Fluid Overload-Associated Large B-Cell Lymphoma: A Case Report and Review of Literature.

Fluid overload-associated large B-cell lymphoma (FO-LBCL) is a new entity described in the fifth edition of the World Health Organization (WHO) Classification of Hematolymphoid Tumors (WHO-HAEM5). It refers to malignant lymphoma present with symptoms of serous effusions in body cavities (pleural, peritoneal, and/or pericardial) in the absence of an identifiable tumor mass. We present a case of an 82-year-old man with a history of atrial fibrillation and atrial flutter, status post-ablation, essential hypertension (HTN), hyperlipidemia (HLD), and diabetes mellitus (DM) type 2 who was referred to our hospital for shortness of breath due to recurrent pleural effusion. Right video-assisted thoracoscopy with right pleural biopsy was performed. Histopathological examination of the pleural biopsy revealed dense fibrous tissue, chronic inflammation, lymphoid aggregates, and granulation tissue, with no evidence of lymphoma. Cytology of the right pleural fluid revealed large lymphoid cells, which were positive for CD45, CD20, PAX-5, MUM-1, BCL2, BCL6, and MYC protein. They were negative for CD3, CD10, CD138, and HHV-8 by immunohistochemistry (IHC). Epstein-Barr virus (EBV) was negative by in situ hybridization (ISH). Due to the absence of any evidence of lymphoma elsewhere, a diagnosis of fluid overload-associated large B-cell lymphoma (FO-LBCL) was made. We provide a synopsis of the main clinicopathological features of FO-LBCL and the two main differential diagnoses, primary effusion lymphoma (PEL) and diffuse large B-cell lymphoma (DLBCL).

Splenic Rupture Secondary to Amyloidosis: A Case Report and Review of the Literature.

Amyloidosis is a term describing the extracellular deposit of fibrils composed of subunits of several different normal serum proteins in various tissues. Amyloid light chain (AL) amyloidosis contains fibrils that are composed of fragments of monoclonal light chains. Many different disorders and conditions can lead to spontaneous splenic rupture, including AL amyloidosis. We present a case of a 64-year-old woman with spontaneous splenic rupture and hemorrhage. A final diagnosis of systemic amyloidosis secondary to plasma cell myeloma was made with infiltrative cardiomyopathy and possible diastolic congestive heart failure exacerbation. We also provide a narrative review of all documented cases of splenic rupture associated with amyloidosis from the year 2000 until January 2023, along with the main clinical findings and management strategies.

A study of somatic BRCA variants and their putative effect on protein properties in malignant mesothelioma.

Objectives: The aim of this study is to analyze the prevalence of somatic mutations in BRCA1 and BRCA2 in malignant mesothelioma and their putative impact on protein properties. Methods: Eighteen cases of malignant mesothelioma were retrieved from the archives and for next generation sequencing analysis of BRCA1 and BRCA2 genes. Variants were analyzed using Ensembl VEP17, Polyphen 2.0 software, SIFT software, MutpredV2, and SWISS-MODEL homology-modeling pipeline server. Results: BRCA2 variants were found in significantly higher percentage (22%) of cases (p=0.02). Five missense variants were identified. These were p.A2351P, p.T2250A, p.A895V, pG1771D, and p.R2034C. The SIFT scores of all except one were ≥ 0.03. The Polyphen scores of these four alterations were ≤0.899. In case of p.A2315, the SIFT score was 0.01, while the Polyphen 2 score was 0.921. MutPred2 scores were ≤0.180 for all. Loss of intrinsic disorder was predicted (Pr=0.32, p=0.07) for p.R2034C, while gain of intrinsic disorder was predicted for p.A2351P (Pr=0.36, p=0.01) and p.G1771D (Pr=0.34, p=0.02). Conclusions: BRCA2 somatic variants were identified in 22% cases of malignant mesotheliomas in this study. The variants localize more frequently to the disordered regions of the protein and are predicted to affect the level of disorder.

Prognostic Significance of p53 and p63 in Diffuse Large B-Cell Lymphoma: A Single-Institution Experience.

