Peritoneal lymphomatosis: CT and PET/CT findings and how to differentiate between carcinomatosis and sarcomatosis

Acute abdomen revealing abdominal tuberculosis complicated by a proximal jejunal perforation: Case report

Abdominal tuberculosis (TB) remains a significant health concern globally, particularly in regions with high endemicity such as North Africa and Morocco. Despite advances in diagnostic modalities, the nonspecific presentation of abdominal TB poses challenges for timely diagnosis and management. Here, we report a case of abdominal TB in a critically state of a young man from Morocco, presenting with acute abdominal pain and signs of sepsis. Radiological investigations revealed features suggestive of intestinal perforation complicating peritoneal TB. Urgent laparotomy confirmed the diagnosis, yet the patient succumbed to advanced sepsis postoperatively. This case underscores the complexity of abdominal TB diagnosis and management, necessitating a high index of suspicion and multidisciplinary collaboration. With evolving surgical techniques and ongoing research efforts, optimizing strategies for early detection and treatment of abdominal TB remains imperative, particularly in endemic regions.

High-grade B-cell lymphoma, not otherwise specified, presenting as primary peritoneal lymphomatosis and successfully treated with dose-adjusted EPOCH-R

Peritoneal lymphomatosis (PL) is a rare lymphoma-associated condition defined as the dissemination of lymphoma cells in the peritoneum. An 82-year-old man presented with abdominal pain, heartburn, and high fever. Radiological findings, including positron emission tomography-computed tomography (PET-CT), and gastrointestinal fiberscopy, showed diffuse thickening of the peritoneum, omentum, and mesentery; however, no lymphadenopathy, hepatosplenomegaly, or gastrointestinal lesions were observed. Under suspicion of peritonitis carcinomatosa of unknown origin, exploratory laparoscopy was performed that revealed multiple white nodules and masses on the surfaces of the peritoneum, mesentery, and intestinal serosa. The histopathological and cytogenetic findings of the peritoneum revealed high-grade B-cell lymphoma, not otherwise specified, and a gain of MYC by fluorescence in-situ hybridization. The patient was treated with two cycles of R-CHOP therapy, followed by six cycles of dose-adjusted EPOCH-R therapy, and a complete metabolic response was confirmed by PET-CT. Since there are no specific radiological findings to confirm the diagnosis of PL, a histopathological diagnosis is usually required. Most PL exhibit an aggressive lymphoma phenotype and can be cured by appropriate chemotherapy. Therefore, early diagnosis and treatment are desirable.

A case of peritoneal Burkitt's lymphoma mimic of peritoneal tuberculosis

Peritoneal lymphomatosis is a rare presentation of lymphoma that can mimic peritoneal tuberculosis. The computed tomography findings in both conditions include omental caking, thickening, and nodularity. We report the case of a 41-year-old man who presented with intermittent abdominal pain and distension. Abdominal CT initially suggested peritoneal tuberculosis due to the thickening of the peritoneum and greater omentum with multiple nodules. However, 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) images showed diffuse metabolic activity increase in the thickened peritoneum, omentum, and mesentery. An omental biopsy was performed under ultrasonography guidance, and histopathological examination revealed a high-grade Burkitt lymphoma. It is crucial to distinguish peritoneal lymphomatosis from tuberculosis, as the prognosis and management of the two conditions are vastly different.

