Organ Variation Flashcards
How can the spleen vary?
Lobulation
Accessory spleen
Wandering spleen
Polysplenia
How does the spleen develop?
Develops in dorsal mesogastrium in week 5
Stomach rotates and carries spleen from midline to left
Rotation of mesogastrium forms splenorenal (lienorenal) ligament
What structure does the foetal spleen have?
Lobulated
What can remnants of the foetal spleen show as in adults?
Clefts
Grooves
What pathology can remnants of the foetal spleen resemble?
Splenic lacerations
If lobulations persist on the medial border of the spleen, where can they extend to?
Upper pole of left kidney
What is the typical size for an accessory spleen?
1-3cm
Where do accessory spleens develop?
In early peritoneal folds
Where are the most common sites for accessory spleens?
Hilum of spleen
Near tail of pancreas
Where else can an accessory spleen be found?
Near splenic vessels In tail of pancreas In gastrosplenic or lienorenal ligament Wall of stomach/bowel In mesentery Pelvis/scrotum
What is the prevalence of accessory spleens?
10%
What does an accessory spleen resemble on CT?
Lymph node
What is a potential benefit of an accessory spleen?
Valuable source of splenic tissue for patients with a ruptured primary spleen
What is the prevalence of a wandering/ectopic spleen?
0.5%
What is the aetiology of a wandering spleen?
Failures in gastrosplenic and lienorenal ligament development:
- Abnormally long splenic mesentery
- Abnormally mobile spleen
In what individuals is a wandering spleen most common?
Children
Women aged 20-40 years
How does a wandering spleen present?
Asymptomatic Splenic torsion: - Pain (variable) - May spontaneously de-twist Acute torsion: - Infarction - Capsule stretching
What did a case study by Gayar et al., (2001) show in relation to a wandering spleen?
26 year old female with abdominal pain: - Spleen in mid-abdomen 4 years later: - Spleen now in lower pelvis - Spleen adjacent to bladder and uterus
What laterality disorders can lungs display?
Left isomerism:
- Both lungs have the appearance and structure of an anatomically left lung
Right isomerism:
- Both lungs have the appearance and structure of an anatomically right lung
Within the lungs, what are lobar variations important in identification of?
Bronchopulmonary segments
What other general lung variations can be seen?
Accessory tissues
Variant fissures
In a study by Prakash et al., (2010), what were the findings regarding the transverse fissure?
Absent in 7.1%
Incomplete in 50%
In a study by Prakash et al., (2010), what were the findings regarding the oblique fissure?
Right: - Absent in 7.1% - Incomplete in 39.3% Left: - Absent in 10.7% - Incomplete in 35.7%
What did 1 of the 29 individuals in the cadaver study by Prakash et al., (2010) have?
A single lung filling entire thoracic cavity
What other features were seen as variants in the Prakash et al., (2010) study?
Accessory lobe in 27.2%
Supernumerary fissures in 35%
What variations did Eroje and Onyije, (2011) note regarding lobar variations?
Right lung:
- One with incomplete horizontal fissure
- One with absent horizontal fissure
What variation did Nene et al., (2010) note regarding lobar variations?
Left lung with an accessory fissure
How did Gonlugar et al., (2005) describe the embryonic origin of tracheobronchial tree variations?
Anomalies result in lung buds develop at atypical sites or to an inappropriate number:
- Failure of regression?
- Migration of additional mesenchyme?
How many bronchoscopies did Gonlugar et al., (2005) review?
2550
How many of the bronchoscopies examined by Gonlugar et al., (2005) displayed major tracheobronchial tree variations?
2.6% (67 patients)
What was the most common major tracheobronchial tree variation found by Gonlugar et al., (2005)?
Bifurcate pattern in right upper lobe:
- In 32 out of the 67 patients with variants (47.8%)
Where was the most common site for variation in the lungs noted by Gonlugar et al., (2005)?
Right upper lobe:
- 71.6%
In who are the variants noted by Gonlugar et al., (2005) most common?
