gastrointestinal

Question 1

Hypodense splenic nodules

Answer 1

• Lymphoma
• Leukemia
• Fungal infections
• Tuberculosis: In its disseminated form, tuberculosis can cause hepatosplenic microabscesses.

Question 2

Linitis plastica

Answer 2

• Schirrous stomach cancer
• lymphoma
• metastatic disease
  
  • lung
  • breast
• gastritis and peptic ulcer disease

Question 3

Polyposis

Answer 3

1. Peutz-Jeghers syndrome (PJS; hamartomas): This is the most likely diagnosis, given the multiple soft-tissue masses fi lling the duodenum
2. Familial adenomatous polyposis (adenomas
   
   1. stomach
   2. small bowel
   3. colon.
3. Juvenile polyposis (hamartomas): This can occur in the stomach, small bowel, and colon.
4. Cronkhite-Canada syndrome
   
   1. hyperplastic infl ammatory polyps
   2. loss of hair and nails
   3. hyperpigmentation
5. Cowden syndrome
   
   1. causes hamartoma
      
      1. GI tract
      2. tongue
      3. skin.

Question 4

Gallbladder mass

Answer 4

1. GB adenocarcinoma
2. Xanthogranulomatous cholecystitis (XGC):
3. Metastatic disease: The most common primary malignancy to aff ect the GB is melanoma

Question 5

Polypoid endoluminal mass

Answer 5

1. • Gastrointestinal stromal tumor (GIST)
2. Primary small-bowel adenocarcinoma
3. Carcinoid: Usually in the ileum, carcinoid is often small (< 2 cm), calcifi ed, and associated with a desmoplastic reaction, but it may present as a polyp extending into the lumen without desmoplasia.

Question 6

fat containing liver lesion

Answer 6

1. Hepatocellular carcinoma (HCC)
2. Liposarcoma (usually metastatic):
3. Angiomyolipomas
4. Teratomas: These may occur in the liver by metastatic spread, by direct invasion, or as a primary neoplasm. Primary hepatic teratoma is very rare. The combination of soft tissue, fat, and calcifi cation (bone) would be more specifi c for this entity.

Question 7

Dilated jejunum and pseudosacculation

Answer 7

1. Scleroderma: This is the most likely diagnosis, given the stacks of thin, straight duodenal and jejunal folds (hidebound). Note the dilated small bowel, which is most consistent with scleroderma.
2. Small-bowel obstruction: This may present with dilated loops, but without stacked small-bowel folds.
3. Pseudo-obstruction: A third option, this may have a similar appearance. It is either idiopathic or caused by systemic diseases with associated neuropathy or myopathy (e.g., dermatomyositis).

Question 8

toxic megacolon

Answer 8

1. Toxic megacolon due to ulcerative colitis (UC): This is the most likely diagnosis, given the combination of pseudopolyps, marked colonic dilatation, and thumbprinting.
   
   1. UC is mentioned fi rst because it is the most frequent cause of toxic megacolon.
2. Ischemic colitis: This also causes thumbprinting, pseudopolyps, and toxic megacolon.
3. Pseudomembranous colitis: This can cause toxic megacolon. A history of broad-spectrum antibiotic use, sepsis, mesenteric ischemia, or neoplasm would be supportive.

Question 9

Ileocaecal valve

Answer 9

1. Crohn disease: Crohn disease is a common cause of nodular thickening of the ileocecal valve and pericecal infl ammation, causing deformity related to fi brotic tethering. Dilatation of the terminal ileum is a feature less common than stricture formation with chronic Crohn disease, but prestenotic dilatation can occur because of backwash ileitis or a focal stricture at or near the ileocecal valve
2. Ulcerative colitis: This can cause ileocecal valve deformity and an eff aced terminal ileum due to backwash ileitis.
3. Infection (tuberculosis): This may mimic the features of Crohn disease in the terminal ileum and cecum, including ileocecal valve enlargement and deformity.
4. Carcinoid: This has a predilection for the terminal ileum and can involve the ileocecal valve or prolapse into the cecum, with associated fi brotic tethering due to desmoplastic reaction.

Question 10

Caecal volvulus

Answer 10

1. Axial cecal volvulus is rotation of the right colon/small bowel around the mesentery (90% of cases of positional cecal obstruction). Supine radiographs usually show a dilated midline loop, more often in the midabdomen to left upper quadrant.
2. Cecal bascule is cranial folding of the cecum (10% of cases of positional cecal obstruction). Radiographs show a gas collection separated from the ascending colon by a transverse fold.

Question 11

Mesenteric mass

Answer 11

1. Gastrointestinal stromal tumor (GIST):
   
   • GIST is the fi rst choice for a smoothly marginated mass in the mesentery with heterogeneous enhancement
2. Desmoid tumor (mesenteric fi bromatosis
   
   • This entity may be large and well-circumscribed with heterogeneous or homogeneous enhancement. It is most common in younger women (20–40 years of age). It is sometimes seen in Gardner syndrome, after trauma, or after pregnancy.
3. Soft-tissue sarcoma
   
   • Leiomyosarcoma, liposarcoma, fi brosarcoma, hemangiopericytoma, or malignant fi brous histiocytoma may present as a solitary mass without signifi cant adenopathy.

Question 12

Gastric target lesion

Answer 12

1. Ectopic pancreatic rest: This is the most likely diagnosis. It is a classic non-neoplastic cause of a single bull’s-eye lesion
2. Spindle cell or stromal tumor: These tumors can be singular, submucosal, and centrally necrotic/ulcerated, including leiomyoma and gastrointestinal stromal tumor (GIST). These neoplasms are typically larger on presentation.
3. Primary malignancy: These may be small, solitary, and ulcerated, such as adenocarcinoma, lymphoma, or carcinoid.
4. Eosinophilic granuloma: This can present as a bull’s-eye lesion.

Question 13

Peritoneal soft tissue

Answer 13

1. • Peritoneal malignant mesothelioma
   
   • This is the most likely diagnosis, as indicated by bowel wall thickening with soft-tissue infi ltration of the mesenteric and omental fat (caking) and minimal ascites
2. Primary peritoneal carcinoma (serous papillary carcinoma)
   
   • This option can cause omental caking, ascites, and enhancing, nodular thickening of the parietal peritoneum of the pelvis. However, normal-size ovaries suggest a peritoneal origin in these cases.
3. Peritoneal carcinomatosis
   
   • This is typically more multifocal but can cause diff use soft-tissue infi ltration, nodularity, and peritoneal thickening as well as omental caking, depending on the primary.

Question 14

C-shaped terminal ileum and caecum

Answer 14

1. Lymphoma: This is the top diagnosis, a classic cause of coned cecum with involvement of the TI.
2. Abscess from appendicitis or diverticulitis: This diagnostic option can produce mass eff ect and infl ammatory changes at the TI and cecum.
3. Crohn disease and tuberculosis: These can also produce a coned cecum with TI involvement, but circumferential rather than eccentric involvement would be more common.

Question 15

Crohns

Answer 15

1. Crohn disease:
   
   • cobblestoning
   • marked wall thickening
   • mesenteric fat stranding with the creeping fat sign
   • Chronic stricture formation
   • “fat halo” sign
   • dilatation and separation of the vasa recta of this segment along the mesenteric side, consistent with the “creeping fat” or “comb” sign.
   • “cobblestone” appearance of barium ( arrows ) within the terminal ileum
   • adjacent stricture (“string” sign).
2. Infection: Infections such as tuberculosis and Yersinia infection can involve the terminal ileum but are much less likely in this case.