Diffuse large B-cell lymphoma (DLBCL) is the most common lymphoma in adults. We evaluated the immunohistochemical (IHC) expression of p63 and p53 in DLBCL and their significance on overall survival (OS) and progression-free survival (PFS). We conducted a retrospective cohort study of 177 patients with DLBCL who presented to Mount Sinai Medical Center of Florida (Miami Beach, Florida) between 2010 and 2020. IHC staining for p63 and p53 protein expression was performed. A significant correlation was found between p63 positivity and p53 expression, p53/p63 co-positivity, Ki-67 proliferation index, MYC expression, and MYC/BCL2 double expression. Regardless of the germinal center B-cell like (GCB) subgrouping, there was a trend among p53+ patients to have MYC/BCL2 double expression, positive MYC expression, and lower OS and PFS. A tendency of poor OS was seen in p53+ patients in the non-GCB, GCB, and double expressors subgroups and poor PFS in p53+ patients regardless of the subgrouping. In conclusion, our results suggest that p63 and p53 may represent potential additional prognostic biomarkers in DLBCL and may be included in the initial diagnostic work up of patients with DLBCL.

Hemophagocytic Lymphohistiocytosis in the Setting of Therapy-Induced Acute Myeloid Leukemia: An Autopsy Report.

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening hyper-inflammatory disorder that occurs due to immunologic dysregulation. HLH can be primary (hereditary) or secondary to infections, autoimmune diseases, immune deficiencies, metabolic diseases, drugs, or malignancies. Lymphoid neoplasms mostly accompany malignancy-associated HLH. We present a case of a 12-year-old boy with a history of precursor B lymphoblastic leukemia (B-ALL), who subsequently developed chemotherapy-induced acute myeloid leukemia (t-AML). The patient was admitted for febrile neutropenia and initial laboratory tests revealed hemophagocytic lymphohistiocytosis (HLH). The hospital course was complicated by multiple infections and septic shock. The patient received several broad-spectrum antimicrobials, dexamethasone, as well as a pericardial drain to drain the hemorrhagic pericardial effusion. Despite intervention, the patient expired, and an autopsy was performed. We provide a synopsis of the main autopsy findings.

MUM1/IRF4 is Highly Expressed in Dermatopathic Lymphadenopathy: Potential Utility in Diagnosis and Differential Diagnosis.

Dermatopathic lymphadenopathy (DL) is a distinctive type of lymph node hyperplasia that typically occurs in the setting of chronic dermatologic diseases. DL generally self-resolves following disappearance of the underlying skin stimulus and does not require any specific therapy. We recently observed multiple myeloma oncogene 1/interferon regulatory factor 4 (MUM1/IRF4) expression in a case of DL using immunohistochemical methods. The goal of this study was to systematically assess DL cases for MUM1/IRF4 expression and to survey other histiocytic and Langerhans cell lesions. We particularly focused on Langerhans cell histiocytosis (LCH) because the differential diagnosis of DL versus LCH in lymph nodes can be challenging. We identified high expression of MUM1/IRF4 in all 22 cases of DL tested. Specifically, MUM1/IRF4+ dendritic cells comprised 50% to 90% (median, 80%) of all dendritic cells in the paracortex of dermatopathic lymph nodes, always showing moderate or strong intensity. Among 10 DL cases stained for MUM1/IRF4 and langerin/CD207 using dual immunohistochemistry, MUM1/IRF4+ and langerin+ Langerhans cells represented 5% to 60% (median, 30%) of paracortical dendritic cells. MUM1/IRF4 was also positive in reactive Langerhans cells in skin biopsy specimens of all cases of spongiotic dermatitis (n=10) and normal skin (n=15), and was negative in all cases of LCH (n=24), Rosai-Dorfman disease (n=10), follicular dendritic cell sarcoma (n=5) and histiocytic sarcoma (n=4). In aggregate, our findings support the utility of MUM1/IRF4 to highlight the dendritic cells of DL and to distinguish DL from other histiocytic and Langerhans cells lesions.

