What's This Complication of Crohn's Colitis? - Answer

So Fans of Rob's Radiology - The answer is a fistula from the colon with the subcutaneous tissue and soft tissue abscess.

• Crohn's - named after Dr. Crohn
• Transmural process (mucosa, submucosa, muscularis propria and adventitia) vs Ulcerative Colitis which is primarily mucosal
• One of the diseases included in Inflammatory Bowel Disease (IBD)
• Can involve anywhere from mouth to anus (but usually is either small bowel only, small bowel and colon [45%], or colon only)
• 2 peaks of presentation 15-35 then 50-80
• Risk factors - urban dwellers, whites, Jewish, family history, smoking, OCP, maybe diet
• Presentation - fever, abdominal pain, diarrhea, weight loss, obstruction, rarely blood in stool (usually means colonic involvement)
• Alternating attacks and remissions
• Initially a mucosal process that leads to transmural inflammatory changes with caseating granulomas
• Transmural inflammation leads to strictures, obstruction, fistulas, perforation, malabsorption, abscesses
• Increased risk of adenocarcinoma of colon and small bowel and lymphoma
• Skip lesions - noncontiguous involvement (unlike UC which starts at rectum and travels proximally)
• Early imaging - asymmetric, skip lesions, cobblestonse, aphthous ulcers (partial), linear ulcers, fissuring, mural thickening, inflammatory pseudopolyps
• Early CT - mural thickening, mural enhancement, target or double halo sign
• Subacute to Chronic CT - mural thickening (homogenous and nonenhancing = fibrosis or stricture vs. enhancing wall = reversible inflammatory disease); fibrofatty proliferation (creeping fat), LAD, hypervascularity, inflammatory stranding, phlegmon/abscess
• Comb sign - prominent dilated vasa recta
• Complications - sinus tracts, fistula, abscess, carcinoma
• Extraintestinal -
• Hepatobiliary - steatosis (20-50%), Primary sclerosing cholangitis (1-4%), hepatic abscess
• Pancreatic - pancreatitis
• Musculoskeletal - arthritis; sacroileitis-spondylitis
• GU - nephrolithiasis (2-10%)
• Eyes - uveitis
• Skin - erythema nodosum and erythema gangrenosum
• Lab - positive ASCA (Anti-S Cerevisiae Antibodies) and negative p-ANCA is suggestive of Crohn's while vice versa is suggestive of UC.
• Treatment - ASA, steroids, immunosuppressives for those difficult to control (Azathioprine, 6-Mercaptopurine and Remicade)
• Surgery - for severe strictures, cancer, abscesses or complicated fistulas; in uncomplicated fistulas - often a nuissance and not treated surgically just treat infections. Even after surgery it is common to have recurrence at the site of surgery.
• The above case is a complicated fistula and required surgery.
• Diet is designed based on location and severity of disease.

References - emedicine.com and AFIP Radiologic Pathology Course 7th Edition

The Arcuate Sign

The arcuate sign - is a fracture of the styloid of the fibula at the insertion of the arcuate ligament complex (arcuate ligament, popliteofibular ligament and fabellofibular ligament). It is important because fracture at this site is associated with ACL or PCL tear and posterolateral corner injury. If not caught early can lead to instability, early osteoarthritis and failure of the cruciate ligament repair.

references: http://www.ajronline.org/cgi/content/full/180/2/381 and http://radiology.rsnajnls.org/cgi/content/full/244/2/620

Pleomorphic Xanthoastrocytoma

We have FLAIR, T1, T2, postcon sag T1 and precon sag T1. The patient was in mid 20's with a history of seizures. The lesion is located near/on the surface of the supratentorial brain. It is cystic with a mural nodule. The nodule is slightly low to brain on T1 and slightly bright to brain on T2 with a avid enhancement.



Differential includes - Meningioma (because the lesion is difficult to exclude that it is not extraaxial), DIG (but the patient is way too old), ganglioglioma, Pleomorphic xanthoastrocytoma, pilocytic astrocytoma, metastasis and oligodendroglioma.