Unravelling Peritoneal Carcinomatosis Using Cross-Sectional Imaging Modalities

Peritoneal carcinomatosis (PC) refers to malignant epithelial cells that spread to the peritoneum, principally from abdominal malignancies. Until recently, PC prognosis has been considered ill-fated, with palliative therapies serving as the only treatment option. New locoregional treatments are changing the outcome of PC, and imaging modalities have a critical role in early diagnosis and disease staging, determining treatment decision making strategies. The aim of this review is to provide a practical approach for detecting and characterizing peritoneal deposits in cross-sectional imaging modalities, taking into account their appearances, including the secondary complications, the anatomical characteristics of the peritoneal cavity, together with the differential diagnosis with other benign and malignant peritoneal conditions. Among the cross-sectional imaging modalities, computed tomography (CT) is widely available and fast; however, magnetic resonance (MR) performs better in terms of sensitivity (92% vs. 68%), due to its higher contrast resolution. The appearance of peritoneal deposits on CT and MR mainly depends on the primary tumour histology; in case of unknown primary tumour (3-5% of cases), their behaviour at imaging may provide insights into the tumour origin. The timepoint of tumour evolution, previous or ongoing treatments, and the peritoneal spaces in which they occur also play an important role in determining the appearance of peritoneal deposits. Thus, knowledge of peritoneal anatomy and fluid circulation is essential in the detection and characterisation of peritoneal deposits. Several benign and malignant conditions show similar imaging features that overlap those of PC, making differential diagnosis challenging. Knowledge of peritoneal anatomy and primary tumour histology is crucial, but one must also consider clinical history, laboratory findings, and previous imaging examinations to achieve a correct diagnosis. In conclusion, to correctly diagnose PC in cross-sectional imaging modalities, knowledge of peritoneal anatomy and peritoneal fluid flow characteristics are mandatory. Peritoneal deposit features reflect the primary tumour characteristics, and this specificity may be helpful in its identification when it is unknown. Moreover, several benign and malignant peritoneal conditions may mimic PC, which need to be considered even in oncologic patients.

Primary and secondary tumors of the peritoneum: key imaging features and differential diagnosis with surgical and pathological correlation

Peritoneal malignancies represent a diagnostic challenge for abdominal radiologists, oncologists, surgeons and pathologists in multidisciplinary teams, who must address their differential diagnosis, staging and treatment. In this article, we explain the pathophysiology of these processes and lay out the role of different imaging techniques in their evaluation. Then, we review the clinical and epidemiological aspects, the main radiological features and the therapeutic approaches for each primary and secondary peritoneal neoplasm, with surgical and pathological correlation. We further describe other rare peritoneal tumors of uncertain origin and a variety of entities that may mimic peritoneal malignancy. Finally, we summarize the key imaging findings of each peritoneal neoplasm to facilitate an accurate differential diagnosis that may impact patient management.Clinical relevance statementImaging plays an essential role in the evaluation of peritoneal malignancies, assessing their extension, detecting unfavorable sites of involvement and facilitating an accurate differential diagnosis, helping to choose the best therapeutic approach.

Diffuse Large B-cell Lymphoma Presenting as Peritoneal Lymphomatosis: A Case Report and Literature Review

Peritoneal lymphomatosis (PL) is a rare presentation of malignant lymphoma cases, many of which are diagnosed as diffuse large B-cell lymphoma (DLBCL) and characterized by aggressive clinical courses. We herein report a 63-year-old woman presenting with the rapid development of abdominal distention due to bulky peritoneal tumors. The pathological evaluation of a needle biopsy sample, combined with flow cytometry, yielded the diagnosis of DLBCL. Prompt chemotherapeutic intervention resulted in favorable disease control and sustained complete remission. It is necessary to diagnose cases of DLBCL presenting as PL early to ensure prompt treatment and prevent mortality.

Peritoneal malignancy: anatomy, pathophysiology and an update on modern day imaging

With increasing subspecialised experience in radical cytoreductive surgery and intra-abdominal chemotherapy for peritoneal malignancy, outcomes have improved significantly in selected patients. The surgery and the treatment regimens are radical and therefore correct patient selection is critical. The radiologist plays a central role in this process by estimating, as precisely as possible, the pre-treatment disease burden. Because of the nature of the disease process, accurate staging is not an easy task. Tumour deposits may be very small and in locations where they are very difficult to detect. It must be acknowledged that no form of modern day imaging has the capability of detecting the smallest peritoneal nodules, which may only be visible to direct inspection or histopathological evaluation. Nonetheless, it behoves the radiologist to be as exact and precise as possible in the reporting of this disease process. This is both to select patients who are likely to benefit from radical treatment, and just as importantly, to identify patients who are unlikely to achieve adequate cytoreductive outcomes. In this review, we outline the patterns of spread of disease and the anatomic basis for this, as well as the essential aspects of reporting abdominal studies in this patient group. We provide an evidence-based update on the relative strengths and limitations of our available multimodality imaging techniques namely CT, MRI and positron emission tomography/CT.