ROS1 altered breast cancers - a distinctive molecular subtype of PR- metastatic breast cancers: Expanding the scope of targeted therapeutics.

BACKGROUND: Breast cancer, one of the leading causes of cancer-related mortality in women worldwide, exhibits wide-ranging histo-morphologic, clinical and molecular diversity. OBJECTIVE: This study compares the genetic alterations of breast tumors with the histo-morphological, hormone receptor status and metastatic "organotropism". MATERIALS AND METHODS: Twenty-two cases of primary invasive breast carcinoma with local/distant metastasis were retrieved from the pathology archives. The status of estrogen and progesterone receptors by immunohistochemistry was recorded along with other pertinent case data. Next generation sequencing was performed on formalin-fixed paraffin embedded blocks of tumor. RESULTS: The mean age of the study subjects was 57.9 ± 13.3 years. TP53 mutation was the most common gene alteration in this study and was seen in 40.9% cases. ROS1 gene was mutated in 44.4% PR negative breast cancers while being wild type in the twelve PR positive tumors. (p = 0.021).STRING interaction network constructed with ROS1 and PR revealed a significantly higher number of interactions in this network than expected (p-value 0.000973). CONCLUSION: This study highlights the significantly higher incidence of ROS1 gene alterations in metastatic PR- breast cancers, with STRING network analysis revealing higher nodal interaction in the nodal network comprised of PR and ROS1 exclusive of ER.

The mutational landscape of upper gastrointestinal adenocarcinomas- A study of similarities and differences.

PURPOSE: The gastrointestinal tract is home to a wide variety of neoplasms. Gastrointestinal adenocarcinomas display distinct prognostic patterns. With the advent of next generation sequencing, attempts are being made to delineate distinct molecular characteristics of these adenocarcinomas from adjoining anatomical sites. METHODS: Thirty-seven cases of upper gastrointestinal adenocarcinomas including those of the esophagus, gastroesophageal junction, stomach, small intestine and gallbladder were retrieved. Next generation sequencing data consisting of base substitutions, copy number variations, indels and rearrangements, in 324 genes, were analyzed for recurrent genetic abnormalities. Statistical analysis was performed using IBM SPSS25 and SAS software. RESULTS: Genetic alterations were found in 181 genes. APC mutations were found in 50% of the esophageal adenocarcinomas, 5% of the gastric adenocarcinomas and 33.3% of the small intestinal adenocarcinomas (p = 0.04). PIK3 gene family mutations were found in 10% of the gastric adenocarcinomas, 66% of the gall bladder adenocarcinomas and 66% of the small intestinal adenocarcinomas (p = 0.002). The mutations were found exclusively in the PIK3 class 1 family. TP53 mutations were more common in tumors with intact DNA mismatch repair protein expression as assessed by immunohistochemistry (p = 0.042). CONCLUSION: In this study, APC gene mutations were found to be more frequent in esophageal and small intestinal adenocarcinomas than previously reported. PIK3 class 1 gene family mutations were found to be more frequent in gallbladder and small intestinal adenocarcinomas. An inverse relationship was found between TP53 mutations and loss of DNA mismatch repair protein expression.

Cyclin D1 expression in Rosai-Dorfman disease: a near-constant finding that is not invariably associated with mitogen-activated protein kinase/extracellular signal-regulated kinase pathway activation.