In men:
- For all variants except one
What are some examples of right sided variations noted by Gonlugar et al., (2005)?
Tracheal (pre-eparterial) bronchus
Right upper lobe segments
Post-eparterial bronchus
Accessory cardiac bronchus
When does the liver primordium appear in utero?
In the middle of the 3rd week
What is the liver bud?
An outgrowth of endodermal epithelium in the distal foregut
What does the liver bud grow into? What does this structure also contribute to?
Septum transversum:
- A mesodermal plate between pericardial cavity and stalk of yolk sac
- Also contributes to diaphragm
How does the bile duct form?
As the liver bud continues to penetrate the septum transversum, the connection between the liver bud (hepatic diverticulum) and duodenum narrows
What forms the gallbladder and cystic duct?
A small ventral outgrowth from the bile duct
Where does the liver lie in situs inversus?
On the left
In isomerism (situs ambiguus), where do the liver and gallbladder lie?
Midline
What are the type 1 liver variations?
Defective:
- Agenesis
- Aplasia
- Hypoplasia
What are the type 2 liver variations?
Excessive:
- Accessory lobes
- Ectopic tissue
Is total liver agenesis serious?
Yes
Is partial liver agenesis serious?
Usually not
How does partial liver agenesis present?
Asymptomatic
Usually incidentally found during:
- Surgery
- Autopsy
What studies describe hypoplasia or agenesis of the left lobe of the liver?
Prithishkumar and Kanakasabapathy, 2010 (agenesis)
Belton and VanZandt, 1983 (total congenital absence)
What studies describe hypoplasia or agenesis of the right lobe of the liver?
Radin et al., 1987 (agenesis)
Inoue et al., 1997 (hypoplasia)
Describe the findings of the Belton and VanZandt, (1983) study?
70 year old female:
- Total absence of left lobe on laparotomy
43 year old male:
- Thought to have hepatomegaly on examination
- CT showed a transverse stomach (mimicked hepatomegaly) and no liver to left of gallbladder fossa
What were the variations noted in the 68 year old females cadaver in the case study by Prithishjumar and Kanakasabapathy, (2010)?
Total agenesis of left lobe up to falciform ligament 5 separate nodules around porta hepatis: - One attached to gallbladder - One attached to falciform ligament Right lobe: - Abnormal shape - Poorly defined inferior border Caudate lobe hypertrophy Thick connective tissue band to left of falciform ligament
What did histological analysis of the thick connective tissue band in the cadaver in the Prithishjumar and Kanakasabapathy, (2010) case study find?
Dense connective tissue
Small tubes
A few blood vessels
What did Prithishjumar and Kanakasabapathy, (2010) conclude the thick connective tissue band was? What did they determine this had caused?
A connective tissue remnant of septum transversum:
- Stopped development of portion of hepatic epithelial trabeculae in septum transversum mesenchyme
- This stopped left liver lobe development
How many cases of right lobe agenesis have been noted in literature? Since when?
19 since 1956
How did most of the reported cases of right lobe agenesis present?
Biliary tract disease
Portal hypertension
How many of the reported cases of right lobe of liver agenesis were incidental findings?
5
What imaging had the patients with incidental finding of right lobe agenesis undergone?
CT
USS
What were the incidental findings of the Radin et al., (1978) study?
5 patients with no right lobe of liver:
- Hypertrophy of other lobes
- 3 also had absent caudate lobes
- Gallbladders lay posterior to medial segment of left lobe (suprahepatic)
- Dilated bile ducts
What were the demographics of the Aktan et al., (2001) study between 1997-1999?
383 patients: - 190 males - 193 females 54 cadavers Ages 32-64 All with no hepatic or parenchyma abnormalities
What did some of the cadavers show in the Aktan et al., (2001) study?
There can be absence of lobes and fusion of lobes without pathological consequences
What did CTs of the patients in the Aktan et al., (2001) study show?
Absence of left or right lobes (partial or complete) may not result in pathology
What were the hepatic parenchyma variations seen in a case study by Saigusa et al., (2001)?
