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Metastatic GIST: Correlating Disparate Radiologic Findings on CT Joe McQuaid, HMS III Gillian Lieberman, MD November, 2007 Our Patient: CH Clinical Presentation History of Present Illness • • • • 68 year-old male One week history – malaise, chills, low-grade temps Four days PTA – high grade temperatures to 103.0 °F Morning of admission – three to four BM’s that were loose and explosive but not tarry, sticky, or bloody • ROS upon admission – denies chest pain, cough, shortness of breath, sputum, dysuria, hematuria, hematochezia. • No recent travel history Past Medical History • Hypertension • Hypercholesterolemia • “Benign esophageal growth” with previous history of bleeds • Prostate cancer with surgical resection • No previous imaging studies on file Physical Findings • Vital signs upon admission: – Tc=100.6 HR=72 BP=98/68 O2=97% on RA • Physical examination notable for: – – – – General: NAD. Mucus membranes clear. Pulmonary: CTA bilaterally. No wheezes, ronchi, rales. Cardiac: Normal S1 and S2. No extra heart sounds. Abdomen: Positive BS. Soft. NTND. No abnormal masses or organomegaly noted. – Lymphatics: No cervical, supraclavicular, axillary, inguinal lymphadenopathy. • Laboratory Studies: – WBC=17.1 RBC=3.64 Hgb=10.1 Hct=31.2 – Plt Ct=418 Our Patient: Chest CT “Please evaluate for infectious etiologies” Our Patient: Chest CT with Contrast 11 mm solid nodular density Irregular, “spiculated” margins BIDMC, PACS Left upper lobe apex Our Patient: Chest CT with Contrast 12x6 mm solid, nodular density with irregular, spiculated margins Adjacent to the pleura BIDMC, PACS Chest CT: Differential Diagnoses Type of Cause Neoplasm Disease Entity Metastases BAC Lymphoma Infectious X TB X Fungal (Histoplasmosis, Aspergillus) Bacterial (Staph, Klebsiella, Strep) Noninfectious Sarcoid X Rheumatoid X Silicosis Wegener’s Histocytosis Necrotizing granulomatous vasculitis Other X Drug Toxicity X = Eliminated Our Patient: Abdominal CT “Please evaluate for infectious etiologies” Our Patient: Abdominal CT with Contrast 8.0 x 9.6 x 8.0 cm (AP, transverse, craniocaudal) heterogeneous lesion, hypoenhancing compared to the liver parenchyma multiple loculations… …and septations BIDMC, PACS Our Patient: Abdominal CT with Contrast BIDMC, PACS Multiple hypoattenuating satellite lesions Abdominal CT: Differential Diagnoses Type of Cause Disease Entity Congenital Cystic Lesions Simple cysts ADPLD Bile duct harmartomas Caroli’s disease Infective Cystic Lesions Pyogenic liver abscess Amebic liver abcess Hydatid cysts Neoplastic Cystic Lesions Cystic liver metastases Cystic HCC Billiary cystadenoma Undifferentiated embryonal sarcoma BIDMC, PACS Companion Patients Some common radiologic findings of congenital cystic lesions… Companion Patient #1: Simple Hepatic Cysts on CT • Simple Hepatic Cysts – Develop from harmartomatous tissue – Hypoattenuating lesion on nonenhanced CT scans – No enhancement of wall or contents with contrast – Round or ovoid, well defined, with a thin wall Mortele KJ et al. Radiographics 2001; 21(4) Companion Patient #2: ADPLD on CT • Autosomal Dominant Polycystic Liver Disease – Often asymptomatic – Coexists with renal cysts – Multiple homogenous, hypoattenuating lesions – Regular outline – No wall enhancement with contrast Mortele KJ et al. Radiographics 2001; 21(4) Companion Patient #3: Bile Duct Harmartomas on CT • Bile Duct Harmartomas – Scattered throughout biliary tree – 0.5-1.5 cm in diameter – More irregular outline – Do not exhibit a characteristic pattern of enhancement with contrast on CT Mortele KJ et al. Radiographics 2001; 21(4) Companion Patient #4: Caroli Disease on CT Mortele KJ et al. Radiographics 2001; 21(4) • Caroli Disease – Right upper quadrant