Activating mutations in the mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) pathway have been shown in nearly half of the cases of Rosai-Dorfman disease (RDD). Cyclin D1, a key cell cycle regulator, constitutes a major downstream target of the MAPK/ERK pathway. In this study, we aim to further understand the pathogenesis of RDD by assessing the lesional histiocytes for cyclin D1, p-ERK, Ki-67, and BCL-2 by immunohistochemistry. We assessed 35 samples of RDD and a control group of histiocyte-rich reactive lesions. Cyclin D1 was expressed in about 90% of cases of RDD. Cyclin D1 was positive in 25-95% (median, 85%) of lesional histiocytes, was moderately/strongly expressed in 97% of cyclin D1-positive cases, and was significantly higher than in control specimens. p-ERK was positive in 16 of 30 (53%) cases of RDD and was negative in all controls. All p-ERK-positive RDD cases had concurrent cyclin D1 expression, whereas more than a third of cyclin D1-positive cases were negative for p-ERK. Ki-67 was low in RDD (median, 3%). BCL-2 was positive in lesional histiocytes in nine of 10 RDD cases assessed. Overall, these findings point to unexpected, potential roles of these molecules in the pathogenesis of RDD. Overexpression of cyclin D1 in the absence of ERK phosphorylation in a subset of RDD cases opens the possibility of oncogenic mechanisms bypassing ERK and supports the notion that cyclin D1 overexpression in RDD is multifactorial. Moreover, the observed lack of correlation between cyclin D1 with Ki-67 proliferative index suggests that prosurvival actions of cyclin D1 are, at least in part, cell cycle independent. Finally, expression of BCL-2 and the low Ki-67 index suggest that RDD might be driven by antiapoptotic rather than proproliferative oncogenic mechanisms.

Morphological and immunophenotypical analysis of the spindle cell component in adenomyomatous hyperplasia of the gallbladder.

BACKGROUND: Adenomyomatous hyperplasia (AMH) of the gallbladder, reported in 1-8.7% of cholecystectomies, consists of cystically dilated sinuses/glands with a surrounding spindle cell proliferation which is thought to be composed of smooth muscle cells. Myofibroblasts are contractile cells that secrete a variety of biochemical modulators causing a "field-effect". Myofibroblasts can be immunohistochemically distinguished from smooth muscle cells by their desmin negativity. METHODS: Eighteen cases of AMH and five cases each of chronic follicular cholecystitis, chronic cholecystitis, gallbladder carcinoma and 10 colonic diverticular disease were stained with actin and desmin. The percentage of myofibroblasts was estimated by the difference between actin and desmin staining in the same field. Statistical anlysis was performed using SPSS 22.0. RESULTS: The percentage of actin staining was significantly higher in AMH and gallbladder carcinoma compared to chronic follicular and chronic cholecystitis (p = 0.04). The percentage of desmin staining did not show any significant difference between the four groups. The estimated myofibroblastic population was significantly higher in AMH when compared to chronic follicular and chronic cholecystitis (p = 0.005). CONCLUSION: The spindle cell proliferation around cystically dilated glands in AMH is composed predominantly of myofibroblasts and of smooth muscle cells as previously described. This finding suggest a derangement in epithelial-stromal interactions as the underlying pathophysiology in AMH.

Analysis of Genetic Alterations in Cutaneous Malignant Melanomas Unveils Unique Loco-Regional Variations and Novel Predictors of Metastatic Potential.

ABSTRACT: Cutaneous malignant melanoma is an aggressive cancer that contributes significantly to cancer-related mortality. Over the years, a deeper scrutiny of melanoma biology has led to identification of diverse evolutionary patterns involving various genetic pathways. This study attempts to further understand the genetic landscape of cutaneous malignant melanoma in terms of loco-regional variations and malignant potential. Thirty-five cases of cutaneous malignant melanoma were retrieved from the archives and were classified based on location of the primary tumor and presence or absence of metastatic disease. Next-generation sequencing data consisting of base substitutions, copy number variations, indels, and rearrangements in a total of 324 genes were analyzed for recurrent genetic alterations. Statistical analysis was performed using IBM SPSS26 software. Mutations in KDM gene family were found in 62.5% of the melanomas in the head and neck as compared with 10% in melanomas of the extremity and trunk (P = 0.03). Mutations in the RAS gene family were found in 70% of melanomas in the extremities as compared to 12.5% in melanomas of the head and neck (P = 0.003). BTK gene mutations were found exclusively in melanomas of the head and neck (P = 0.032). CREBBP mutations were seen in 50% of the nonmetastatic melanomas as compared with 3.57% of metastatic melanomas (P = 0.005). This study highlights the loco-regional variations in cutaneous malignant melanoma for genetic alterations involving the KDM, RAS, and BTK gene family. In addition, the CREBBP mutational status is identified as a potential prognostic marker for predicting metastatic potential in cutaneous malignant melanomas.