Taking history, age and characteristic imaging appearance the most likely a pleomorphic xanthoastrocytoma.

• This is a rare tumor (1% of all brain tumors)


• Wide age range in literature - but most in late teens and early 20's


• WHO II - but often recurs and not sensitive to chemo or rads


• Tx - surgery; If recurs - surgery


• Classic appearance - cystic mass with mural nodule that is adjacent to the leptomeninges


• However - 52% in literature - no cystic component


• Temporal > parietal > frontal > occipital; (10% in more than one lobe)


• CT - iso or hypoattenuating lesion on noncon


• CT - calcs rare; rare to have erosion of skull or lytic lesions


• T1 - iso to hypo to gray matter


• T2 - slightly bright or iso to gray


• T1 post con - avid enhancement


• 71% of one series - had involvement of leptomeninges hence can be confused with a meningioma


• The peripheral component is single most common feature

Reference - There is an excellent reference to superficial gliomas from the AFIP http://radiographics.rsnajnls.org/cgi/content/full/21/6/1533?eaf - highly recommend reading it.

Images are from Rob's Radiology - please don't take without permission.

Hepatocellular Carcinoma

• The 1st image is CT of liver during arterial phase. The 2nd image is during the portal venous phase and the third is during the delayed phase. This lesion is in a patient with Hepatitis B. With this enhancement pattern, the most likely diagnosis is hepatocellular carcinoma.
  
  
• Hepatocellular Carcinoma - malignant tumor of hepatocellular origin (duh)


• Most common primary malignancy of the liver


• Most commonly found in diseased livers - cirrhosis of any cause (such as alcohol), viral hepatitis, and metabolic liver disease (America - alcohol, steroid use, hemochromatosis)


• Commonly invade vascular system - especially the portal vein


• No fibrous stroma - hemorrhage and necrosis - can rupture and cause hemoperitoneum


• 3 common growth patterns - solitary, multiple nodules, diffuse infiltrative


• Presentation - fever of unknown origin, abdominal pain, malaise, hepatomegaly


• AFP can be elevated (and often is - 70-80% or so); like to see >400; >1000 can be presumptive in correct clinical setting


• Can produce paraneoplastic syndromes - erythrocytosis, hypoglycemia, hypercalcemia, hirsutism


• CT - look for signs of cirrhosis, hemochromatosis etc; arterial - hyper enhancing; PV - iso to hypodense; delayed - often iso maybe hypo - sometimes a capsule is shown


• MRI - considered the favored study - T1 - iso, hyper, hypo to liver; T2 - usually hyper; superparagmagnetic iron - may help because no or few kupffer cells;


• US - variable appearance and small ones can look like hemangioma (bright/echogenic) - larger are usually heterogenous in echogenicity
• Rare associations - thorotrast, primary sclerosing cholangitis, primary biliary cirrhosis, OCP's, 1-antitrypsin deficiency, porphyria cutanea tarda

Treatment - Percutaneous alcohol, RF ablation, TACE but definitive is transplant

Differentials - dysplastic nodules and regenerative nodules. Also consider Hemangioma and focal confluent fibrosis.

Regenerative - rarely 2cm or greater. Can be siderotic or nonsiderotic. Siderotic nodules if large enough are hyperdense nodules in the liver on noncontrast and enhance like normal liver. Siderotic may be dark on T1 and T2 (esp T2). Nonsiderotic might be bright on T1.

Dysplastic nodules - precursor to HCC. Can enhance similar to HCC but don't usually. Often bright on T1 and dark on T2.

references - emedicine.com and Radiographics. 2001;21:S117-S132. Images from Rob's Radiology collection. Please do not copy without permission.

Rob's Radiology

This is a new foray into information on radiology from my perspective. Hopefully, I will be able to update cases and interesting information. The image to the left is a fascinating case of a patient with rupture of abdominal aortic aneurysm where you can actually see the blood squirt through the defect into the retroperitoneum.