cell appearance in this paper. The documentation of this case, combined with a review of the literature, may add to existing knowledge about the outcome and management of this rare tumor.

Methods

In the present review, we describe a unique case of HER-2-positive primary BNEN with a signet ring feature that has not been reported in English. Additionally, we performed a literature search of the PubMed and Web of Science databases and calculated statistics for clinical data and follow-up.

Results

Our literature search, excluding non-English literature, identified 15 articles with data from 24 cases, including ours. The mean age was 51.25 years (range, 30-79 years), and there were 13 male patients (54%) and 11 female patients (46%). Of the 24 cases, some cases (11/24) were associated with lymph node metastases, a few cases (6/24) had distant metastasis, and the vast majority of cases (23/24) occurred in the digestive system. Primary hepatic signet ring cell neuroendocrine tumor showed slow progression and good prognosis. Lymph node involvement was identified in one of eight (12.5%) documented cases, and one of eight (12.5%) reported cases presented with distant metastatic disease. However, the prognosis of neuroendocrine tumors with signet ring cells in the pancreas and stomach was poor. Lymph node involvement was identified in 9 of 15 (60%) documented cases, and 5 of 15 (33.3%) reported cases presented with distant metastatic disease.

Conclusion

NENs with a signet ring feature is uncommon, and this is the first case report of its occurrence in the breast. Current knowledge is limited to anecdotal experience based on case reports and small case series. We provide a literature review to summarize knowledge about this rare entity.

SWI/SNF Complex-deficient Undifferentiated Carcinoma of the Gastrointestinal Tract: Clinicopathologic Study of 30 Cases With an Emphasis on Variable Morphology, Immune Features, and the Prognostic Significance of Different SMARCA4 and SMARCA2 Subunit Deficiencies

Undifferentiated carcinoma of the gastrointestinal tract has variable rhabdoid features. Expression of switch/sucrose nonfermenting (SWI/SNF) complex subunits is reportedly lost in a portion of cases; however, the prognostic significance of this loss remains unknown. Herein, 30 undifferentiated carcinoma cases were assessed for the expression of 4 SWI/SNF complex subunits (SMARCB1, SMARCA2, SMARCA4, and ARID1A). Tumor origin sites comprised stomach (40.0%), large intestine (20.0%), small intestine (16.7%), lower esophagus and stomach fundus (13.3%), ileocecal junction (3.3%), rectum (3.3%), and pancreas (3.3%). The tumors were composed of epithelioid neoplastic cells arranged in diffuse solid or discohesive sheets, nests, cords, poor cohesive pseudoglandular, and trabecular patterns. Rhabdoid tumor cells were identified in 66.7% (20/30) of cases. In total, 29/30 (96.7%) showed complete loss of at least 1 SWI/SNF subunit: SMARCA4-/SMARCA2- (11), isolated SMARCA4- (2), SMARCA4-/SMARCA2 unknown (6), isolated SMARCA2- (7), SMARCA2-/ARID1A- (1), and isolated ARID1A- (2). Negative or decreased expression (≤10% positive) of pan-cytokeratin was observed in 58.6% (17/29) of cases. In addition, 66.7% (20/30) of patients were late-stage (III or IV), and 65.2% (15/23) of stage IIB to IV patients succumbed to the disease at a mean clinical follow-up of 12.7 months. Specifically, patients with loss of SMARCA4 expression had the worst overall survival (P=0.028) and disease-free survival (P=0.006) rates, compared with those with SMARCA4 expression. The loss or decreased expression of epithelial markers is thus common in SWI/SNF complex-deficient undifferentiated carcinoma of the gastrointestinal tract, and loss of SMARCA4 correlates with poor prognosis.