Peritoneal disease: key imaging findings that help in the differential diagnosis

The peritoneum is a unique serosal membrane, which can be the site of primary tumors and, more commonly, secondary pathologic processes. Peritoneal carcinomatosis is the most common malignant condition to affect the peritoneal cavity, and the radiologist plays an important role in making the diagnosis and assessing the extent of disease, especially in sites that may hinder surgery. In this review, we address the role of the radiologist in the setting of peritoneal pathology, focusing on peritoneal carcinomatosis as this is the predominant malignant process, followed by revising typical imaging findings that can guide the differential diagnosis.We review the most frequent primary and secondary peritoneal tumor and tumor-like lesions, proposing a systemic approach based on clinical history and morphological appearance, namely distinguishing predominantly cystic from solid lesions, both solitary and multiple.

Diffuse large B-cell lymphoma initially presenting with peritoneal dissemination

A 62-year-old woman with a severely distended abdomen and no palpable superficial lymph nodes visited the hospital. Computed tomography with contrast enhancement revealed multiple fused and homogeneously contrasting masses filling the abdominal cavity. She was diagnosed with diffuse large B-cell lymphoma by ultrasound-guided needle biopsy performed on admission.

Non-Hodgkin's Lymphoma Presenting as Isolated Peritoneal Lymphomatosis: A Case Report and Literature Review

Peritoneal lymphomatosis is extremely rare and associated with poor prognosis. Most practitioners only pay more attention to peritoneal carcinomatosis. However, peritoneal lymphomatosis can be neglected and misdiagnosed. We report a teenager with 10 days of abdominal distension and pain accompanied by computed tomography scan suggesting diffuse thickening of the peritoneum and omentum and abdominopelvic effusion. Tuberculous peritonitis and peritoneal carcinomatosis were initially suspected. However, it was finally confirmed as non-Hodgkin’s B-cell lymphoma by omentum biopsies. He achieved complete remission after chemotherapy and autologous stem cell transplantation. But unfortunately, he suffered a relapse and died 10 months after diagnosis. Following a review of the literature, it can be concluded that the discovery of lymphomatosis in peritoneum is a rare finding. Lymphoma should be considered in the differential diagnosis of unexplained peritoneal thickening on computed tomography, and this case emphasizes the importance of early pathological diagnosis to make sure that the right treatment can be started opportunely.

Immunoglobulin G4-related systemic disease: mesenteric and peritoneal involvement with radiopathological correlation and differential diagnoses

Since its first introduction in 2003 by Kamisawa et al., IgG4-related disease has gained wide interest in the imaging community, and several manuscripts have been published regarding its imaging features. In addition to initial observations in the pancreaticobiliary system, it is now well known that the disease may involve every organ system in the body. There is not much information in the imaging literature about the involvement of mesentery, omentum, and peritoneum in this disease. This article aims to provide more information about the imaging findings of IgG4-related disease regarding these areas by making radiopathological correlations and discussing the possible differential diagnoses.

Peritoneal Lymphomatosis: The Great Mimicker

Peritoneal lymphomatosis (PL) is defined as intraperitoneal dissemination of lymphoma. Although rare, it is associated with high-grade lymphomas and can be easily mistaken for peritoneal carcinomatosis (PC) on imaging, which is a common condition associated with gastrointestinal and gynecological malignancies. Both PL and PC share similar radiographic features, however, they differ considerably in terms of prognosis and management. We present a case of a 58-year-old male with abdominal distention and ascites, initially reported as having PC on imaging. A subsequent peritoneal biopsy revealed PL secondary to a low-grade follicular lymphoma. Since PL responds well to chemotherapy, its prompt diagnosis and differentiation from PC helps avoid unnecessary surgery.

CT imaging review of uncommon peritoneal-based neoplasms: beyond carcinomatosis

Pathologic involvement of the peritoneum can result from a wide variety of conditions, including both neoplastic and non-neoplastic entities. Neoplastic involvement of the peritoneal ligaments, mesenteries, and spaces from malignant spread of epithelial cancers, termed peritoneal carcinomatosis, is frequently encountered at CT evaluation. However, a host of other more unusual benign and malignant neoplasms can manifest with peritoneal disease, including both primary and secondary peritoneal processes, many of which can closely mimic peritoneal carcinomatosis at CT. In this review, we discuss a wide array of unusual peritoneal-based neoplasms that can resemble the more common peritoneal carcinomatosis. Beyond reviewing the salient features for each of these entities, particular emphasis is placed on any specific clinical and CT imaging clues that may allow the interpreting radiologist to appropriately narrow the differential diagnosis and, in some cases, make an imaging-specific diagnosis.