Cellular senescence evaluated by P16INK4a immunohistochemistry is a prevalent phenomenon in advanced calcific aortic valve disease.

BACKGROUND: Fibrosis, calcification, and ossification are histopathologic hallmarks of calcific aortic valve disease (CAVD), a leading cause of morbidity and mortality in the aging population. Cellular senescence contributes to a functional decay in chronic diseases by intensifying tissue remodeling and impairing tissue regeneration. We evaluated the expression of P16INK4A and P53 as surrogate markers of senescence in CAVD. METHODS: Aortic valves from 27 individuals with severe CAVD requiring aortic valve replacement were selected for routine histologic processing. Immunohistochemical expression of P16INK4A and P53 was quantified using computerized image analysis on fields matching compartments with varying degrees of tissue remodeling. RESULTS: All aortic valves demonstrated P16INK4A and P53-positive cells. The percentage of P16INK4A -positive cells, but not of P53, was higher in areas of calcification and/or ossification (57.21%±26.31, n=40) and severe fibrosis (54.79%±27.19, n=25) than in areas with minimal to mild tissue remodeling (13.69% ± 11.88, n=16, P<.0001). P16INK4A expression was observed in interstitial valve cells within all compartments proportional to the degree of fibrosis and did not correlate with age, severity of aortic stenosis, or P53 expression. Multiple linear regression analysis by backward elimination revealed P16INK4A expression was lower among statin users (P<.01). CONCLUSIONS: P16INK4A- expression is ubiquitous in calcified aortic valves and correlates with severity of tissue remodeling, suggesting a role of cellular senescence in the progression of CAVD. Further research is needed to identify possible treatment modalities as disease modifying agents for CAVD.

Collision tumors of the lung: A case report of urothelial carcinoma metastasizing to renal cell carcinoma with heterotopic ossification.

Collision tumors are rare entities that consist of at least two or more histologically and ontologically distinct tumor types within the same organ. It is still not well understood how collision tumors form; yet, three main theories have been proposed to explain the pathogenesis, including the "random collision effect," "field cancerization," and "tumor-to-tumor carcinogenesis." Collision tumors have been encountered in various body organs, including the lung. They either consist of a metastasizing tumor colliding with primary cancer or distinct primary or metastatic cancers colliding together. Here, we describe a rare case of collision tumors of the lung that consists of two metastatic carcinomas, namely renal cell carcinoma and urothelial carcinoma of the bladder. We propose that the urothelial carcinoma disseminated into several pre-existing pulmonary metastases of renal cell carcinoma with heterotopic bone formation. The possible mechanisms underlying the development of this peculiar tumor are discussed.

Title- Genomic landscape of squamous cell carcinoma- Different genetic pathways culminating in a common phenotype.

INTRODUCTION: Squamous cell carcinomas (SqCCs) are the most common solid tumors in humans and are found across multiple organ systems. Although, integrated analysis of genetic alterations divulge similarities between SqCCs from various body sites, certain genes appear to be more frequently mutated in a given SqCC. These subtle differences may hold the key to determining the differentiation characteristics and predicting aggressiveness of tumors. MATERIALS AND METHOD: Fifty-four cases of SqCCs, in which the primary location of the tumor could be ascertained by clinical and radiological findings, were included in this study. Next generation sequencing data was analyzed for recurrent genetic abnormalities. RESULTS: Genetic alterations were found in 219 genes in the 54 cases studied. TP53 mutations were found to be more frequent in pulmonary SqCCs (86.5%) as compared to non-pulmonary SqCCs (58.8%) (p<0.05). NOTCH gene family mutations and CREBBP mutations were limited to non-pulmonary SqCC (p<0.005) and were mutated in 41.2% and 17.6% cases. CONCLUSION: A detailed comparative analysis of the genetic alterations identified by sequencing identified higher frequency of TP53 mutations in lung SqCCs as compared to non-pulmonary SqCCs. NOTCH and CREBPP mutations were found to be absent in lung and head and neck SqCCs and more frequent in SqCCs from other locations.

