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Pancreas & Spleen – FRCR 2A Radiology Question Bank

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Question 1: Acute Pancreatitis (Diagnosis)

Stem: A 50-year-old man with a history of heavy alcohol use presents with acute onset of severe, constant epigastric pain radiating to the back, nausea, and vomiting. His serum amylase and lipase levels are both elevated to more than three times the upper limit of normal.

Question: According to the revised Atlanta classification, what is the next step required to confirm the diagnosis of acute pancreatitis?

(A) Contrast-enhanced CT scan of the abdomen. (B) MRI scan of the abdomen. (C) Endoscopic Retrograde Cholangiopancreatography (ERCP). (D) No further imaging is required for diagnosis. (E) Abdominal ultrasound.

Correct Answer: (D) No further imaging is required for diagnosis.

Explanation:

  • Why (D) is correct: The diagnosis of acute pancreatitis requires two out of the following three criteria: 1) Characteristic abdominal pain, 2) Serum amylase and/or lipase > 3 times the upper limit of normal, and 3) Characteristic findings on cross-sectional imaging (CT/MRI/US). Since this patient meets the first two criteria, the diagnosis is confirmed, and imaging is not needed for diagnosis in the acute setting.
  • Why (A) is wrong: A contrast-enhanced CT is crucial for assessing severity and complications (like necrosis) but is typically performed 48-72 hours after onset, not for the initial diagnosis unless there is diagnostic uncertainty or suspicion of complications.
  • Why (B) is wrong: MRI is excellent for assessing biliary causes or complications but is not the first-line diagnostic tool.
  • Why (C) is wrong: ERCP is an invasive procedure used to treat gallstone pancreatitis, not diagnose pancreatitis itself.
  • Why (E) is wrong: Ultrasound is useful for looking for gallstones (a common cause) but is often limited by bowel gas and is not required if the clinical and biochemical criteria are met.

Key Points: Acute Pancreatitis Diagnosis

  • Revised Atlanta Criteria (Need 2 of 3):
    1. Characteristic epigastric pain (radiating to back).
    2. Amylase/Lipase > 3x upper limit of normal.
    3. Characteristic findings on imaging (CT/MRI/US).
  • Imaging Role: Not usually needed for initial diagnosis if clinical/lab criteria are met. CT is primarily for severity assessment (necrosis) and identifying complications, usually done after 48-72 hours.

Question 2: Pancreatic Pseudocyst

Stem: A 58-year-old man presents with early satiety and epigastric fullness 6 weeks after an episode of severe acute pancreatitis. A CT scan shows a large, well-defined, encapsulated, homogeneous fluid collection adjacent to the pancreas, containing no solid components or internal septations.

Question: What is the most likely diagnosis for this collection?

(A) Acute Peripancreatic Fluid Collection (APFC) (B) Pancreatic Pseudocyst (C) Acute Necrotic Collection (ANC) (D) Walled-Off Necrosis (WON) (E) Serous Cystadenoma

Correct Answer: (B) Pancreatic Pseudocyst.

Explanation:

  • Why (B) is correct: A pancreatic pseudocyst is the classic complication of interstitial oedematous pancreatitis (not necrotising). It is a mature (> 4 weeks old), encapsulated collection of simple fluid (pancreatic juice) that lacks a true epithelial lining (hence “pseudo”). It typically appears as a well-defined, thin-walled, homogeneous fluid collection on CT.
  • Why (A) is wrong: An APFC is seen early (< 4 weeks) and lacks a well-defined wall.
  • Why (C) is wrong: An ANC is seen early (< 4 weeks) in necrotising pancreatitis and contains heterogeneous material (fluid and necrotic debris).
  • Why (D) is wrong: A WON is the late (> 4 weeks), encapsulated form of an ANC, containing heterogeneous necrotic debris.
  • Why (E) is wrong: A serous cystadenoma is a primary cystic neoplasm of the pancreas, not a post-pancreatitis collection.