Left lobe: - Not entirely missing (hypoplastic) - No parenchyma - Membranous Right and left hepatic ducts both present
What were the vascular variations seen in the case study by Saigusa et al., (2001)?
Right, left and middle hepatic arteries present
Left branch of portal vein connected to venous and rough ligaments of liver
What organ was absent in the cadaver in the Saigusa et al., (2001) case study?
Gallbladder
What were the hypothesised aetiologies of the variations seen in the Saigusa et al., (2001) case study?
?Disgenesis of hepatic primordium
?Anomalous umbilical vein
?Embolism in/Insufficient growth of left branch of portal vein
?Disorganised nutrient supply
Describe case 1 in the study of livers by Lee et al., (2004).
75 year old female who died of pneumonia:
- Hypoplastic left lobe (cyst like; thick, scar-like walls)
- Dilated ducts and vessels within left lobe
Describe case 2 in the study of livers by Lee et al., (2004).
91 year old male who died of brain infarct:
- 3 ‘rugby-ball’ shaped masses of parenchyma formed hypoplastic left lobe
- Covered in peritoneum
Describe the demographics of the 31 cases in Japanese literature of agenesis and hypogenesis of the right lobe of liver. What does this imply?
82.7% aged over 50
44.8% ages over 70
Implies it is a latent anomaly:
- As only 8 had abnormal liver function
How did the patient in the case study by Inoue et al., (1997) present?
74 year old male with gastric cancer:
- Mass in epigastrium
What did imaging of the patient in the case study by Inoue et al., (1997) show?
USS:
- Large left lobe of liver (lateral segment)
- Small right lobe
- Small caudate lobe
Technetium 99m scintigraphy:
- Increased accumulation in left lobe (and spleen)
- Only slight accumulation in right lobe
What other findings were seen in the patient in the case study by Inoue et al., (1997)?
Ectopic dislocation of gallbladder Well-developed left hepatic artery Small right hepatic artery Normal parenchyma on biopsy of both lobes Portal hypertension
What is the incidence of ectopic or accessory hepatic tissues found during laparoscopy or autopsy?
0.5%
How did the patient in the Han and Soylu, (2009) case study present?
26 year old female:
- Dry cough
- Normal blood tests
What did imaging of the patient in the Han and Soylu, (2009) case study show?
CXR and CT chest showed accessory liver in thorax
How many cases of supradiaphragmatic liver have been reported?
17
What are the four main types of ectopic liver? (Reference?)
Type A = Liver not attached to main liver but attached to gallbladder/ligaments
Type B = Microscopic liver found in gallbladder
Type C = Large accessory liver attached to main liver by stalk
Type D = Small ectopic (10-30g) attached to liver by stalk (Christine et al., 2004)
What type of ectopic liver was seen in the Han and Soylu, (2009) case study?
Type C:
- Large accessory liver attached by vascular stalk
What might ectopic livers be related to?
Hepatocellular carcinoma development
Describe the case study by Parke et al., (1996)?
Found a large lobe weighing 165.4g hanging from left lobe of liver in a 93 year old female cadaver:
- Died of stroke
- Marginal lobe
What did Parke et al., (1996) find when they compared their case and marginal lobes in the literature to perinatal livers?
Discrepancies between adult and perinatal livers
Ectopic accessory lobes:
- Rare in adults
- Relatively common in perinatal livers (6/52 = 11.5%)
No marginal lobes in perinatal specimens
What other features of hepatic tissues are common in perinatal livers?
Gallbladder bridges of hepatic material (3/52) Accessory fissures (28/52)
How did Parke et al., (1996) describe the differences between perinatal and adult livers?
There is considerable non-uniform remodelling of the hepatic components
Many foetal variants disappear
Marginal lobes:
- Retention of original foetal boundary of anterior liver
What is a bifid liver?
Right and left lobes not connected
What is the incidence of a bifid liver?
0.005%
Describe the presentation of the patient in the case study by Nan and Lu-Nan, (2010)?