Reconsideration of Clinicopathologic Prognostic Factors in Pancreatic Neuroendocrine Tumors for Better Determination of Adverse Prognosis

The question of how successful we are in predicting pancreatic neuroendocrine tumors (panNET) with poor prognosis has not been fully answered yet. The aim of this study was to investigate the effects of clinicopathological features on prognosis and to determine their validity in prediction of prognosis and whether a better prognostic classification can be made. Fifty-six patients who underwent pancreatic resection for pancreatic neuroendocrine tumor were included. The associations between clinicopathological parameters and prognosis were evaluated statistically. Efficiencies of different thresholds for tumor size, mitotic count, and Ki67 proliferation index for prognosis prediction were compared. Vascular invasion was statistically associated with high tumor grade, advanced pT stage, and mortality rate. The presence of non-functional tumor, lymphatic invasion, and > 10 cm tumor size were significantly related to shorter overall survival. Advanced pT stage (pT3-4), > 5 cm tumor size, and high tumor grade (grades 2-3) were significantly associated with shorter disease-free survival. The mortality rate showed the strongest statistical significance with mitotic count when grouped as 1: < 2, 2: 2-10, and 3: > 10 mitosis/ 2 mm². The 10% threshold value for Ki67 index was more successful in predicting adverse prognosis. Among the morphologic variants, the ductulo-insular variant was the most promising to have positive prognostic value in our series, although no statistical significance was detected. In conclusion, threshold values of 5 cm and 10 cm for tumor size, 10% for Ki67 proliferation index, and 10/2 mm² for mitotic count and vascular and lymphatic invasion assessed separately are potential prognostic candidates for better stratification of panNETs.

Morphologic Variants of Pancreatic Neuroendocrine Tumors: Clinicopathologic Analysis and Prognostic Stratification

Better prognostication/stratification of pancreatic neuroendocrine tumors (PanNETs) is needed. In this detailed morpheomic study of 163 resected PanNETs, 11 unusual variants, some of which were not previously recognized, and others scarcely documented in the literature, were identified, and their pathologic characteristics were further analyzed. By behavior and clinicopathologic associations, these variants could be grouped into three prognostically different categories. I. More aggressive (20%). Included in this group were the variants that in average showed higher grade and stage and adverse outcome including oncocytic, plasmacytoid, lipid-rich and previously unrecognized hepatoid variants, which often had a more diffuse/broad-band growth pattern, with some also displaying discohesiveness. They were characterized by abundant cytoplasm and often had prominent nucleoli (as seen in metabolically active cells), thus the provisional name "metabolic cell phenotype." Because of their diversion from classical neuroendocrine cytomorphology, these variants created challenges on original diagnostic workup, particularly hepatoid examples, which revealed Arginase 1/Hep Par-1 expression in 50%. II. Less aggressive (10%). These cases either showed signs of maturation, including nested growth, paraganglioid pattern (which was previously unrecognized), and organoid PanNETs such as "ductulo-insular" growth, or showed symplastic/degenerative changes, and despite their paradoxically disconcerting histology, were more benevolent in behavior. III. Undetermined. There were other variants including mammary tubulolobular-like, pseudoglandular, peliotic, and sclerotic PanNETs, which although diagnostically challenging, their biologic significance could not be determined because of rarity or heterogeneous characteristics. Prognostic associations: Features that were significantly different in the more aggressive group than the less aggressive group were median size (5.0 vs 1.6 cm, p < 0.001), percentage of pT3+T4 cases (72% vs 12%, p < 0.001), Ki67 index (5.3% vs 2.3%, p = 0.001), % G2 and G3 cases (77% vs 27%, p < 0.001), and rate of lymph node and distant metastasis (96% vs 27%, p < 0.001). In stepwise logistic regression model using the 3 established prognosticators of T stage, size, and grade along with morphology, only aggressive-morphology (metabolic cell phenotype) was found to be associated with metastatic behavior with an odds ratio of 5.9 with 95% confidence interval (C.I.) 1.688 to 22.945 and p value 0.007. In conclusion, PanNETs display various morphologic patterns that are not only challenging and important diagnostically but appear to have biologic significance. Tumors with more diffuse growth of cells with nucleoli and abundant cytoplasm and/or discohesion (oncocytic, hepatoid, lipid-rich, plasmacytoid PanNETs), provisionally termed "metabolic cell phenotype," show aggressive characteristics and are an independent determinant of adverse outcome and thus may require closer post-surgical follow-up, whereas variants with more degenerative or mature features (ductuloinsular, pleomorphic, paraganglioma-like) appear to be more benevolent despite their more atypical and worrisome morphology.