Key Points: Pancreatitis Fluid Collections (Revised Atlanta)

  • Interstitial Oedematous Pancreatitis:
    • < 4 weeks: Acute Peripancreatic Fluid Collection (APFC) – no wall.
    • > 4 weeks: Pseudocyst – well-defined wall, simple fluid.
  • Necrotising Pancreatitis:
    • < 4 weeks: Acute Necrotic Collection (ANC) – no wall, heterogeneous debris.
    • > 4 weeks: Walled-Off Necrosis (WON) – well-defined wall, heterogeneous debris.

Question 3: Pancreatic Adenocarcinoma

Stem: A 70-year-old man presents with painless jaundice, weight loss, and a palpable gallbladder (Courvoisier’s sign). A contrast-enhanced CT scan reveals a hypodense, ill-defined mass in the head of the pancreas. This mass is causing marked dilatation of both the common bile duct and the pancreatic duct proximal to it.

Question: The finding of dilatation of both ducts is known as the:

(A) “Double Duct Sign” (B) “Chain of Lakes” Sign (C) “Mercedes Benz” Sign (D) “Central Dot” Sign (E) “Duct Ectasia” Sign

Correct Answer: (A) “Double Duct Sign”.

Explanation:

  • Why (A) is correct: The “double duct sign” refers to the simultaneous dilatation of the common bile duct (CBD) and the main pancreatic duct (MPD). This is highly suspicious for a mass obstructing both ducts at the ampulla or in the pancreatic head, most commonly a pancreatic adenocarcinoma.
  • Why (B) is wrong: The “chain of lakes” sign describes the dilated side branches in chronic pancreatitis.
  • Why (C) is wrong: The “Mercedes Benz” sign refers to gas within a gallstone.
  • Why (D) is wrong: The “central dot” sign is seen in Caroli’s disease (dilated intrahepatic ducts surrounding a portal radicle).
  • Why (E) is wrong: Duct ectasia just means duct dilatation; “double duct” is the specific sign.

Key Points: Pancreatic Adenocarcinoma (Head)

  • Most common pancreatic malignancy (~90%).
  • Location: ~70% arise in the head.
  • Clinical: Classically painless jaundice (due to CBD obstruction), weight loss, Courvoisier’s sign (palpable, non-tender gallbladder).
  • CT/MRI Findings:
    • Hypovascular (hypodense), infiltrative mass.
    • “Double Duct Sign” (CBD + MPD dilatation).
    • Look for vascular encasement (SMA, SMV, portal vein) and metastases (liver) for staging.

Question 4: Chronic Pancreatitis

Stem: A 55-year-old man with a long history of alcohol abuse presents with chronic epigastric pain and steatorrhoea. A non-contrast CT scan of the abdomen shows diffuse calcifications scattered throughout the pancreatic parenchyma and within a dilated, irregular main pancreatic duct. The pancreas itself appears atrophic.

Question: This combination of findings is most characteristic of:

(A) Chronic Pancreatitis (B) Acute Pancreatitis (C) Pancreatic Adenocarcinoma (D) Autoimmune Pancreatitis (E) Serous Cystadenoma

Correct Answer: (A) Chronic Pancreatitis.

Explanation:

  • Why (A) is correct: This is the classic triad of advanced chronic pancreatitis: 1) Pancreatic calcifications (intraductal or parenchymal), 2) Pancreatic duct dilatation (often irregular, beaded, “chain of lakes”), and 3) Pancreatic atrophy. Alcohol abuse is the most common cause.
  • Why (B) is wrong: Acute pancreatitis presents with oedema and fluid collections, not calcifications and atrophy.
  • Why (C) is wrong: Adenocarcinoma is a focal mass; calcifications within a mass are rare (unlike in chronic pancreatitis).
  • Why (D) is wrong: Autoimmune pancreatitis causes diffuse “sausage-like” enlargement of the pancreas with a featureless duct, not calcifications.
  • Why (E) is wrong: This is a cystic neoplasm, not a diffuse calcific process.

Key Points: Chronic Pancreatitis

  • Definition: Irreversible inflammatory damage leading to fibrosis, atrophy, and loss of function.
  • Most Common Cause: Alcohol abuse.
  • CT Findings (Classic Triad):
    1. Pancreatic Calcifications (highly specific).
    2. Pancreatic Duct Dilatation (irregular, beaded, “chain of lakes”).
    3. Pancreatic Atrophy.
  • Complications: Pseudocysts, pseudoaneurysms, biliary stricture, pancreatic cancer.