Peritoneal lymphomatosis. A case report

Introduction

Involvement of the peritoneum occurs very rarely and is exceptional as an exclusive extranodal presentation of lymphomas. In most cases lymphomas associated with this rare entity are high-grade ones. PL secondary to high-grade nodal lymphoma is more frequent than primary peritoneal lymphoma, and there are only a few cases of the latter described in the literature.

Description of the case

We present the case of a patient with constitutional syndrome and imaging findings suggestive of peritoneal carcinomatosis who was finally diagnosed with a Diffuse Large B-cell Lymphoma (DLBCL) by an ultrasound-guided core needle biopsy (CNB) of peritoneum. The patient received one polychemotherapy cycle; however tumor lysis syndrome occurred with death of the patient in the following days.

This case tries to show the existence of a PL without other radiological findings of lymphoma, a fact that is very exceptionally described in the literature.

Discussion

The differential diagnosis between PL and others peritoneum diseases such as peritoneal carcinomatosis, malignant primary peritoneal mesotheliomas, tuberculous peritonitis, sarcomatosis, diffuse peritoneal leiomyomatosis or benign splenosis, constitutes a major problem in imaging techniques.

An exhaustive analysis of the radiological characteristics as well as a clinical-analytical context allows the differential diagnosis against peritoneal carcinomatosis and the rest of the entities previously referred although the final diagnosis will always be a biopsy.

Conclusion

PL usually manifests as an aggressive histological subtype of high-grade lymphomas leading to a rapid progression and deterioration of the patient. It is crucial for the radiologist and the clinician to be aware of this rare entity providing the earliest possible diagnosis and optimal treatment to prolong the patient's life.

A TLR4-TRIF-dependent signaling pathway is required for protective natural tumor-reactive IgM production by B1 cells

Metastatic cancer involving spread to the peritoneal cavity is referred to as peritoneal carcinomatosis and has a very poor prognosis. Our previous studies demonstrated a toll-like receptor 4 (TLR4) and C-type lectin receptor (CLR; Mincle/MCL) agonist pairing of monophosphoryl lipid A (MPL) and trehalose-6,6'-dicorynomycolate (TDCM) effectively inhibits peritoneal tumor growth and ascites development through a mechanism dependent upon B1a cell-produced natural IgM, complement, and phagocytes. In the current study, we investigated the requirement for TLR4 and Fc receptor common γ chain (FcRγ), required for Mincle/MCL signaling, in the MPL/TDCM-elicited response. MPL/TDCM significantly increased macrophages and Ly6Chi monocytes in the peritoneal cavity of both TLR4-/- and FcRγ-/- mice, suggesting redundancy in the signals required for monocyte/macrophage recruitment. However, B1 cell activation, antibody secreting cell differentiation, and tumor-reactive IgM production were defective in TLR4-/-, but not FcRγ-/- mice. TRIF was required for production of IgM reactive against tumor- and mucin-related antigens, but not phosphorylcholine, whereas TLR4 was required for production of both types of reactivities. Consistent with this, B1 cells lacking TLR4 or TRIF did not proliferate or differentiate into tumor-reactive IgM-producing cells in vitro and did not reconstitute MPL/TDCM-dependent protection against peritoneal carcinomatosis in CD19-/- mice. Our results indicate a TLR4/TRIF-dependent pathway is required by B1 cells for MPL/TDCM-elicited production of protective tumor-reactive natural IgM. The dependency on TRIF signaling for tumor-reactive, but not phosphorylcholine-reactive, IgM production reveals unexpected heterogeneity in TLR4-dependent regulation of natural IgM production, thereby highlighting important differences to consider when designing vaccines or therapies targeting these specificities.