61 year old female with RUQ pain:
- Left lobe hepatolithiasis
- Underwent laparotomy
What did laparotomy of the patient in the case study by Nan and Lu-Nan, (2010) show?
2 lobes with median fissure
IVC visible under fibrous midline tissue
Size and shape of rest of liver and gallbladder normal
What did Nan and Lu-Nan propose could be the origin of the variation they noted?
Undefined embryological factors may result in connective tissue encapsulating the liver cell cord before fusion of the right and left lobes
From what germ layer do the kidneys develop from?
Intermediate mesoderm
What is the first kidney system to form in utero? Describe this system.
Pronephros:
- Very similar to fish kidney
- Forms in early 4th week
- Non-functioning
- Regresses completely
What is the second kidney system to form in utero? Describe this system.
Mesonephros:
- Derived from intermediate mesoderm in upper thoracic to upper lumbar segments
- Form in late week 4
- Well developed
- Functions until mid- month 2 then regresses
- Some caudal tubes remain in the genital system of males
What is the third kidney system to form in utero? Describe this system.
Metanephros:
- Primordia of permanent kidney
- Develops from metanephric mesoderm in week 5
- Functional by week 9
Where does the metanephric kidney lie initially?
Pelvis
When does the primordial kidney reach adult position?
Week 9
How does the kidney reach its abdominal adult position?
Ascent is relative due to growth of tissues caudal to the kidneys:
- Pelvis moves away from kidneys
Where do the kidneys lie in the adult?
Retroperitoneum
What is the orientation of the hilum of the kidney throughout development?
Initially ventral-facing
Rotates:
- Almost 90 degrees
- Faces anteromedially by week 9
What are the kidney variations that MacDonald Brown read to the anatomical section of the BMA in 1893?
I = Kidneys normal in position and size; altered in form II = Kidneys normal in position; altered in relative size III = Variations in number IV = Variations in position V = Malformations VI = Variation of ureters VII = Vascular abnormalities
What percentage of all congenital abnormalities do urogenital variations make up?
33%
What is the rarest urogenital variation?
Supernumerary kidney:
- First described in 1656
- 80 cases reported so far
What causes a supernumerary kidney?
Secondary outpouching of Wolffian (mesonephric) duct
OR
Initial ureteral bud variations:
- Bifurcation of ureteral bud and individual penetration of both branches into metanephrogenic blastema
- Two initial ureteral buds
What can supernumerary kidney be associated with?
Other urogenital abnormalities
What are the 3 forms of supernumerary kidney?
Encapsulated
Totally separate from original kidney
Connected to original kidney by a connective tissue sheath
How did the patient in the case study by Ozturk et al., (2007) present?
39 year old female:
- Pain in right lower quadrant
- UTI
What did imaging of the patient in the case study by Ozturk et al., (2007) show?
USS:
- Suspicious mass in pelvis
CT:
- 2 functioning kidneys in normal positions
- 3rd functioning kidney in right iliac fossa
How was the patient in the case study by Ozturk et al., (2007) treated?
Antibiotics for UTI
Diclofenac (anti-inflammatory) for pain
How did the patient in the case study by Kusuma et al., (2005) present?
36 year old male:
- Painful swelling in left inguinal region
- 1 month duration
- 4cm x 5cm swelling
What did examination and abdominal imaging of the patient in the case study by Kusuma et al., (2005) show?
Examination: - Left scrotum empty Abdominal scan: - Normal - 2 normal kidneys
What was the initial diagnosis of the patient in the case study by Kusuma et al., (2005)?
Indirect inguinal hernia
Undescended left testis
What was found during surgery of the patient in the case study by Kusuma et al., (2005)?
Hernial sac contained undescending testis plus small bean-shaped mass:
- 3cm x 2cm x 2cm
What did histological analysis of the mass show in the case study by Kusuma et al., (2005)?
Cortex and medulla with glomeruli and tubules in developmental stages
How did the patient in a case study by Favorito and Morais, (2012) present?
27 year old female with 3 days history of:
- Left flank pain
- Fever
Diagnosed with UTI
What did a MRI scan of the patient in a case study by Favorito and Morais, (2012) show?