Question 5: Pancreatic Neuroendocrine Tumour (PNET) – Insulinoma

Stem: A 40-year-old woman presents with recurrent episodes of confusion, sweating, and palpitations (Whipple’s triad), which are relieved by eating sugar. A multiphase CT scan of the pancreas reveals a 1.5 cm, well-defined, avidly enhancing nodule in the pancreatic tail, which is most conspicuous on the late arterial phase.

Question: Given the clinical presentation, what is the most likely diagnosis?

(A) Insulinoma (B) Gastrinoma (C) Glucagonoma (D) VIPoma (E) Pancreatic Adenocarcinoma

Correct Answer: (A) Insulinoma.

Explanation:

  • Why (A) is correct: Whipple’s triad (symptoms of hypoglycaemia, low blood glucose during symptoms, relief with glucose) is classic for an insulinoma, the most common functioning PNET. Insulinomas are typically small (<2 cm), solitary, benign, and hypervascular, appearing as brightly enhancing nodules on the late arterial phase CT/MRI.
  • Why (B) is wrong: Gastrinomas cause Zollinger-Ellison syndrome (severe peptic ulcers).
  • Why (C) is wrong: Glucagonomas cause the “4 D’s” (Diabetes, Dermatitis [necrolytic migratory erythema], DVT, Depression).
  • Why (D) is wrong: VIPomas cause WDHA syndrome (Watery Diarrhoea, Hypokalaemia, Achlorhydria).
  • Why (E) is wrong: Adenocarcinoma is hypovascular and presents with jaundice or pain, not hypoglycaemia.

Key Points: Pancreatic Neuroendocrine Tumours (PNETs)

  • Imaging: Classically hypervascular (bright on arterial phase), well-defined.
  • Insulinoma (Most Common Functioning): Small (<2cm), benign, causes hypoglycaemia.
  • Gastrinoma: Causes Zollinger-Ellison. Often in the “gastrinoma triangle.” Can be malignant.
  • Non-functioning PNET (Most Common Overall): Often large at diagnosis, can be malignant.

Question 6: IPMN (Intraductal Papillary Mucinous Neoplasm)

Stem: An asymptomatic 70-year-old man has an incidental finding on an abdominal MRI. There is a cluster of small cysts in the pancreatic uncinate process, which communicate with a mildly dilated pancreatic side branch but do not communicate with the main pancreatic duct.

Question: Based on the International Consensus Guidelines, what type of IPMN is this most likely to be?

(A) Main Duct IPMN (MD-IPMN) (B) Branch Duct IPMN (BD-IPMN) (C) Mixed Type IPMN (D) Serous Cystadenoma (E) Mucinous Cystic Neoplasm (MCN)

Correct Answer: (B) Branch Duct IPMN (BD-IPMN).

Explanation:

  • Why (B) is correct: BD-IPMN arises from the side branches of the pancreatic duct. They typically appear as clusters of small cysts (“bunch of grapes”) that communicate with a side branch, but the main duct itself is normal (< 5 mm) or only mildly dilated. They have a lower risk of malignancy than MD-IPMN.
  • Why (A) is wrong: MD-IPMN involves diffuse or segmental dilatation of the main pancreatic duct (> 5 mm), often with visible mucin globules. It has a high risk of malignancy.
  • Why (C) is wrong: Mixed type involves both the main duct and side branches.
  • Why (D) is wrong: A serous cystadenoma is a collection of tiny microcysts (“honeycomb”) and does not communicate with the duct system.
  • Why (E) is wrong: An MCN is typically a large, unilocular or macrocystic lesion, almost always in the body/tail of the pancreas in middle-aged women, and does not communicate with the duct system.

Key Points: IPMN

  • Definition: Mucin-producing neoplasms arising from the pancreatic ducts. Pre-malignant.
  • Main Duct (MD-IPMN): Dilated main duct (>5mm). High risk of malignancy. Usually requires resection.
  • Branch Duct (BD-IPMN): Cystic lesion communicating with a side branch. Main duct normal. Lower risk. Can be monitored if no “high-risk stigmata” or “worrisome features.”
  • Mixed Type: Features of both. High risk.