pain, fever, jaundince – Hypoattenuated dilater cystic structures – Various sizes – Communicate with bile duct system – “Central dot sign” – enhancement within dilated bile duct on CT Abdominal CT: Differential Diagnoses Type of Cause Congenital Cystic Lesions Disease Entity X X X X Simple cysts ADPLD Bile duct harmartomas Caroli’s disease Infective Cystic Lesions Pyogenic liver abscess Amebic liver abcess Hydatid cysts Neoplastic Cystic Lesions Cystic liver metastases Cystic HCC Billiary cystadenoma Undifferentiated embryonal sarcoma BIDMC, PACS X = Eliminated Companion Patients Some common radiologic findings of infective cystic lesions… Companion Patient #5: Pyogenic Abscess on CT • Pyogenic Abscess – Often infection by e coli or clostridium – Thick-walled – Low attenuation on CT – Rim enhancement with contrast – Air pockets are diagnostic of a gas-forming organism Mortele KJ et al. Radiographics 2001; 21(4) Companion Patient #6: Amebic Liver Abscess on CT • Amebic Liver Abscess – Caused by entamoeba histolytica – In addition to above features show perilesion edema – Peripheral rim enhancement or “double target sign” Mortele KJ et al. Radiographics 2001; 21(4) Companion Patient #7: Intrahepatic Hydatid Cyst on CT • Mortele KJ et al. Radiographics 2001; 21(4) Intrahepatic Hydatid Cysts – Endemic to Mediterranean and sheep-raising contries – Contact with dog feces or contaminated food – On CT appears as hypoattenuating lesion with a distinguishable wall – Coarse calcifications of wall in 50% of cases – Daughter cysts nearby in 75% of patients Abdominal CT: Differential Diagnoses Type of Cause Congenital Cystic Lesions Infective Cystic Lesions Neoplastic Cystic Lesions Disease Entity X X X X Simple cysts ADPLD Bile duct harmartomas Caroli’s disease X Pyogenic liver abscess Amebic liver abcess Hydatid cysts Cystic liver metastases Cystic HCC Billiary cystadenoma Undifferentiated embryonal sarcoma BIDMC, PACS X = Eliminated Companion Patients Some common radiologic findings of neoplastic cystic lesions… Companion Patient #8: Cytic Liver Mets on CT • Cystic Liver Mets – Most are solid but may have partial cyst-like appearance – Mechanisms of seeding: hematogenous or peritoneal – Often with enhancement of peripheral viable irregular tissue Mortele KJ et al. Radiographics 2001; 21(4) Companion Patient #9: Cystic HCC on CT • Cystic HCC – 70% of patients will also show signs or complications of liver cirrhosis – Often with a capsule or hypervascular solid parts – May show vascular or biliary invasion Mortele KJ et al. Radiographics 2001; 21(4) Companion Patient #10: Biliary Cystadenoma on CT • Biliary Cystadenoma – Large range in size (1.5cm to 35 cm) – Multilocular slow growing lesions – 55% in the right liver lobe – On CT appears a solitary, well-defined cystic mass with a capsule and internal septa Mortele KJ et al. Radiographics 2001; 21(4) Companion Patient #11: Undifferentiated Embryonal Sarcoma on CT • Undifferentiaed Embryonal Sarcoma – Predominates in children or young adults – Pseudocapsule – Heterogeneous enhancement of the peripheral borders of the mass – Usually very large (>10 cm) Mortele KJ et al. Radiographics 2001; 21(4) Abdominal CT: Differential Diagnoses Type of Cause Congenital Cystic Lesions Infective Cystic Lesions Neoplastic Cystic Lesions Disease Entity X X X X Simple cysts ADPLD Bile duct harmartomas Caroli’s disease X Pyogenic liver abscess Amebic liver abcess Hydatid cysts X Cystic liver metastases Cystic HCC Billiary cystadenoma Undifferentiated embryonal sarcoma BIDMC, PACS X = Eliminated Our Patient: Pelvic CT “Please evaluate for infectious etiologies” Our Patient: Coronal Pelvic CT with Contrast BIDMC, PACS Our Patient: Coronal Pelvic CT with Contrast BIDMC, PACS • Within the LLQ and centered in the