The Peritoneum: What Nuclear Radiologists Need to Know

The peritoneum is the largest and most complex serous membrane in the human body. The peritoneal membrane is composed of a layer of mesothelium supported by a thin layer of connective tissue. The peritoneum is one continuous sheet, forming two layers and a potential space between them - the peritoneal cavity- which is subdivided into multiple communicating spaces containing small amount of serous fluid that facilitates frictionless movement of mobile intraabdominal viscera. Peritoneum also contributes to fluid exchange mechanism and plays a role in immune response. The peritoneum is subject to many neoplastic and non-neoplastic processes including infections, trauma, developmental and inflammatory processes. Different Nuclear Medicine imaging techniques can be used to diagnose peritoneal diseases, most of these techniques can be customized depending on the clinical scenario and expected findings. Peritoneal scintigraphy can detect abnormal peritoneal communication or compartmentalization. Several nuclear medicine techniques can help characterize intraperitoneal fluid collections and differentiate sterile from infected fluid. PET imaging plays an important role in imaging of different neoplastic and non-neoplastic peritoneal pathologies. Nuclear radiologists need to be familiar with peritoneal anatomy and pathology to interpret peritoneal findings in dedicated peritoneal nuclear medicine imaging studies, as part of more general nuclear medicine scans, or on CT or MRI component of hybrid imaging studies. The purpose of this article is to review the normal peritoneal anatomy, various pathologic processes involving the peritoneum, and different nuclear medicine and hybrid imaging techniques that can help detect, characterize, and follow up peritoneal pathology.

A Rare, Yet Treatable Pancreatic Tumor: Epstein-Barr Virus-Positive Diffuse Large B-Cell Lymphoma

BACKGROUND Epstein-Barr virus (EBV)-positive diffuse large B-cell lymphoma (DLBCL) is a rare subtype of B-cell neoplasm that can have diverse presentations. When it involves the pancreas (i.e., pancreatic lymphoma), it can mimic metastatic pancreatic adenocarcinoma. Pancreatic lymphoma and adenocarcinoma often have similar clinical, laboratory, and radiographic features making the distinction challenging without pathological tissue examination. The differentiation of these 2 entities is important as the prognosis of pancreatic lymphoma is certainly more favorable with a chance of cure with chemoimmunotherapy. CASE REPORT We present an unusual case of EBV-positive DLBCL involving the pancreas that was initially believed to be metastatic pancreatic adenocarcinoma. The patient was treated with chemoimmunotherapy and had a remarkable response. This is the first known case of EBV-positive DLBCL involving the pancreas that was successfully treated with chemoimmunotherapy. CONCLUSIONS EBV-positive DLBCL can have diverse presentations, including a pancreatic mass with multi-organ involvement, which mimics metastatic pancreatic adenocarcinoma. The prognosis of EBV-positive DLBCL is thought to be worse than that of EBV-negative tumors. However, it remains certainly superior to that of its adenocarcinoma counterpart with conventional chemoimmunotherapy.

Fat misbehaving in the abdominal cavity: a pictorial essay

Intra-abdominal fat is abundantly present in both the peritoneum and retroperitoneum. Fat necrosis or inflammation are common findings in abdominal imaging. The most common pathologies that we encounter are epiploic appendagitis, omental infarction, mesenteric panniculitis, and encapsulated fat necrosis. Less common entities that can occur are pancreatic saponification, heterotopic mesenteric ossification, and pseudolipoma of the capsule of Glisson. These entities can mimic more urgent pathologies such as appendicitis, diverticulitis, or malignancies.

Appendix Tumor Microenvironment

The pathological features of the appendix tumors fundamentally recall those of the more frequent colorectal neoplasms, although with a higher relative incidence of carcinoids, due to the abundant presence of enteroendocrine cells in the appendix wall. Moreover, different types of lymphomas, Hodgkin and non-Hodgkin, arising from the extra-nodal mucosal-associated lymphatic tissue, can be encountered. The appendix tumor microenvironment (TME) consists of a cellular component and of a noncellular component: the former includes the immunocompetent cells, while the latter represents the support stroma. Particularly in carcinoids, the immune cell reaction can be explicated by tumor-infiltrating lymphocytes, which, in some circumstances, may arrange around and inside the tumor in a brisk fashion influencing favorably the prognosis. This active reaction has to be distinguished from any preexisting inflammatory condition of the appendix and from superimposed tumor complications, such as infection or ischemia. In practice, we consider the appendix TME a complex framework with immunological, mechanic, and metabolic functions, all supported by a marked neo-lymphoangiogenesis.