Question 7: Serous Cystadenoma

Stem: A 65-year-old woman has an incidental finding on CT. There is a 4 cm, well-defined, lobulated mass in the head of the pancreas. The mass is composed of innumerable, tiny (<1 cm) microcysts, giving it a “honeycomb” appearance. A central, stellate scar with “sunburst” calcification is present.

Question: This appearance is pathognomonic for:

(A) Serous Cystadenoma (B) Mucinous Cystic Neoplasm (MCN) (C) Branch Duct IPMN (BD-IPMN) (D) Solid Pseudopapillary Tumour (SPT) (E) Pancreatic Adenocarcinoma

Correct Answer: (A) Serous Cystadenoma.

Explanation:

  • Why (A) is correct: This is the classic, pathognomonic description. Serous cystadenomas are benign cystic neoplasms, typically seen in elderly women. The hallmarks are the microcystic (“honeycomb”) pattern and the central stellate scar with sunburst calcification. They do not communicate with the pancreatic duct.
  • Why (B) is wrong: MCNs are macrocystic (large cysts), lack a central scar, occur in middle-aged women, and are pre-malignant.
  • Why (C) is wrong: BD-IPMNs are clusters of cysts that do communicate with the duct.
  • Why (D) is wrong: SPTs are complex, solid and cystic tumours seen in young women.
  • Why (E) is wrong: Adenocarcinoma is a solid, infiltrative, hypovascular mass.

Key Points: Serous Cystadenoma

  • Definition: A benign cystic neoplasm (“grandmother” lesion).
  • Demographic: Typically elderly women (>60).
  • Imaging (Pathognomonic):
    1. Microcystic (“Honeycomb”) Pattern: Cluster of innumerable tiny cysts.
    2. Central Stellate Scar with Sunburst Calcification.
  • Note: Benign, usually requires no treatment unless symptomatic.

Question 8: Mucinous Cystic Neoplasm (MCN)

Stem: A 45-year-old woman has an incidental finding on MRI. There is a 7 cm, well-defined, multiloculated macrocystic lesion in the tail of the pancreas. The cyst has thick septations and peripheral “egg-shell” calcification in its wall. It does not communicate with the pancreatic duct.

Question: This appearance and location are most characteristic of:

(A) Serous Cystadenoma (B) Mucinous Cystic Neoplasm (MCN) (C) Branch Duct IPMN (BD-IPMN) (D) Pancreatic Pseudocyst (E) Lymphangioma

Correct Answer: (B) Mucinous Cystic Neoplasm (MCN).

Explanation:

  • Why (B) is correct: This is the classic MCN (“mother” lesion). The key features are: 1) Middle-aged female, 2) Location in the pancreatic body or tail, 3) Macrocystic appearance (unilocular or few large locules), 4) No communication with the pancreatic duct, and 5) Often has peripheral egg-shell calcification. MCNs are considered pre-malignant.
  • Why (A) is wrong: Serous cystadenomas are microcystic with a central scar.
  • Why (C) is wrong: BD-IPMNs do communicate with the duct and are typically clusters of smaller cysts.
  • Why (D) is wrong: A pseudocyst is a post-pancreatitis complication and is usually unilocular with a thin wall (unless infected).
  • Why (E) is wrong: Lymphangiomas are rare cystic lesions but do not have this classic demographic or calcification pattern.

Key Points: Mucinous Cystic Neoplasm (MCN)

  • Definition: A pre-malignant cystic neoplasm (“mother” lesion).
  • Demographic: Almost exclusively middle-aged females (95%).
  • Location: Almost always pancreatic body or tail (95%).
  • Imaging:
    • Macrocystic (uni- or multilocular).
    • NO communication with the pancreatic duct.
    • Peripheral “egg-shell” calcification is highly suggestive.
  • Note: Usually resected due to malignant potential.

Question 9: Autoimmune Pancreatitis (AIP)

Stem: A 65-year-old man presents with painless jaundice. A CT scan shows diffuse, sausage-like enlargement of the entire pancreas. The main pancreatic duct is narrowed and featureless, and there is a characteristic low-density “halo” or capsule surrounding the pancreas. Other findings include bilateral renal lesions and retroperitoneal fibrosis.