Neuroendocrine tumor of the pancreas with rhabdoid feature

Imaging of a 53-year-old Japanese man revealed two tumors in the liver and a tumor in the head of the pancreas with a swelling lymph node. A needle biopsy for the liver tumors was performed, revealing a neuroendocrine tumor. Enucleation, lymphadenectomy, and partial hepatectomy were performed. The microscopic examination identified many tumor cells with intracytoplasmic inclusions arranged in a nested, cord, or tubular fashion. The intracytoplasmic inclusions displayed densely eosinophilic globules and displaced the nuclei toward the periphery, which constitutes “rhabdoid” features. The tumor cells were positive for synaptophysin and weakly positive for NCAM, but negative for chromogranin A. Epithelial markers (AE1/AE3 and CAM5.2) accentuated intracytoplasmic globules. Pancreatic neuroendocrine tumors with rhabdoid features are very rare. Generally, rhabdoid features are aggressive and dedifferentiated characteristics of various types of tumor. Pancreatic neuroendocrine tumors containing rhabdoid cells tend to display extrapancreatic spread at the time of presentation, although some of these tumors with rhabdoid features are not always associated with aggressive behavior.

Clinicopathological characteristics of anaplastic carcinoma of the pancreas with rhabdoid features

Undifferentiated (anaplastic) carcinoma with rhabdoid features is a rare and aggressive subtype of pancreatic carcinoma. Here, we report the clinical, histological, and immunohistochemical phenotypes in six autopsy cases of anaplastic carcinoma with rhabdoid features. The patients ranged between 44 and 76 years of age (median, 61 years) and consisted of four males and two females. All patients except one case died within 3 months of diagnosis, as these tumors were found at an advanced stage and were chemoresistant. At autopsy, tumor masses measuring 4-22 cm in maximum diameter were mainly located in the pancreatic body and tail. Microscopically, all cases showed anaplastic carcinoma with rhabdoid features that were discohesive with round to polygonal eosinophilic cytoplasm with occasional inclusions, and that had vesicular nuclei, and prominent nucleoli. Immunohistochemistry showed that the rhabdoid cells, particularly the inclusions, were strongly positive for pan-cytokeratin (AE1/AE3) and vimentin. Meanwhile, downregulation or aberrant cytoplasmic localization with focal aggregation of E-cadherin, β-catenin, and EMA were frequently observed in the rhabdoid cells. Moreover, the intracytoplasmic inclusions were labeled with selective autophagy-related molecules including p62/SQSTM1, ubiquitin, and kelch-like ECH-associated protein 1 (KEAP1). In addition, nuclear factor erythroid 2-related factor 2 (NRF2) and overexpression of its target molecule multidrug resistance-associated protein 1 (MRP1) were commonly observed in the rhabdoid cells. Therefore, these results suggest that p62-mediated aggregation of ubiquitinated intermediate filaments and membranous proteins is an important phenomenon in the rhabdoid phenotype. Indeed, the ubiquitinated aggregates of p62 and KEAP1 would induce activation of NRF2 and upregulation of MRP1, leading to potential chemoresistance of anaplastic carcinoma with rhabdoid features.

Neuroendocrine tumors of the pancreas: current concepts and controversies

In the past decade, the clinico-pathologic characteristics of neuroendocrine tumors (NETs) in the pancreas have been further elucidated. Previously termed "islet cell tumors/carcinomas" or "endocrine neoplasms", they are now called pancreatic NETs (PanNETs). They occur in relatively younger patients and may arise anywhere in the pancreas. Some are associated with von Hippel-Lindau, MEN1, and other syndromes. It is now widely recognized that, with the exception of tumorlets (minute incipient neoplasms) that occur in some syndromes like MEN1, all PanNETs are malignant, albeit low-grade, and although they have a protracted clinical course and overall 10-year survival of 60-70 %, even low-stage and low-grade examples may recur and/or metastasize on long-term follow-up. Per recent consensus guidelines adopted by both European and North American NET Societies (ENETS and NANETs) and WHO-2010, PanNETs are now graded and staged separately, unlike previous classification schemes that used a combination of grade, stage, and adjunct prognosticators in an attempt to define "benign behavior" or "malignant" categories. For staging, the ENETs proposal may be more applicable than CAP/AJCC, which is based on the staging of exocrine tumors. Current grading of PanNETs is based on mitotic activity and ki-67 index. Other promising prognosticators such as necrosis, CK19, c-kit, and others are still under investigation. It has also been recognized that PanNETs have a rather wide morphologic repertoire including oncocytic, pleomorphic, ductulo-insular, sclerosing, and lipid-rich variants. Most PanNETs are diagnosed by fine needle aspiration biopsy, in which single, monotonous plasmacytoid cells with fair amounts of cytoplasm and distinctive neuroendocrine chromatin are diagnostic. Molecular alterations of PanNETs are also very different than that of ductal or acinar tumors. Loss of expression of DAXX and ATRX proteins has been recently identified in 45 %. Along with these improvements, several controversies remain, including grading, value of current cutoff ranges, and the best methods for counting ki-67 index (manual count by computer-captured image may be the most practical for the time being). More important is the controversial use of the term "carcinoma", which was previously employed in WHO-2004 only for invasive and metastatic cases but has now been made synonymous with grade 3 group of tumors. It is becoming clear that grade 3 group comprises two distinct categories: (1) differentiated but proliferatively more active tumors which typically have ki-67 indices in the 20-50 % range and (2) true poorly differentiated NE carcinomas as defined in the lung, with ki-67 typically >50 %. Further studies are needed to address these controversial aspects of PanNETs.

