Abdominal mass resident survival guide

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Javaria Anwer M.D.[2]
Synonyms and keywords: abdominal lump resident survival guide

Overview

An abdominal mass is a vast entity in oncology. A ruptured abdominal aortic aneurysm and volvulus are life-threatening causes of abdominal mass.

Causes

Life Threatening Causes

Life-threatening causes include conditions that may result in death or permanent disability within 24 hours if left untreated. The life-threatening causes of an abdominal mass include:

• Abdominal aortic aneurysm, specifically ruptured abdominal aortic aneurysm.
  • Tenth most common cause of death in the Western world.
  • Total mortality is estimated to be 80–90 %.
  • The 2013 mortality rate of US population above 44 years of age was 2.5 per 100,000. The incidence is on the decrease for the past two decades after a plateau. (the mortality rates act as a surrogate of incidence).
• Volvulus

Common Causes

Common causes of an abdominal mass described below follow a descending order. The list is based on a retrospective study from Turkey among 45 adult patients who underwent surgery because of an intra-abdominal mass (between May 2010 and May 2017).

Benign pathologies

• Mesenteric cyst
• Endometriosis
• Hydatid cyst
• Fibroma
• Dystrophic calcification
• Aberrant pancreas
• Leiomyoma
• Pseudocyst

Malignant pathologies

• Gastrointestinal stromal tumor (GIST)
• Liposarcoma
• Ovarian tumor
• Chondrosarcoma
• Neuroendocrine tumor
• Malignt mesenchymal tumor
• Lymphoma
• Schwannoma
• The following chart illustrates the probable causes of an abdominal mass based on the location and salient features.

Causes of abdominal mass

Abdominal wall mass ❑ Primary tumors (WHO classification) ❑ Adipocytic tumors (lipoma, liposarcoma) ❑ Fibroblastic/myofibroblastic tumors (desmoid tumor) ❑ Nerve sheath tumors (schwannoma, neurofibroma) ❑ Hemangiomas ❑ Undifferentiated pleomorphic sarcomas ❑ Metastasis ❑ Tumor-like mass ❑ Endometriosis, abscess, hematoma ❑ Hernias (epigastric, umbilical, incisional, and spigelian)

Intra-abdominal/ retroperitoneal mass

Hepatic mass ❑ Hepatitis (infectious, DILI, alcoholic, NASH, autoimmune, Wilson's disease ❑ Storage diseases (glycogen storage disease, lysosomal storage disease, lipid storage disease, hemochromatosis) ❑ Tumors ❑ Primary Benign:adenoma, FNH ❑ Primary malignant:HCC, cholangiocarcinoma ❑ Metastatic: Hemangioma, lymphoma, myeloma and solid tumors. ❑ Cholestasis (PBC, PSC)

Splenic mass ❑ Infectious (IM, liver abscess, echinococcosis) ❑ Myeloproliferative (lymphomas and leukemias) ❑ Storage (Gaucher's, Niemann-Pick disease) ❑ Infiltrative:amyloidosis, sarcoidosis ❑ Miscellineous (PH, metastases (lung cancer or breast cancer, Felty's syndrome)

Gastrointestinal and Genitourinary mass ❑ Gastrointestinal ❑ Volvulus ❑ IBD ❑ Colon cancer ❑ Gastric cancer ❑ Cholecystitis ❑ Genitourinary system ❑ Bladder distension ❑ Ovarian cyst/ ovarian cancer ❑ Leiomyoma ❑ Ureteropelvic junction obstruction/ urinomas ❑ Testicular cancer

Pancreatic mass ❑ Pancreatic cyst ❑ Neoplastic (mucinous, serous, intraductal papillary, and solid pseudopapillary) ❑ Non-neoplastic (true, mucinous) ❑ Inflammatory (pseudocyst, acute fluid collection) ❑ Solid: ❑ Adenocarcinomas (ductal, bile duct, ampullar and duodenal) ❑ Pancreatic neuroendocrine tumors ❑ Others (lymphoma and metastasis)

Retroperitoneal mass (majority tumors are malignant)

Neoplastic ❑ Solid ❑ Lymphoma ❑ Hydronephrosis ❑ Leiomyosarcoma ❑ Germ cell tumors ❑ Liposarcoma/ sarcoma ❑ Renal cell carcinoma ❑ Abdominal Aortic Aneurysm(AAA) ❑ Cystic ❑ Cystadenoma/ cystadenocarcinoma ❑ Mature teratoma

Non-neoplastic ❑ Solid ❑ Extramedullary hematopoiesis ❑ Retroperitoneal fibrosis ❑ Erdheim-Chester disease ❑ Cystic ❑ Epidermoid cyst ❑ Non-pancreatic pseudocyst ❑ Lymphoceles, hematoma ❑ Bronchogenic cyst

Diagnosis and management of pulsatile abdominal mass

Shown below is an algorithm summarizing the diagnosis and management of a pulsatile abdominal mass.