Foliate Lymphoid Aggregates as Novel Forms of Serous Lymphocyte Entry Sites of Peritoneal B Cells and High-Grade B Cell Lymphomas

The cellular homeostasis of lymphoid tissues is determined by the continuous interactions of mobile hematopoietic cells within specialized microenvironments created by sessile stromal cells. In contrast to the lymph nodes and mucosal lymphoid tissues with well-defined entry and exit routes, the movement of leukocytes in the peritoneal cavity is largely unknown. In this study, we report that, in addition to the omental milky spots and fat-associated lymphoid clusters, in mice, the serous surface of the mesenteric adipose streaks contains lymphocyte-rich organoids comprised of a highly compacted leaf-like part connected to the adipose tissue that can also efficiently bind B cells and high-grade B cell lymphoma (diffuse large B cell lymphoma) cells. Denoted as foliate lymphoid aggregates (FLAgs), these structures show incomplete T/B segregation and a partially differentiated stromal architecture. LYVE-1-positive macrophages covering FLAgs efficiently bind i.p. injected normal B cells as well as different types of diffuse large B cell lymphoma cells. Within FLAgs, the lymphocytes compartmentalize according to their chemokine receptor pattern and subsequently migrate toward the mesenteric lymph nodes via the mesenteric lymphatic capillaries. The blood supply of FLAgs includes short vascular segments displaying peripheral lymph node addressin, and the extravasation of lymphocytes to the omental and mesenteric adipose tissues is partly mediated by L-selectin. The appearance of i.p. injected cells in mesenteric lymph nodes suggests that the mesentery-associated lymphatics may also collect leukocytes from the fat-associated lymphoid clusters and FLAgs, thus combining the mucosal and serous exit of mobile leukocytes and increasing the range of drainage sites for the peritoneal expansion of lymphoid malignancies.

Peritoneal Carcinomatosis Arising from Primary Anorectal Melanoma

Anorectal melanoma is a rare and aggressive malignancy with a poor prognosis. Anorectal melanoma makes up approximately 1 to 3% of all anorectal malignancies. There are no known risk factors for anorectal melanoma. Patients frequently experience a delay in diagnosis due to multiple factors including nonspecific symptoms and misdiagnosis for other benign entities. Anorectal melanoma has a high potential for distant metastases and radiographic imaging plays a key role in evaluating for metastatic disease. Common sites for metastasis include pelvic lymph nodes, lungs, liver, skin, and brain. We present a case report of a 75 year old female with a history of transanal excision of primary anorectal melanoma who presented with increasing abdominal pain and distention. Computed tomography scan of the abdomen and pelvis showed metastatic disease to the peritoneum with findings of extensive peritoneal carcinomatosis, demonstrating the aggressive nature of anorectal melanoma.

Peritoneal lymphoma with ascites mimicking portal hypertensive ascites: A case report

RATIONALE

Lymphoma with an initial manifestation of ascites and peritoneal invasion is rare.

PATIENT CONCERNS

A 65-year-old woman presented to the emergency department with a 3-week history of abdominal distention, anorexia, and night sweating, and a 2-week history of melena. She was a silent hepatitis B virus carrier. Abdominal ultrasound showed massive ascites without cirrhosis. Abdominal computed tomography revealed ascites, infiltrative peritoneal lesions with omental cake appearance, and lymphadenopathies.

DIAGNOSIS

We performed paracentesis and the ascites cytology was obtained. The patient also underwent esophagogastroduodenoscopy, which showed ulcerative tumors in the stomach. Both ascites cytology and pathology of the gastric tumors confirmed the diagnosis of B-cell lymphoma.

INTERVENTIONS

This patient received 7 cycles of chemotherapy.

OUTCOMES

Follow-up imaging studies revealed partial remission of lymphoma, but an enlargement of residual tumors in omentum and mesentery, which resulted in intractable ascites and rapid deterioration of performance status. Despite a change of regimen of chemotherapy, this patient expired 10 months after diagnosis.