mesenteric fat • 4.4 x 5.4 x 5.5 cm (AP, transverse, and craniocaudal) • Lesion with thick, irregular, enhancing rim with a low density center. Well-defined borders. • Supply by several feeding vessels Our Patient: Sagittal Pelvic CT with Contrast Courtesy of Dr. Mortiz Kircher • No pathologically enlarged lymph nodes in pelvis • No free fluid • Mass is inseparable from the jejunum? Our Patient: Sagittal Pelvic CT with Contrast CT images: courtesy of Dr. Moritz Kircher Small bowel cartoon: http://concise.britannica.com/ebc/art-53188/The-walls-of-the-hollow-organs-of-the-digestive-tract Pelvic CT: Differential Diagnoses Disease Entity Adenocarcinoma of the small bowel Lymphoma Mesenteric fibromatosis (desmoid tumor) Inflammatory pseudotumor Sclerosing mesenteritis Carcinoid GIST Courtesy of Dr. Mortiz Kircher Companion Patients Let’s consider some common radiologic findings of these disease entities… Companion Patient #12: Adenocarcinoma of the Small Bowel on CT Buckley JA et al. Radiographics 1998; 18(2) • Adenocarcinoma of the small bowel – 50% are in the duodenum – On CT manifests as: • annular narrowing with abrupt edges • a discrete tumor mass (papillary or polypoid often) • an ulceration Companion Patient #13: Lymphoma on CT • Buckley JA et al. Radiographics 1998; 18(2) Lymphoma – Primary tumor mass centered on small bowel with appropriate lymph node involvement – Absence of hepatic and splenic lesions – Presents on CT: • Discrete polyp within the bowel • Nodular filling defect within the bowel • Exocentric mass extending to adjacent tissue Companion Patient #14: Mesenteric Fibromatosis on CT • Levy et al. Radiographics 2006; 26(1) Mesenteric Fibromatosis – Present with abdominal mass or abdominal pain – Looks very similar to GIST histologically and radiologically – May present as discrete mass or infiltrate small bowel – CT findings vary from homogenous soft-tissue density to masses with hypoattenuation (based on histologic composition) – Typically no contrast enhancement Companion Patient #15: Inflammatory Pseudotumor on CT • Levy et al. Radiographics 2006; 26(1) Inflammatory Pseudotumor – Often occuring in young adults – Presenting symptoms of malaise, weight loss, or fever – Nonencapsulated, nodular mass – CT findings are nonspecific: • Heterogeneous attenuation • Often with well-defined margins • Variable enhancement pattern • Rarely can involve small bowel Companion Patient #16: Sclerosing Mesenteritis on CT • Levy et al. Radiographics 2006; 26(1) Sclerosing Mesenteritis – Tumor-like masses in the mesentery composed of fibrosis and chronic inflammation – Retracts and shortens the mesentery – On CT: • Well-defined or ill-defined (variable) • Mixed fat and soft-tissue density • Many with radiating strands of fibrosis Companion Patient #17: Carcinoid Levy et al. Radiographics 2006; 26(1) Pelvic CT: Differential Diagnoses Disease Entity Adenocarcinoma of the small bowel Lymphoma Mesenteric fibromatosis (desmoid tumor) Inflammatory pseudotumor Sclerosing mesenteritis Carcinoid GIST Courtesy of Dr. Mortiz Kircher Putting it all together… An Ockham’s Razor Differential Can we find a way to relate these disparate radiologic findings? Our Ockham’s Razor Differentials Disease Entity Lymphoma Desmoid Carcinoid GIST Courtesy of Dr. Mortiz Kircher Our patient underwent a right hepatic lobectomy and a partial small bowel resection Our Patient: Surgical Pathology • Right liver lobe – Metastatic gastrointestinal stromal tumor – Multiple organizing abscesses • Small bowel – Malignant gastronintestinal stromal tumor • Invasion through muscle to mucosa • Rare mitotic figures • Necrosis with blood clot Above: Multiple mitotic centers Below: C-KIT positive staining – C-KIT positive Levy et al. Radiographics 2003; 23(2) What is