Lost in the Clinics and Found in the Morgue: A Case of Peripheral T-cell Lymphoma Masquerading as Pneumonia.

In modern medicine, there is an increasing dependence on noninvasive imaging modalities, for diagnosis and management of diseases. Though there are definite advantages to this, they are at times offset by diagnostic pitfalls especially in entities with elusive clinical presentation.Peripheral T-cell lymphoma-not otherwise specified (PTCL-NOS) is an aggressive subtype of T-cell lymphomas that does not meet criteria for a specific subtype. Peripheral T-cell lymphoma usually has varied clinical presentations depending on the site of involvement. Vast majority of PTCL patients present with systemic disease, generalized lymphadenopathy and constitutional symptoms. Pulmonary involvement is relatively rare and is seen in approximately 10% of patients.Here in we highlight a rare case of PTCL, masquerading as pneumonia due to extensive pulmonary involvement that went undiagnosed and was discovered at autopsy. This case of malignant lymphoma of T-cell origin involving the lung, which is very rare, highlights the continued importance of medical autopsies not only as a teaching tool but also as an important adjunct to investigative medicine in uncovering lapses that can subsequently be avoided to improve patient care and decrease mortality.

Retinoblastoma co-repressor 1 (RB) and cyclin-dependent kinase inhibitor (CDKN) as a multi-gene panel for differentiating pulmonary from non-pulmonary origin in metastatic neuroendocrine carcinomas.

BACKGROUND: Neuroendocrine carcinomas (NECs) arise from neuroendocrine cells present throughout the body, and often present with metastases even with small and undetectable primary tumors. Additionally, neuroendocrine differentiation can be seen in carcinomas of non-neuroendocrine origin further complicating the landscape of metastatic NECs. Organ specific immunohistochemical markers such as TTF1, CDX2 and PAX8 are often lost in high grade tumors and may be non-contributory in localizing the primary site. Though NECs share a common cellular origin, they exhibit great variability in biologic behavior, prognosis and treatment based on the primary organ of origin. DESIGN: Twenty one cases of metastatic NECs were retrieved from our archives and were classified based on location of the primary tumor derived from clinical and radiological findings. Next generation sequencing data was retrieved and analyzed for recurrent genetic abnormalities in these cases. Statistical analysis was performed using IBM SPSS25 software. RESULTS: RB1 mutations were exclusive to NECs metastasizing from lung primary and were detected in 5 of 12 (41.6 %) cases (p = 0.04). CDKN gene family (CDKN1B and 2 A) mutations were limited to metatstatic NECs of non-pulmonary origin and were detected in 4 of 9 (44.4 %) cases (p = 0.02). CONCLUSION: The location of the primary tumor in metastatic NECs appears to have significant prognostic and therapeutic implications. But due to the morphological homogeneity, higher grade of tumor, variable sensitivity of immunohistochemical markers, and small, often undetectable primary tumors, the localization of the primary tumor in cases of metastatic NECs is a challenge. In this study, RB1 and CDKN gene family mutations are identified as possible markers for differentiating pulmonary and non-pulmonary origin in metatstatic NECs.

Reactivation of Epstein-Barr Virus Presenting as Massive Splenomegaly after Initiation of Golimumab Treatment.

Epstein-Barr virus infection is most commonly asymptomatic in the acute setting, where the end result of infection is the adoption of a viral latency phenotype. The virus can reactivate later in life leading to the abnormal proliferation of the infected B, T, or NK cells. Hereby, we report a 71-year-old female with seronegative rheumatoid arthritis who presented with massive splenomegaly, pancytopenia, and positivization of antibodies against double-stranded deoxyribonucleic acid (dsDNA) after initiation of the anti-tumor necrosis factor (TNF) golimumab. The diagnosis of EBV-associated lymphoproliferative disorder (LPD) was demonstrated by elevation of the plasmatic EBV viral load. Withdrawal of the anti-TNF and treatment with the anti-CD20 antibody rituximab were able to revert the clinical abnormalities. EBV-associated LPDs are described after initiation of other anti-TNF agents, such as infliximab, but no reports of golimumab-associated EBV LPD are found in the literature. The mechanisms for this occurrence are not clear, but these are known to involve expression of a panel of viral proteins specific to the viral latency phenotypes.