Question: This constellation of findings is most suggestive of:

(A) Acute Pancreatitis (B) Chronic Pancreatitis (C) Pancreatic Adenocarcinoma (D) Autoimmune Pancreatitis (AIP) (E) Pancreatic Lymphoma

Correct Answer: (D) Autoimmune Pancreatitis (AIP).

Explanation:

  • Why (D) is correct: This is the classic Type 1 AIP (part of IgG4-related systemic disease). The key features are: 1) Diffuse, “sausage-shaped” enlargement of the pancreas, 2) Loss of normal pancreatic lobulations, 3) A featureless, narrowed main duct (unlike the dilatation in chronic pancreatitis), and 4) A low-density peripheral “halo”. The association with other IgG4-related findings (renal lesions, retroperitoneal fibrosis, sclerosing cholangitis) confirms the diagnosis.
  • Why (A) is wrong: Acute pancreatitis causes oedema and fluid collections, not diffuse enlargement with a halo.
  • Why (B) is wrong: Chronic pancreatitis causes atrophy and calcifications.
  • Why (C) is wrong: Adenocarcinoma is a focal, infiltrative, hypodense mass.
  • Why (E) is wrong: Lymphoma can cause diffuse enlargement but typically does not have the halo or the associated IgG4 findings.

Key Points: Autoimmune Pancreatitis (AIP)

  • Type 1 (Common): Part of IgG4-related disease. Affects older men.
    • Imaging: Diffuse “sausage-shaped” enlargement, loss of lobulations, peripheral low-density “halo”, featureless narrowed MPD.
    • Associations: Other IgG4 disease (cholangitis, RPF, renal lesions).
  • Type 2: Pancreas-specific, associated with IBD. Affects younger patients. Imaging is less specific.
  • Treatment: Responds dramatically to steroids.

Question 10: Pancreas Divisum

Stem: A 30-year-old woman presents with recurrent episodes of acute pancreatitis, despite having no history of gallstones or alcohol abuse. An MRCP is performed. The images demonstrate that the main pancreatic duct (Wirsung) drains only the ventral pancreatic bud (uncinate process and inferior head) via the minor papilla, while the dorsal pancreatic duct drains the majority of the pancreas (body and tail) via the major papilla.

Question: This congenital anomaly is known as:

(A) Annular Pancreas (B) Pancreas Divisum (C) Ectopic Pancreas (D) Pancreatic Agenesis (E) Choledochal Cyst

Correct Answer: (B) Pancreas Divisum.

Explanation:

  • Why (B) is correct: Pancreas divisum is the most common congenital anomaly of the pancreas. It results from the failure of fusion of the dorsal and ventral pancreatic buds during embryogenesis. This means the bulk of the pancreas (dorsal bud origin) drains via the smaller, accessory duct of Santorini through the minor papilla. This relative stenosis is thought to predispose to recurrent pancreatitis. MRCP is the best way to visualise the ductal anatomy.
  • Why (A) is wrong: An annular pancreas is when the ventral bud encircles the duodenum, causing gastric outlet obstruction.
  • Why (C) is wrong: Ectopic pancreas is pancreatic tissue found outside the pancreas (e.g., in the stomach wall).
  • Why (D) is wrong: Agenesis is the absence of the pancreas.
  • Why (E) is wrong: This is a congenital dilatation of the bile duct.

Key Points: Pancreas Divisum

  • Most common pancreatic congenital anomaly.
  • Cause: Failure of fusion of the ventral and dorsal pancreatic ducts.
  • Anatomy: Bulk of pancreas (dorsal duct) drains via the minor papilla.
  • Clinical: Usually asymptomatic, but associated with recurrent acute pancreatitis.
  • Imaging: MRCP is diagnostic, showing the non-communicating ducts.

Question 11: Splenic Infarct

Stem: A 55-year-old man with atrial fibrillation presents with acute left upper quadrant pain. A contrast-enhanced CT scan shows a wedge-shaped, peripherally based area of low attenuation (non-enhancement) in the spleen.

Question: What is the most likely diagnosis?

(A) Splenic Abscess (B) Splenic Infarct (C) Splenic Haemangioma (D) Splenic Lymphoma (E) Splenic Laceration

Correct Answer: (B) Splenic Infarct.