Gastrointestinal Stromal Tumor (GIST)? GIST: An Overview • Most common GI mesenchymal neoplasm • Frequency between 10-20 cases per million • Most inidividuals over 50 years old at presentation • Slight male predilection • Neuro-fibromatosis type I with increased prevalance • 20% are malignant GIST: An Overview • Occurs through GI tract, mesentery, omentum, and retroperitoneum • Defined by the expression of KIT (CD117) – a tyrosine kinase growth factor receptor • Usually arises in muscularis propria of stomach or intestinal wall – Often presents with an exophytic growth pattern Anatomic Location Stomach (70%) Small Intestine (20-30%) Anorectum (7%) Colon and Esophagus (Small %) GIST: Menu of Radiologic Tests • • • CT – excellent for visualizing the anatomy as seen in this case study MR – Can be used to visualize necrosis and hemorrhage (but these factors also affect the signal-intensity pattern) – In general, a useful adjunct to CT as multiplanar capability can help to determine the organ of origin in large tumors and its relation to blood vessels US – Excellent for biopsy – Often used intraoperatively • Abdominal Radiography – Commonly used in patients presenting with signs of small intestinal obstruction from GIST – Reveals small intestinal dilation or soft-tissue masses GIST: Radiologic Features • Generally characterized by wellcircumscribed enhancing masses with central areas of low attenuation (hemorrhage, necrosis, or cyst formation) • Small intestine – Barium studies demonstrate intraluminal and submucosal masses with sharp margins – CT reveal intramural or intraluminal polyps. – 22% with extraserosal locations such that small bowel not readily evident as origin on CT. – Often enhancing masses with centers of low attenuation BIDMC, PACS GIST: Radiologic Features • Stomach BIDMC, PACS – 75% occur in body of stomach – On barium swallow have a smooth mucosal surface with features of a submucosal mass – On CT usually show an intramural component. Meanwhile 86% show extragastric extension with peripheral enhancement. Summary In this presentation we… • Generated a long list of differential diagnosis based upon the various CT findings of metastatic GIST • Used our knowledge of the anatomy of the gut wall to recognize a mesenteric mass as extending from the small intestine • Further paired down our differential diagnoses by considering and relating our radiologic findings together as a whole • Reviewed the features of GIST, including the menu of radiologic tests used in its diagnosis and the its typical imaging patterns References Buckley JA and EK Fishman. CT Evaluation of Small Bowel Neoplasms: Spectrum of Disease. 1998; 18:379-392. Burkill GJC et al. Malignant Gastrointestinal Stromal Tumor: Distribution, Imaging Features, and Pattern of Metastatic Spread. Radiology. 2003; 226(2):527-532. Levy AD et al. From the Archives of the AFIP - Gastrointestinal Stromal Tumors: Radiologic Features with Pathologic Correlation. Radiographics. 2003; 23(2):283-304. Levy AD et al. From the Archives of the AFIP – Benign Fibrous Tumors and Tumorlike Lesions of the Mesentery: Radiologic-Pathologic Correlation. Radiographics. 2006; 26:245-264 Mortele KJ et al. Cystic Focal Liver Lesions in the Adult: Differential CT and MR imaging findings. Radiographics. 2001; 21(4):895-910. O’Sullivan PJ et al. The Imaging Features of Gastrointestingal Stromal Tumours. European Journal of Radiology. 2006; 60:431-438. Sandrasegaran K et al. Gastrointestinal Stromal Tumors: CT and MRI Findings. European Radiology. 2005; 15:1407-1414. Acknowledgements My sincerest thanks goes to Dr. Moritz Kircher, who provided this case and helped to guide me through it. Many thanks also to: Gillian Lieberman, MD Jonathan Kruskal, MD Andrew Bennett, MD Maria Levantakis