Clinical, histopathologic, and immunoarchitectural features of dermatopathic lymphadenopathy: an update.

Dermatopathic lymphadenopathy is a distinctive form of paracortical lymph node hyperplasia that usually occurs in the setting of chronic dermatologic disorders. The aim of this study is to update our understanding of the clinicopathologic and immunophenotypic features of dermatopathic lymphadenopathy. The study cohort was 50 lymph node samples from 42 patients diagnosed with dermatopathic lymphadenopathy. The patients included 29 women and 13 men with a median age of 49 years (range, 12-79). Twenty-two (52%) patients had a dermatologic disorder, including mycosis fungoides (n = 6), chronic inflammatory dermatoses (n = 13), melanoma (n = 1), squamous cell carcinoma (n = 1), and Kaposi sarcoma in the context of human immunodeficiency virus infection (n = 1). Twenty (48%) patients did not have dermatologic manifestations. Lymph node biopsy specimens were axillary (n = 22), inguinal (n = 21), cervical (n = 4), and intramammary (n = 3). All lymph nodes showed paracortical areas expanded by lymphocytes; dendritic cells, including interdigitating dendritic cells and Langerhans cells; and macrophages. Melanophages were detected in 48 (98%) lymph nodes. Immunohistochemical analysis provided results that are somewhat different from those previously reported in the literature. In the paracortical areas of lymph node, S100 protein was expressed in virtually all dendritic cells, and CD1a was expressed in a significantly greater percentage of cells than langerin (80 vs. 35%, p < 0.0001). These results suggest that the paracortical regions of dermatopathic lymphadenopathy harbor at least three immunophenotypic subsets of dendritic cells: Langerhans cells (S100+, CD1a+(high), langerin+), interdigitating dendritic cells (S100+, CD1a+(low), langerin-), and a third (S100+, CD1a-, langerin-) minor population of dendritic cells. Furthermore, in more than 60% of dermatopathic lymph nodes, langerin highlighted trabecular and medullary sinuses and cords, showing a linear and reticular staining pattern, which could be a pitfall in the differential diagnosis with Langerhans cell histiocytosis involving lymph nodes.

Pancreatic Intraepithelial Neoplasia (PanIN) as a Morphologic Marker of Pancreatobiliary Type of Ampullary Carcinoma.

The classification of ampullary adenocarcinoma into intestinal and pancreatobiliary sub-types has been found to be important in predicting prognosis and determining therapeutic strategy. Due to considerable inter-observer variability in sub-typing based solely on morphology, higher frequency of poorly differentiated cancers and low incidence of the disease, the histomorphologic classification of ampullary adenocarcinoma remains one of the grey zones in surgical pathology. Pan-IN is a well recognized precursor to pancreatic adenocarcinoma. Three studies have shown concurrent Pan-IN in patients with ampullary carcinoma, but their association with the two sub-types has not yet been reported. Fourteen cases of surgical resection for ampullary adenocarcinoma were retrieved from the archives. The cases were classified into two groups based on the presence or absence of concomitant Pan-IN. All the cases were stained for CK7, CK 20, Villin and CDX 2 and were classified as intestinal or pancreatobiliary types based on the staining pattern. All the 10 cases with Pan-IN stained negative for CDX2 and were classified as pancreatobiliary type (p = 0.01). Of the cases without Pan-IN, 3 were classified as intestinal sub-type based on morphology and CDX2 positivity and 1 was classified as pancreatobiliary type. Concomitant Pan-IN was present in 91% of pancreatobiliary type of ampullary adenocarcinoma. The grade of Pan-IN did not influence the grade or stage of the adenocarcinoma (p > 0.05). The co-occurrence of Pan-IN in a high percentage of the pancreatobiliary sub-type and its complete absence in the intestinal sub-type may serve as a strong differentiator between the two sub-types.