Explanation:

  • Why (B) is correct: This is the classic appearance. A splenic infarct is caused by occlusion of a branch of the splenic artery (often embolic, e.g., from atrial fibrillation). This results in a wedge-shaped, peripherally based area of non-perfusion (non-enhancement).
  • Why (A) is wrong: An abscess is typically round or irregular, rim-enhancing, and associated with fever/sepsis.
  • Why (C) is wrong: A haemangioma is a benign vascular lesion that would enhance (often similarly to a liver haemangioma).
  • Why (D) is wrong: Lymphoma is typically a solid, hypovascular mass or diffuse infiltration, not a wedge-shaped non-enhancing area.
  • Why (E) is wrong: A laceration (from trauma) would be an irregular linear defect, often with associated haematoma.

Key Points: Splenic Infarct

  • Cause: Occlusion of the splenic artery or its branches. Most common cause is embolic (e.g., atrial fibrillation). Also seen in sickle cell disease, pancreatitis.
  • CT Appearance: Wedge-shaped, peripheral, low-attenuation (non-enhancing) area.
  • Note: Over time, infarcts shrink and scar down.

Question 12: Splenomegaly (Cause)

Stem: A 40-year-old man has a CT scan for vague abdominal symptoms, which reveals massive splenomegaly (craniocaudal length 25 cm). The scan also demonstrates extensive porto-systemic collateral varices and ascites, but the liver appears normal in size and morphology.

Question: Given the normal liver morphology, what is the most likely cause of the portal hypertension and splenomegaly?

(A) Cirrhosis (B) Budd-Chiari Syndrome (C) Portal Vein Thrombosis (D) Congestive Heart Failure (E) Myelofibrosis

Correct Answer: (C) Portal Vein Thrombosis.

Explanation:

  • Why (C) is correct: This describes pre-hepatic portal hypertension. The liver itself is normal, but there is a blockage before the liver (in the portal vein). This causes “back-pressure” leading to massive splenomegaly and varices.
  • Why (A) is wrong: Cirrhosis is the most common cause overall, but it is an intra-hepatic cause, and the liver would appear shrunken and nodular.
  • Why (B) is wrong: Budd-Chiari is a post-hepatic cause (hepatic vein thrombosis) and has a characteristic “nutmeg” liver appearance.
  • Why (D) is wrong: Congestive heart failure causes passive congestion of both the liver (hepatomegaly) and spleen, but not usually varices to this extent.
  • Why (E) is wrong: Myelofibrosis is a primary haematological cause of splenomegaly (due to extramedullary haematopoiesis), but it does not directly cause portal hypertension and varices.

Key Points: Causes of Portal Hypertension

  • Pre-hepatic: Portal Vein Thrombosis, Splenic Vein Thrombosis. (Liver is normal).
  • Intra-hepatic: Cirrhosis (most common cause), Schistosomiasis. (Liver is abnormal).
  • Post-hepatic: Budd-Chiari Syndrome, Congestive Heart Failure. (Liver is congested).

Question 13: Splenic Trauma

Stem: A 22-year-old man is involved in a motorcycle accident. A contrast-enhanced trauma CT scan reveals multiple linear and branching lacerations within the spleen, with contrast extravasation indicating active bleeding. The splenic capsule appears intact.

Question: According to the AAST splenic injury grading scale, active contrast extravasation automatically places the injury into at least which grade?

(A) Grade I (B) Grade II (C) Grade III (D) Grade IV (E) Grade V

Correct Answer: (D) Grade IV.

Explanation:

  • Why (D) is correct: The presence of active contrast extravasation (a “blush” or “jet” of contrast leaking out of a vessel) signifies ongoing bleeding and automatically upgrades a splenic injury to at least Grade IV according to the American Association for the Surgery of Trauma (AAST) scale. Grade IV also includes segmental/hilar vessel injuries or >25% devascularisation.
  • Why (A), (B), (C) are wrong: Grades I, II, and III represent progressively deeper lacerations or larger haematomas without active bleeding or major vascular injury.
    • Grade I: Subcapsular haematoma <10% or laceration <1cm deep.
    • Grade II: Haematoma 10-50% or laceration 1-3cm deep.
    • Grade III: Haematoma >50% or laceration >3cm deep, or involving trabecular vessels.
  • Why (E) is wrong: Grade V represents a shattered spleen or hilar vascular avulsion (complete devascularisation).