Pancreatic endocrine neoplasms: a current update on genetics and imaging

Pancreatic endocrine neoplasms are rare pancreatic tumours that may occur sporadically or as part of inherited syndromes such as multiple endocrine neoplasia-1 syndrome, von Recklinghausen disease, von Hippel-Lindau syndrome and tuberous sclerosis complex. Recent advances in the genetics and pathology of hereditary syndromes have provided valuable insights into the pathophysiology and biology of sporadic pancreatic endocrine neoplasms. Evolving molecular data on the biology of these neoplasms have the potential for diagnostic, therapeutic and prognostic use.

Endocrine tumours of the pancreas

Verbeke C S (2010) Histopathology 56, 669-682 Endocrine tumours of the pancreas Histopathology reporting of pancreatic endocrine neoplasms is complex. The tumours can exhibit a variety of morphological appearances, which often require careful differential diagnostic consideration. Prediction of tumour behaviour and clinical outcome is based on the World Health Organization classification and TNM staging and grading system, which share some criteria and premises, but differ significantly in others. Clinicopathological correlation through discussion at multidisciplinary team meetings is of paramount importance. In this review special emphasis is given to the items of information that can and should be provided by the pathologist to allow optimal patient management. The review further discusses areas of current controversy and uncertainty, of which pathologists participating in multidisciplinary discussions should be aware.

Endocrine neoplasms of the pancreas: pathologic and genetic features

CONTEXT

Pancreatic endocrine neoplasms (PENs) are diagnostically challenging tumors whose natural history is largely unknown. Histopathology allows the distinction of 2 categories: poorly differentiated high-grade carcinomas and well-differentiated neoplasms. The latter include more than 90% of PENs whose clinical behavior varies from indolent to malignant and cannot be predicted by their morphology.

OBJECTIVES

To review the literature and report on additional primary material about the clinicopathologic features, classification, staging, grading, and genetic features of PENs.

DATA SOURCES

Literature review of relevant articles indexed in PubMed (US National Library of Medicine) and primary material from the authors' institution.

CONCLUSIONS

The diagnosis of PEN is generally easy, but unusual features may induce misdiagnosis. Immunohistochemistry solves the issue, provided that the possibility of a PEN has been considered. Morphology allows the distinction of poorly differentiated aggressive carcinomas from well-differentiated neoplasms. The World Health Organization classification criteria allow for the discernment of the latter into neoplasms and carcinomas with either benign or uncertain behavior. The recently proposed staging and grading systems hold great promise for permitting a stratification of carcinomas into clinically significant risk categories. To date, inactivation of the MEN1 gene remains the only ascertained genetic event involved in PEN genesis. It is inactivated in roughly one-third of PENs. The degree of genomic instability correlates with the aggressiveness of the neoplasm. Gene silencing by promoter methylation has been advocated, but a formal demonstration of the involvement of specific genes is still lacking. Expression profiling studies are furnishing valuable lists of mRNAs and noncoding RNAs that may advance further the research to discover novel markers and/or therapeutic targets.

Changing incidence of pancreatic neoplasms: a 16-year review of statewide tumor registry

OBJECTIVES

Although most pancreatic neoplasms are adenocarcinoma, there are many other histological types, some of which may be increasing in frequency. To better define these trends, we reviewed 16 years of data from a statewide tumor registry.

