Non-neoplastic conditions mimicking peritoneal carcinomatosis at CT imaging

Diagnosis and treatment of peritoneal carcinomatosis - a comprehensive overview

Peritoneal carcinomatosis, which is the most common malignant process of the peritoneal cavity, originates mostly from colorectal, gastric, and gynaecological malignancies. The differential diagnosis is broad and covers primary peritoneal malignancies, as well as many benign disorders such as endometriosis, and inflammatory and infectious diseases. Peritoneal implants tend to locate in the areas of the physiological stasis of the peritoneal fluid: pelvic peritoneal reflections, right and left paracolic gutters, superior part of the sigmoid mesocolon, ileocolic area, and the right subdiaphragmatic space. The 3 most common imaging findings are ascites, nodular implants, and infiltration of the peritoneal fatty tissue. Several imaging modalities may be applied in patients with peritoneal carcinomatosis. Ultrasound has low sensitivity and specificity, and therefore plays only a marginal role. Computed tomography is the method of choice, due to its availability, cost-effectiveness, and relatively high sensitivity. The sensitivity of magnetic resonance imaging depends on the size of peritoneal implants - in cases of implants larger than 10 mm is comparable to CT. Some studies suggest that PET/CT may be the most sensitive method, yet its usefulness in everyday practice is controversial. The Peritoneal Carcinomatosis Index (PCI) is a scale used to assess the tumour burden in the peritoneum and may serve as a communication tool between clinicians and radiologists. The imaging findings may influence the surgeon's decision on performing cytoreductive surgery, which may be followed by intraperitoneal chemotherapy (HIPEC or EPIC procedures). The introduction of these therapeutic methods has significantly improved the life expectancy of patients with peritoneal carcinomatosis.

Ultrasound-Guided Omental Biopsy: Diagnostic Yield and Association With CT Features Based on a Single-Institution 18-Year Series

BACKGROUND. The greater omentum can serve as a useful target for percutaneous biopsy; in clinical practice, CT is commonly used for biopsy guidance. OBJECTIVE. The purpose of this study was to evaluate the diagnostic yield of percutaneous ultrasound (US)-guided omental biopsy and to explore the association of the diagnostic yield with prebiopsy diagnostic CT findings. METHODS. This retrospective study included 163 patients (120 women and 43 men; mean age, 65 ± 12 [SD] years; mean body mass index [BMI], 28.9 ± 7.9) who underwent US-guided omental biopsy between 2002 and 2020 at a single institution at which US served as the first-line modality for omental biopsy guidance. Biopsies were performed by abdominal radiologists without dedicated interventional radiology fellowship training. Postbiopsy clinical follow-up and imaging follow-up were reviewed to establish the ultimate diagnosis for each patient. Omental biopsies were characterized as diagnostic or nondiagnostic relative to the ultimate diagnosis. Associations were explored between diagnostic yield and findings on prebiopsy CT and biopsy US. RESULTS. US-guided omental biopsy was performed using an 18-gauge core needle biopsy technique in 156 patients and fine-needle aspiration in seven patients. The mean number of biopsy passes was 2.5 ± 1.0, and mean omental thickness near the biopsy site on CT was 2.6 ± 1.2 cm. On prebiopsy diagnostic CT, omental disease appeared infiltrative in 127 (78%) patients versus mass-forming in 36 (22%) and appeared hypoechoic in 105 (64%) patients versus iso- to hyperechoic in 58 (36%). The ultimate diagnosis was malignant tumor in 154 (95%) patients (most commonly, gynecologic tumors in 82 patients [high-grade serous adenocarcinoma in 56] and gastrointestinal tumors in 45 patients) and a benign finding in nine (6%) patients. The omental biopsy was diagnostic relative to the ultimate diagnosis in 155 (95%) patients. A diagnostic versus nondiagnostic biopsy was not associated (p > .05) with age, BMI, number of biopsy passes, or omental target thickness or attenuation. A total of 94% (120/127) of US-guided omental biopsies of infiltrative cases and 97% (35/36) of biopsies of mass-forming cases were diagnostic (p = .50). A total of 96% (102/106) of US-guided omental biopsies of hypoechoic cases and 93% (53/57) of biopsies of iso- to hyperechoic cases were diagnostic (p = .36). No complications occurred. CONCLUSION. US-guided biopsy of omental disease suspected on CT is safe and effective for tissue diagnosis. Although omental disease commonly appears on US as diffuse infiltrative thickening without a discrete target, sampling based on prebiopsy CT landmarks is diagnostic in most cases. CLINICAL IMPACT. US should be considered the first-line modality for omental biopsy guidance when feasible.