Key Points: AAST Splenic Injury Scale (Simplified)

  • Grade I-III: Based on size of haematoma / depth of laceration. No active bleed.
  • Grade IV: Active contrast extravasation, major vascular injury, or >25% devascularisation.
  • Grade V: Shattered spleen or hilar avulsion.

Question 14: Accessory Spleen (Splenunculus)

Stem: A 50-year-old woman undergoes a CT scan for an unrelated reason. A 1.5 cm, well-defined, round soft-tissue nodule is seen adjacent to the splenic hilum. The nodule demonstrates enhancement that is identical to the splenic parenchyma on all contrast phases.

Question: What is the most likely diagnosis?

(A) Accessory Spleen (Splenunculus) (B) Pancreatic Tail Tumour (C) Lymph Node (D) Adrenal Nodule (E) Gastric GIST

Correct Answer: (A) Accessory Spleen (Splenunculus).

Explanation:

  • Why (A) is correct: Accessory spleens (or splenunculi) are common congenital variants (10-30% of people). They are small nodules of normal splenic tissue located separate from the main spleen, most commonly near the splenic hilum. The key diagnostic feature is that they enhance exactly like the normal spleen on all contrast phases.
  • Why (B) is wrong: A pancreatic tumour would enhance differently (e.g., PNET hypervascular, adeno hypovascular) and would arise from the pancreas.
  • Why (C) is wrong: A lymph node would typically enhance less avidly than the spleen.
  • Why (D) is wrong: An adrenal nodule is located superior to the kidney, separate from the spleen.
  • Why (E) is wrong: A GIST would arise from the stomach wall and enhance avidly but not identically to the spleen.

Key Points: Accessory Spleen (Splenunculus)

  • Definition: Common congenital ectopic splenic tissue.
  • Location: Most common near the splenic hilum or along the splenorenal ligament.
  • Imaging Hallmark: Identical enhancement to the main spleen on all contrast phases (including the typical heterogeneous arterial phase enhancement).

Question 15: Splenic Lymphoma

Stem: A 68-year-old man with known non-Hodgkin’s lymphoma undergoes a staging PET-CT scan. The CT component shows massive splenomegaly. The spleen contains multiple, small (< 2 cm), ill-defined, low-attenuation nodules that do not enhance significantly. These nodules are intensely FDG-avid on the PET component.

Question: This pattern of splenic involvement is most characteristic of:

(A) Splenic Lymphoma (B) Splenic Metastases (C) Splenic Abscesses (D) Sarcoidosis (E) Gamna-Gandy Bodies

Correct Answer: (A) Splenic Lymphoma.

Explanation:

  • Why (A) is correct: This is a common pattern of splenic involvement by lymphoma. It can present as: 1) Diffuse infiltration (just splenomegaly), 2) Solitary large mass, or 3) Multiple, small, focal, hypodense (hypovascular) nodules, as seen here. The FDG-avidity confirms metabolic activity consistent with malignancy.
  • Why (B) is wrong: Splenic metastases are rare (melanoma, breast, lung). They are typically larger, better defined, and may enhance differently.
  • Why (C) is wrong: Abscesses would be rim-enhancing and the patient would be septic; they are not typically FDG-avid in this pattern unless actively infected.
  • Why (D) is wrong: Sarcoidosis can cause splenic nodules, but they are typically smaller, more well-defined granulomas, and usually not this intensely FDG-avid.
  • Why (E) is wrong: Gamna-Gandy bodies are tiny siderotic nodules (low signal on all MRI sequences) seen in portal hypertension, not enhancing, FDG-avid nodules.

Key Points: Splenic Lymphoma

  • Common site of extranodal involvement in lymphoma.
  • Imaging Patterns:
    1. Diffuse Infiltration: Homogeneous splenomegaly (most common).
    2. Multiple Focal Nodules: Small (<3cm), hypodense, hypovascular.
    3. Solitary Large Mass: Less common.
  • PET-CT: Highly sensitive for detecting involvement, as lymphoma is typically FDG-avid.
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