METHODS

Using the State of Michigan tumor registry, all patients with primary pancreatic cancers from 1986 to 2002 were identified, and patients were excluded if there were insufficient data or the histological subtype was not clearly defined in the literature.

RESULTS

There were 17,610 pancreatic neoplasms identified, and 2425 were excluded, leaving a final population of 15,185. Twenty-five types of primary pancreatic neoplasms were identified. The most common were adenocarcinoma, mucinous cystadenocarcinoma, nonfunctional neuroendocrine, adenosquamous, anaplastic, intraductal papillary mucinous, and acinar cell (8.37, 0.43, 0.18, 0.05, 0.04, 0.04, and 0.02 per 100,000 per year, respectively). The mean age at presentation was similar for tumor types, 69.2 years old, with the exception of endocrine neoplasms occurring at a younger age, 58.5 years old (P < 0.0005). There was a significant change in the incidence of nonfunctional neuroendocrine neoplasms, greater than 2-fold increase (P = 0.0003).

CONCLUSIONS

The incidence of most pancreatic neoplasms has changed a little; however, nonfunctional neuroendocrine neoplasms increased greater than 2-fold. The etiology of this change is unclear.

Endocrine pancreatic tumors: diagnosis and treatment

Endocrine pancreatic tumors (EPTs) are uncommon, having an incidence of one per 100,000 people. They may appear as sporadic tumors or be associated with hereditary syndromes. EPTs are categorized as functioning or nonfunctioning tumors, based on the presence or absence of clinical syndromes. Among the former, insulinomas and gastrinomas are the most common. For the histopathological investigation of EPTs, chromogranin A and synaptophysin immunostainings are recommended. Measurement of circulating chromogranin A is also the cornerstone for the biochemical diagnosis of these tumors. Furthermore, specific hormones produced and released by the neoplastic cells can be identified by immunostaining and used for biochemical evaluation. To locate EPTs, both noninvasive (ultrasonography, computerized tomography, MRI and radionuclear imaging) and invasive techniques (arterial stimulation with venous sampling) can be used. Debulking procedures (surgery, radiofrequency ablation, embolization/chemoembolization and liver transplantation) and/or medical treatment (chemotherapy, biotherapy and peptide receptor radionuclide therapy) are the options available for the treatment of EPTs. Understanding the molecular events underlying the pathobiology of EPTs will aid the development of more accurate diagnostic/prognostic markers and give guidance for improved therapeutic modalities.

Anaplastic carcinoma of the pancreas with rhabdoid features and hyaline globule-like structures

A 59-year-old Japanese man presented with a giant submucosal tumor with ulceration during follow-up of duodenal ulcer. Pancreaticoduodenectomy was undertaken, and subsequent histological examination of the tumor disclosed anaplastic carcinoma of the pancreas head. The carcinoma components contained adenocarcinoma and squamous cell carcinoma. Additionally, undifferentiated spindle or pleomorphic cells were seen in continuity with the carcinoma component. Undifferentiated neoplastic cells with rhabdoid features and with hyaline globule-like structures positive for PAS stain with diastase pretreatment were also observed. Immunohistochemically, cytoplasmic inclusions corresponding to rhabdoid features showed aggregates of vimentin. Ultrastructurally, hyaline globule-like structures corresponded to lysosomes. Finally, we report here the first case of anaplastic carcinoma of the pancreas with hyaline globule-like structures.

Histologic variants of papillary and follicular carcinomas associated with anaplastic spindle and giant cell carcinomas of the thyroid: an analysis of rhabdoid and thyroglobulin inclusions