Amyloidosis: Multisystem Spectrum of Disease with Pathologic Correlation

Amyloidosis is a group of conditions defined by extracellular deposition of insoluble proteins that can lead to multiorgan dysfunction and failure. The systemic form of the disease is often associated with a plasma cell dyscrasia but may also occur in the setting of chronic inflammation, long-term dialysis, malignancy, or multiple hereditary conditions. Localized forms of the disease most often involve the skin, tracheobronchial tree, and urinary tract and typically require tissue sampling for diagnosis, as they may mimic many conditions including malignancy at imaging alone. Advancements in MRI and nuclear medicine have provided greater specificity for the diagnosis of amyloidosis involving the central nervous system and heart, potentially obviating the need for biopsy of the affected organ in certain circumstances. Specifically, a combination of characteristic findings at noninvasive cardiac MRI and skeletal scintigraphy in patients without an underlying plasma cell dyscrasia is diagnostic for cardiac transthyretin amyloidosis. Histologically, the presence of amyloid is denoted by staining with Congo red and a characteristic apple green birefringence under polarized light microscopy. The imaging features of amyloid vary across each organ system but share some common patterns, such as soft-tissue infiltration and calcification, that may suggest the diagnosis in the appropriate clinical context. The availability of novel therapeutics that target amyloid protein fibrils such as transthyretin highlights the importance of early diagnosis. Online supplemental material is available for this article. ^©RSNA, 2021.

Peritoneal thickening: It's not always carcinomatosis

The peritoneal pseudotumor localization of tuberculosis is a rare clinical form, representing 1 to 3% of extrapulmonary site of tuberculosis. It represents the sixth most common extra pulmonary site of tuberculosis. It is a great mimicker with major overlapping clinical and imaging features. Differentiating peritoneal tuberculosis and peritoneal carcinomatosis in imaging remains challenging. We present a case of a 37-year old woman complaining of chronic abdominal pain and distension who has been diagnosed to have peritoneal carcinomatosis based on CT findings, histopathological study then revealed necrotizing, granulomatous inflammation consistent with tuberculosis. This case showed the interest to be aware of the common and uncommon imaging features of tuberculosis by radiologists to better assess for alternative differential diagnosis.

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.

Nanotechnology for Cancer Imaging: Advances, Challenges, and Clinical Opportunities

Nanoparticle (NP) imaging applications have the potential to improve cancer diagnostics, therapeutics, and treatment management. In biomedical research and clinical practice, NPs can serve as labels or labeled carriers for monitoring drug delivery or serve as imaging agents for enhanced imaging contrast, as well as providing improved signal sensitivity and specificity for in vivo imaging of molecular and cellular processes. These qualities offer exciting opportunities for NP-based imaging agents to address current limitations in oncologic imaging. Despite substantial advancements in NP design and development, very few NP-based imaging agents have translated into clinics within the past 5 years. This review highlights some promising NP-enabled imaging techniques and their potential to address current clinical cancer imaging limitations. Although most examples provided herein are from the preclinical space, discussed imaging solutions could offer unique in vivo tools to solve biologic questions, improve cancer treatment effectiveness, and inspire clinical translation innovation to improve patient care. Keywords: Molecular Imaging-Cancer, Molecular Imaging-Nanoparticles, Molecular Imaging-Optical Imaging, Metastases, Oncology, Surgery, Treatment Effects.

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.

Spilled stones following pyelolithotomy: An unusual mimic of peritoneal carcinomatosis

While spillage of intraperitoneal gallstones has been reported frequently in the literature, spilled renal stones after urologic intervention is rare. The dropped renal stones may mimic peritoneal carcinomatosis (PC) on imaging, causing concern and potentially leading to unnecessary diagnostic workup. Additionally, these dropped stones may cause surrounding inflammation, potentially leading to the formation of adhesions or an intra-abdominal abscess. Calcifications along the peritoneal lining are generally interpreted as peritoneal carcinomatosis until proven otherwise. However, this case highlights the importance of a detailed history and comparison with prior imaging. We describe a rare case of intraperitoneal spilled renal stones after pyelolithotomy initially mistaken for PC, in addition to a review of diagnostic pitfalls and radiologic mimics of PC.