Pulsatile abdominal mass ❑ History (such as associated pain, past medical, surgical history) ❑ Physical exam (such as location and extent of the mass, change in size) ❑ Risk factors for the development of Abdominal Aortic Aneurysm (AAA)

Assess hemodynamic stability

Unsable

Stable

❑ Airway, Breathing and Circulation (ABC) ❑ Clinical diagnosis of ruptured AAA considered if patient is/was a smoker, >60 years old, HTN history, an existing diagnosis of AAA, and abdominal/back pain. ❑ Immediate bedside aortic US ❑ Systolic BP >70 acceptable (permissive hypotension)

❑ Abdominal ultrasound scan (US) ❑ Abdominal US (100% Sn and Sp but visualization among 1-3% patients) ❑ CTA (after normal RFTs) serves as first line modality but gold standard to assess AAA in few cases

Emergency repair (open or endovascular) if expertise are available

Transfer to a facility with vascular specialist expertise

AAA not demonstrated

AAA demonstrated

Look for other possible causes on a CT scan ❑ Heart failure (hepatomegaly, portal hypertension, pulmonary edema, and contrast reflux into IVC and hepatic veins) ❑ Colonic diverticula with peri-colic inflammation and fluid collection ❑ Dilatation of renal pelvicalyceal systems, splenomegaly ❑ Tumors (distinct mass or diffuse organ infiltration, LAD, metastasis to other organs) ❑ Pancreatic pseudocyst (Large cyst/multiple cysts in and around the pancreas with calcifications maybe, splenic vein thrombosis, and pseudoaneurysms of splenic artery, bleeding into a pseudocyst

<5.5cm

≥5.5cm

No pain demonstrated Rupture risk < operative repair risk (1 year)

Pain is present Search for risk factors: female, smoker, height, age, HTN history or other causes

No Pain demonstrated Rupture risk > operative repair risk (1 year)

Pain is present High rupture risk

Other causes (low rupture risk)

No other causes (moderate-high risk of rupture)

Elective repair is considered

❑ RFTs ❑ Crt<2mg/dl=CTA ❑ Crt>2mg/dl or dye allergy=MRA

❑ Follow-up in 6M ❑ Repair of aneurysm if it grows >0.4cm/year or becomes symptomatic ❑ Patient education

❑ Unruptured AAA (moderate risk) ❑ Hyperattenuating crescent sign, >150% normal diameter of aorta, mural thrombus and calcification ❑ Consider elective repair

❑ Ruptured AAA ❑ Contrast extravasation, draped aorta sign, and retroperitoneal hematoma with perirenal and pararenal space extension. ❑ Emergency repair

Diagnosis and management of stable abdominal mass

The table illustrates common imaging findings and management of a stable abdominal mass.