We describe the histologic variants of papillary and follicular carcinomas associated with 109 spindle and giant cell carcinomas (SGCC) of the thyroid and determine the incidence of rhabdoid and thyroglobulin inclusions in these tumors. In addition, we searched for rhabdoid and thyroglobulin inclusions in 120 papillary carcinomas (PC) (all 15 variants included), 23 differentiated follicular carcinomas (DFC), (6 with insular pattern), 6 poorly differentiated follicular carcinomas (PDFC) and 34 follicular adenomas (FA). The following differentiated thyroid carcinomas coexisted with SGCC: 51 (46.8%) PC, (34 conventional type, 14 tall cell variant and 3 follicular variant), 6 (5.5%) DFC, 1 follicular carcinoma with insular pattern (0.9%), and 3 oncocytic carcinomas (2.8%). Eleven SGCC (10%) and 2 (33%) PDFC showed rhabdoid features, but lacked thyroglobulin inclusions. Thyroglobulin inclusions were found in 10 FA (29%), 8 (17%) follicular variants of PC and in 7 (30.4%) DFC. There were no rhabdoid inclusions in any of these differentiated thyroid tumors. Our findings support the hypothesis that most SGCC result from dedifferentiation or anaplastic transformation although the mechanisms that underlie this transformation remain unknown. The finding that only 1 (0.9%) SGCC was associated with follicular carcinoma with insular pattern contradicts the opinion that this tumor occupies an intermediate position between differentiated and anaplastic carcinomas. Rhabdoid features are markers of PDFC and SGCC while thyroglobulin inclusions are markers of FA and differentiated thyroid carcinomas with follicular phenotype.

Renal cell carcinoma with rhabdoid features: an aggressive neoplasm with overexpression of p53

CONTEXT

Adult renal cell carcinoma (RCC) with rhabdoid features is a recently recognized morphologic variant of kidney carcinoma. To date, only very few studies have been published on this subject and p53 was not previously studied.

OBJECTIVE

To evaluate clinical attributes, morphology, and immunohistochemistry in RCC with rhabdoid component.

DESIGN

Reviewing a consecutive series of 310 RCCs, we identified 14 cases of RCC with rhabdoid features. All cases were reviewed and subjected to detailed clinical and pathologic studies with immunohistochemical evaluation of p53.

RESULTS

All tumors were clear RCCs with rhabdoid component representing from 5% to 50% of the tumor volume. Rhabdoid cells were large with a central eosinophilic intracytoplasmic inclusion and an eccentric atypical nucleus. Tumor necrosis was common (13/14) and sometimes extensive. Nine of 14 tumors were staged pT3, 4 of 14 were pT2, and only 1 tumor was pT1. On immunohistochemistry, rhabdoid cells were positive for vimentin (14/ 14), epithelial membrane antigen (11/14), and cytokeratin (9/14). Desmin and smooth muscle actin were always negative. p53 was positive in 10 of 14 tumors in the rhabdoid areas (5%-50% of tumor cells stained) but only in 5 of 14 cases in usual clear renal cell areas. In the follow-up, 10 of 14 patients developed metastases and 6 of 14 died of the disease. The median of survival was 8 months.

CONCLUSIONS

We showed that RCC with rhabdoid features is a very aggressive neoplasm with a poor prognosis. We observed an overexpression of p53 in the rhabdoid component that may be implicated in the tumor dedifferentiation.

SMARCB1/INI1 missense mutation in mucinous carcinoma with rhabdoid features

Malignant rhabdoid tumor (MRT) is a rare and aggressive tumor associated with deletion or mutation of a tumor suppressor gene SMARCB1/INI1, a member of the SWI/SNF chromatin-remodeling complex. Reported herein is a case of pancreatic mucinous carcinoma accompanying rhabdoid features with immunohistochemical and ultrastructural studies as well as analysis of the SMARCB1/INI1 gene. A 65-year-old woman presented with a 2 month history of abdominal and chest pain. A well-defined grayish tan fish-flesh mass (11 x 9 x 7 cm) with focal mucinous area was present in the pancreatic tail. Microscopically, the tumor had a biphasic growth pattern: a mucinous carcinoma component and a poorly differentiated carcinoma component with rhabdoid features showing loosely cohesive cells with abundant eosinophilic cytoplasm, displaced nuclei, and prominent nucleoli. The rhabdoid component coexpressed vimentin and cytokeratin. Sequencing analysis of the DNA extracted from the mucinous and rhabdoid components showed a missense mutation CCC to ACC in codon 116 of the SMARCB1/INI1 gene. Being aware of rhabdoid features would help diagnose this rare and aggressive malignant tumor and may provide an opportunity for further evaluation of SMARCB1/INI1 gene alteration and determination of its prognostic significance.