LESSONS

Lymphoma should be one of the differential diagnoses in patients with intractable ascites not attributable to other comorbidities.

Activation of B-1 Cells Promotes Tumor Cell Killing in the Peritoneal Cavity

Metastatic cancer involving spread to the peritoneal cavity is referred to as peritoneal carcinomatosis and has a very poor prognosis. Activating the antitumor immune response in the characteristically immune-suppressive peritoneal environment presents a potential strategy to treat this disease. In this study, we show that a toll-like receptor (TLR) and C-type lectin receptor (CLR) agonist pairing of monophosphoryl lipid A (MPL) and trehalose-6,6'-dicorynomycolate (TDCM) effectively inhibits tumor growth and ascites development in a mouse model of aggressive mammary cancer-induced peritoneal carcinomatosis. MPL/TDCM treatment similarly inhibited peritoneal EL4 tumor growth and ascites development. These effects were not observed in mice lacking B cells or mice lacking CD19, which are deficient in B-1a cells, an innate-like B-cell population enriched in the peritoneal cavity. Remarkably, adoptive transfer of B-1a cells, but not splenic B cells from WT mice, restored MPL/TDCM-induced protection in mice with B-cell defects. Treatment induced B-1 cells to rapidly produce high levels of natural IgM reactive against tumor-associated carbohydrate antigens. Consistent with this, we found significant deposition of IgM and C3 on peritoneal tumor cells as early as 5 days post-treatment. Mice unable to secrete IgM or complement component C4 were not protected by MPL/TDCM treatment, indicating tumor killing was mediated by activation of the classical complement pathway. Collectively, our findings reveal an unsuspected role for B-1 cell-produced natural IgM in providing protection against tumor growth in the peritoneal cavity, thereby highlighting potential opportunities to develop novel therapeutic strategies for the prevention and treatment of peritoneal metastases. SIGNIFICANCE: This work identifies a critical antitumor role for innate-like B cells localized within the peritoneal cavity and demonstrates a novel strategy to activate their tumor-killing potential.See related commentary by Tripodo, p. 5.

A Rare Presentation of Precursor B-cell Lymphoblastic Lymphoma in a Child

Precursor B-cell lymphoblastic lymphoma, a type of non-Hodgkin lymphoma, is common in children. It is mostly extranodal; skin, bone and soft tissue are more often involved. However, isolated peritoneal presentation is rare. In this article a unique pediatric case of isolated omental precursor B-cell lymphobastic lymphoma is presented.

Ultrasonographic features of colonic B-cell lymphoma with mesenteric lymphomatosis in a cat

A 10-year-old male neutered Domestic Shorthair cat was referred for chronic inappetence, weight loss, and hematochezia and an abdominal mass. Abdominal ultrasonography revealed a heterogeneously hypoechoic transmural colonic mass, which extended beyond the serosa and into the adjacent mesentery. Cytology and clonality assays of fine needle aspirates of the mass and mesenteric nodules yielded a diagnosis of B-cell lymphoma. Colonic lymphoma with mesenteric involvement can have a similar appearance to carcinomatosis, therefore a definitive diagnosis requires sampling and further testing of the mesenteric lesions.

Sonographic features of peritoneal lymphomatosis in 4 cats

Background

The metastatic spread of feline lymphoma to the peritoneum (“lymphomatosis”) has been rarely reported in the literature. The sonographic features specific to this rare disease manifestation have not been described and have important treatment and prognostic considerations prompting definitive diagnosis.

Objectives

To describe the ultrasonic features of feline peritoneal lymphomatosis.

Animals

Four cats with alimentary lymphoma and peritoneal metastasis confirmed using cytology, histology, or both.

Results

The sonographic features described include either a nonobstructive, focally diffuse, and circumferential intestinal mass, or an eccentric, focally diffuse, gastric mass. The intestinal and gastric lesions exhibited hypo‐to‐anechoic transmural wall thickening with loss of wall layering in association with discrete‐to‐coalescing plaques or sheets of thickened, hypoechoic tissue throughout the mesentery or omenta. All cases exhibited only small volumes of anechoic free peritoneal fluid. Three of the 4 cats also had multiple small hypoechoic nodular foci on the parietal and/or visceral peritoneal surfaces. Two cats had bilateral renomegaly because of lymphoma invasion (2/4) and 1 cat had local lymphadenopathy secondary to lymphoma invasion (1/4).