Cause of abdominal mass	CT scan	Ultrasound	MRI	PET scan	Management
Hepatic cyst	Reserved for more complicated cases. For more information click here	Most useful initial test. Assess cyst size, type, location within the liver, type, and anatomic relations with surroundings. Follow-up with US only if cyst is >4 cm.			Rule out infection and malignancy before diagnosis. Fever + cyst= suspect pyogenic liver abscess/ other infection. Asymptomatic simple cyst: no treatment required. Symptomatic cyst: sclerotherapy/ wide unroofing surgery. Echinococcosis: anthelmintics/ and surgery), amebic liver abscess: metronidazole, pyogenic liver abscess: antibiotic + percutaneous drainage. Cystadenoma and cystadenocarcinoma: surgically removed/ lobectomy/partial hepatectomy.
Hemangiomas	Asymmetric peripheral enhancement on IV contrast (diagnostic potential). For more information click here.				Biopsy is NOT recommended due to bleeding risk. Majority of patients do not require intervention.
Hepatic adenomas	Well-circumscribed hypo-intense lesions. For more information click here.				Malignant potential and bleeding risk. D/C OCP may lead to involution. >4 cm adenoma requires surgical resection.
Hepatocellular carcinoma (HCC)	With IV contrast, diffuse enhancement with arterial phase contrast, and then washout during delayed venous images. For more information click here.				Resection (small single lesions, no/limited cirrhosis)/ liver transplant (advanced cirrhosis) but no extrahepatic disease. If a patient with cirrhosis presents with a >1cm liver mass, pursue a definitive diagnosis to rule out HCC. Non-surgical transarterial chemoembolization (TACE) and radiofrequency ablation (RFA). Sorafenib (tyrosine kinase inhibitor) if patient is not a candidate for resection/ transplant.
Focal nodular hyperplasia (FNH)	Well-circumscribed mass with central stellate scar. Hyperintense on arterial phase and isodense on venous phase (IV contrast). For more information click here.				Reassure and observe (no malignant potential)
Cholangiocarcinoma	Lesion occurs in the periphery of liver Primary staging: Higher Sn in detecting extrahepatic invasion and vascular involvement.		Modality of choice for diagnosis and staging		Surgical resection with negative margin.
Hepatic metastatsis	Hypo-intense on venous phase contrast. Does not reliably detect lesions <1 cm. For more information click here.			More Sn than CT and can detect lesions < 1 cm. T1 weighted hypointense and T2 weighted hyperintense images.	Surgical resection of hepatic metastases after appropriate selection based on survival benefit. Radiofrequency ablation if hepatic resection is not possible. A multidisciplinary approach is required.
Splenomegaly	Important in pre-operative planning for splenectomy via an open versus laparoscopic approach. CT volumetry measures the true size of an enlarged spleen, detects accessory splenic tissue.	Doppler can determine the splenic artery and splenic vein patency.			Splenectomy relieves symptoms and induces hyposplenism. OPSI is a life-threatening complication. click here to read more.
Cystic pancreatic mass	Serous cystic tumor: Hypervascular lesions with central scar, septations, and central/ sunburst calcification. Microcystic Honeycomb appearance. Intraductal papillary mucinous neoplasm (IPMN): Communicates with main- pancreatic duct, branch duct or both. Mucinous cystic neoplasm (MCN): Well encapsulated, circular, unilocular or septated cysts with wall calcifications. Solid pseudopapillary neoplasm (SPN): Large solid and cystic components, hemorrhage, necrosis and/without calcifications. A solid component in IPMN and MCN may suggest malignancy.				Esophageal US-guided FNA with cyst fluid analysis or ERCP for diagnosis. Non-neoplastic cysts and serous cystic tumor are removed only if symptomatic. IPMN communicating with the main duct/ symptomatic/ with malignancy suspician is resected. Other cases are monitored. MCN and SPN have a significant malignant potential and should be removed.
Solid pancreatic mass	Helps in diagnosis, staging, treatment planning and followup. Pancreatic Ductal Adenocarcinoma (PDA): CT with IV contrast is the initial test of choice. A hypodense lesion that disrupting normal architecture of the pancreas accompanied by pancreatic / CBD dilatation may be demonstrated. A “double-duct” sign may also be demonstrated. Acinar Cell Carcinoma (ACC): Solid or cystic mass is demonstrated. Pancreatic Neuroendocrine Tumor (PNET): CT must be obtained among all patients nonetheless. On IV contrast, hypervascular lesions on the arterial phase are demonstrated.	PDA:Endoscopic ultrasound (EUS)/ ERCP with tissue sampling are diagnostic tools. PNET: EUS > CT at locating the lesion and biopsy at the same time.	MRI can be utilised in place of CT.		PDA: Resectable pancreatic head PDA us treated with pancreaticoduodenectomy (Whipple procedure). For the body and tail distal pancreatectomy is performed. Chemotherapy and radiotherapy are administered and/or post surgery. ACC: Surgical resection. PNET: Serum hormone testing is the mainstay of management. Surgical resection is the primary method of treatment as majority of tumors have malignant potential. Additional medical therapy may be required.
Retroperitoneal sarcoma	Chest, abdomen and pelvis contrast-enhanced CT for diagnosis, staging, and ruling out metastatic disease.		Among cases of contrast allergy, pelvic involvement, and equivocal CT imaging findings MRI with gadolinium is utilised.	Not routinely used.	Image-guided percutaneous core needle biopsy is considered safe and helps guide treatment modalities and the extent of surgery. R0 surgical resection is a potentially curative treatment method.
Abdominal wall hernias		First line imaging technique. Demonstration of bowel contents confims the disease.			Conservative approach/ elastic binders. Emergency surgery: abdominal contents compression/ strangulation. Elective surgery: Symptomatic hernia/ patient preference.

Do's

• Start the assessment of a patient with an abdominal mass using the pneumonic "ABC:" airway, breathing and circulation, to identify an unstable patient.
• Taking careful history, and thorough physical examination are crucial to creating narrow differential diagnoses.
• Among females of childbearing age (average age 12 and 51 or start of menstrual cycle till menopause), pregnancy screening (usually a urine pregnancy test) should be performed before diagnostic radiation exposure or interventions such as fluoroscopy‐guided interventions.
• Order an ultrasound or MRI among pregnant females to avoid exposure to radiation.
• Perform a pelvic and testicular examination among patients with lower abdominal pain.
• Correlate the CD4 count in HIV positive patients with the most commonly occurring pathology.
• Abdominal aortic aneurysm and malignancy are more important considerations among patients above 50 years of age than for younger patients.
• Suspect ruptured abdominal aortic aneurysm in old patients presenting with a pulsating mass, associated abdominal pain and a history of tobacco use.
• CT angiography is the gold standard and imaging modality of choice for the evaluation of abdominal aortic aneurysm.
• Auscultate a tender/ painful abdomen before palpation.

Don'ts

• Do not perform a CT scan before performing RFTs of a patient.

References

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