Update on pancreatic endocrine tumors

Endocrine tumors of the pancreas represent 1% to 2% of all pancreatic neoplasms. The tumors tend to have an indolent behavior, and long-term survival is common. There is no gender or age predilection. Patients can present with symptoms due to hormonal excess or a local mass effect or be asymptomatic. The tumors tend to be solid and well circumscribed. Typical microscopic findings include an organoid pattern of growth, with cells containing scant to moderate amounts of cytoplasm, and nuclei with dispersed chromatin and inconspicuous nucleoli. The morphologic spectrum of these tumors can be variable, and the differential diagnosis includes chronic pancreatitis with neuroendocrine hyperplasia, ductal adenocarcinoma, solid pseudopapillary tumor, acinar cell carcinoma, and pancreatoblastoma. The classification of these tumors remains controversial, and prognosis is difficult to predict, but important features include metastasis and invasion of adjacent structures. Resection remains the mainstay of surgical treatment. It is important to be aware that unusual morphologic variants of pancreatic endocrine tumors are common, and immunohistochemical stains can help avoid misdiagnosis.

Pleomorphic pancreatic endocrine neoplasms: a variant commonly confused with adenocarcinoma

Most pancreatic endocrine neoplasms (PENs) have distinctive endocrine growth patterns and uniform nuclear morphology; they are regarded as relatively low-grade tumors. Significant nuclear pleomorphism is a feature that may raise concerns about aggressive behavior or even obscure the endocrine nature of the neoplasm. Eight PENs exhibiting marked nuclear pleomorphism (>20% of the tumor cells) were identified during a review of 136 PENs (5.9%) from the pathology files of Memorial Sloan-Kettering Cancer Center. The histologic, immunohistochemical, ultrastructural (4 cases), and clinical features were reviewed. There were 6 males and 2 females ranging from 30 to 69 years (mean, 55 years). The tumors averaged 5.8 cm (range, 1.5-14 cm). Six tumors (75%) were initially misdiagnosed in 5 cases as adenocarcinoma and in one as solid-pseudopapillary tumor; in 2 cases, the misdiagnosis was based on fine needle aspiration cytology and in 4 on histologic examination. The architectural features of the tumors resembled those of other PENs, but the nuclei were markedly enlarged, irregularly shaped, and hyperchromatic, with frequent bizarre forms. Cells with pleomorphic nuclei also generally had abundant cytoplasm, sometimes with large perinuclear glassy inclusions. The mitotic rate was not elevated compared with other PENs, averaging 1.9 (range, 0-7) per 50 high power fields. Immunohistochemical findings were (number positive/number stained): chromogranin (8 of 8), synaptophysin (7 of 8), progesterone receptor (4 of 7), CD99 (2 of 5), S-100 protein (3 of 7), and p53 (0 of 6). Scattered cells expressed peptide hormones in a minority of cases. By electron microscopy, abundant dense core granules were identified, in some cases embedded within perinuclear arrays of intermediate filaments. Six patients underwent curative resection; at follow-up, 4 were free of disease at 11, 13, 30, 112 months (mean, 42 months), 1 developed liver metastases at 77 months and was alive with disease at 94 months, and 1 was lost to follow-up. Two patients had unresectable tumors and were alive with disease at 10 and 78 months. Striking nuclear pleomorphism may occur in otherwise typical PENs and commonly causes difficulties in the distinction from adenocarcinoma. There does not appear to be prognostic significance to these nuclear changes, and the morphologic features of pleomorphic PENs otherwise resemble those of their conventional counterparts.

Pancreatic endocrine tumour with cytoplasmic keratin whorls. Is the term "rhabdoid" appropriate?

A 50 year old woman presented with acute abdominal pain accompanied by nausea and vomiting and was found to have a mass in the head of the pancreas by imaging. The clinical impression was of a pancreatic carcinoma and a Whipple's procedure was performed. Microscopic examination of the tumour showed it to be a low grade neuroendocrine carcinoma arranged in a tubuloacinar or tubulopapillary pattern, and composed of cells harbouring very prominent intracytoplasmic inclusions. These inclusions varied in appearance from being pale pink and hyaline in quality to more eosinophilic and globular causing displacement of the nucleus. Ultrastructural examination showed typical paranuclear aggregates of intermediate filaments. Inclusions of this type have been described previously as "signet ring like" and "rhabdoid". It was felt that the inclusions more closely resemble the fibrous bodies that are seen in pituitary adenomas. In addition, it is suggested that both signet ring and rhabdoid are not appropriate because they do not reflect histogenesis and are not necessarily reflective of tumour biology. It is suggested that the term "cytokeratin aggresomes" should be used to describe this distinctive phenotype.