Conclusions and Clinical Importance

Peritoneal lymphomatosis is a rare manifestation of lymphoma metastasis and to date appears to be associated specifically with B‐cell alimentary lymphoma.

Unusual Case of Severe Lactic Acidosis in a Liver Transplant Patient

Lactic acidosis is a standard indicator for oxygen debt and some other very significant causes. We describe a case of liver transplant patient presenting with vague abdominal pain and lactic acidosis without any liver dysfunction/failure/ischemia/rejection or sepsis. The imaging studies showed vague bowel edema and normal hepatic perfusion. The patient continued to deteriorate with rising lactic acidosis when a repeat CT abdomen eventually showed signs of lymphomatosis peritonei. Biopsy revealed the unusual diagnosis of posttransplant lymphoproliferative disorder. Immediate discontinuation of immunosuppression and initiation of chemotherapy led to clinical improvement. Our intention of presenting this case is to increase awareness of posttransplant lymphoma and propose lactic acidosis as not only an indicator of liver dysfunction or rejection but also an aid for diagnosis of this unusual but fatal and potentially curable condition.

Peritoneal Super Scan on 18F - FDG PET-CT in a Patient of Burkitt's Lymphoma

Peritoneal lymphomatosis is seen less frequently, but when seen, it is mostly associated with aggressive variants of malignancies. FDG uptake has been reported in peritoneal lymphomatosis both in DLBCL and Burkitt's lymphoma. We report a case of Burkitt's lymphoma with involvement of entire peritoneum, which looks like a “peritoneal super scan” on FDG PET-CT.

A Case Series of diffuse large B-cell lymphoma and burkitt lymphoma presenting with peritoneal lymphomatosis

INTRODUCTION

Non-Hodgkin lymphoma (NHL) can occur at any site of the body, however diffuse and extensive involvement of the peritoneal cavity occurs rarely. Diffuse large B-cell lymphoma (DLBCL) is one of the dominant histological subtypes in extra nodal lymphoma involving the peritoneal cavity while Burkitt lymphoma is seen less commonly. We report two cases of DLBCL and one case of Burkitt lymphoma presenting with peritoneal lymphomatosis (PL).

PRESENTATION OF CASE

A retrospective review of two cases involving DLBCL and one case of Burkitt lymphoma with PL was conducted. Findings in all patients were consistent with peritoneal carcinomatosis at initial evaluation. Symptoms included longstanding vague abdominal pain and weight loss. CT imaging along with biopsies showed DLBCL in two cases and Burkitt lymphoma in one case. All three patients were treated with chemotherapy and responded very well.

DISCUSSION

We report three cases of non-Hodgkin lymphoma presenting with peritoneal lymphomatosis, a rare phenomena. Due to its nonspecific presentation, laparoscopic biopsies with subsequent pathology analysis should be undertaken as quickly and efficiently as possible to accurate diagnose and treat this condition.

CONCLUSION

DLBCL with PL may have variable and non-specific presentations. It may resemble peritoneal carcinomatosis or other neoplastic and inflammatory conditions. Focused clinical awareness, high level of suspicion, and complementary approach can lead towards accurate diagnosis. Diagnostic laparoscopy plays a crucial role in facilitating diagnosis and treatment.

Peritoneal lymphomatosis confused with peritoneal carcinomatosis due to the previous history of gastric cancer: a case report

Peritoneal lymphomatosis is a very rare disease of extranodal involvement of malignant lymphoma that is occasionally confounded with other peritoneal diseases. Herein, we reported the case of a 59-year-old woman who presented with massive ascites with prior history of stomach perforation during endoscopic procedure to treat early gastric cancer. Imaging studies showed massive ascites and tumor infiltration in the omentum and peritoneal wall. Initially, relapsed gastric cancer with peritoneal seeding was suspected based on the patient's history and imaging findings. However, final diagnosis was confirmed by ascites cytology as peritoneal lymphomatosis of diffuse large B-cell lymphoma unlike prior clinical information.