Supernumerary kidney:
- Fused at superior pole to inferior pole of left kidney
- Both it and the normal left kidney had separate collecting systems and ureters
How was the patient in the in a case study by Favorito and Morais, (2012) treated?
Antibiotics for UTI
How did the patient in the Floyd et al., (2012) case study present?
45 year old male with sciatica
What did an MRI of the patient in the Floyd et al., (2012) case study show?
Mass in abdomen Absence of right kidney Dilated: - Right blind-ending ureter - Right seminal vesicle
How does renal agenesis arise?
Ureteral bud fails to develop and hence there is no induction of the metanephric tissue to form the metanephric blastema
What is the incidence of horseshoe kidneys in cadavers?
1 in 400
What is the male:female ratio of horseshoe kidneys?
2:1
What pathology is horseshoe kidney often associated with?
Renal calculi
Describe the structure of the kidney in the 40 year old cadaver in a case study by Ongeti et al., (2011)?
Retroperitoneal horseshoe kidney:
- Kidneys united with bridge at L2
- Kidneys fused at inferior poles just before IMA
Describe the partial duplex system of the horseshoe kidney in the case study by Ongeti et al., (2011)?
Each kidney had:
- 2 ureters which fused at lower pole of each kidney
- A superior and inferior renal artery
Only the right kidney had 2 renal veins
What would have made a complete duplex system in the case study by Ongeti et al., (2011)?
The left kidney also having 2 renal veins instead of just 1
When was the first transplantation of a horseshoe kidney?
1975 by Nelson and Palmer
Why might a horseshoe kidney be used for transplant?
Shortage of donor organs
What makes horseshoe kidney transplants more difficult?
Vessel variations
What type of transplant is carried out if the urinary collection system of a horseshoe kidney is in the midline?
En bloc
How is a horseshoe transplant surgery carried out if the urinary collecting systems are separate?
Divide horseshoe kidney at isthmus
Describe the kidney transplant operation carried out by Salehipour et al., (2007)?
Donor kidney was horseshoe Each side: - 2 arteries - 1 vein - 1 ureter Kidney removed en bloc and split at isthmus: - Into 2 recipients
How did the patient present in a case study by Ramasamay et al., (2009)?
10 year old boy:
- Fever
- Lower limb swelling
- Passing little urine
- Suprapubic mass
- Undescended left testis
What variation caused the presentation in a case study by Ramasamay et al., (2009)?
Hydronephrotic pelvic kidney (1L of pus removed)
Horseshoe kidney:
- Right side functioning
- Left side non-functioning
What was seen during surgery of the patient in a case study by Ramasamay et al., (2009)?
Right side of horseshoe drained into ureter:
- Joined by supernumerary pelvic kidney’s ureter
How did the patient in the Mustafa, (2012) study present?
63 year old male with persistent mild abdominal pain
What did an IV pyelogram and CT show in the study by Mustafa, (2012)?
2 left malrotated kidneys: - 2 separate collecting systems - 1 ureter 2 right unified ectopic kidneys: - Separate collecting systems - Horseshoe isthmus - In lower mid-abdomen
What are pelvic kidneys?
Kidneys that do not ascend
What are more common, thoracic or pelvic kidneys?
Pelvic kidneys
What are ectopic kidneys associated with?
Obstruction
Infection
Calculi formation
What are thoracic kidneys?
Kidneys that ascend too far
What is the incidence of thoracic kidneys in cadavers?
1 in 13,000 autopsies
What percentage of ectopic kidneys are thoracic?
5%
What are the two types of thoracic kidneys?
Totally in thorax
Within diaphragmatic defect capped with fibrous connective tissue
What did Govindarajan and Meenashisundaram, (2011) discover on the dissection of a 73 year old male cadaver?
Right kidney lying between L4 and S2:
- Superior polar artery and right renal artery from left side of abdominal aorta at L4
- Renal vein from superior pole to IVC
- Renal vein from hilum to left suprarenal vein then to left renal vein
What is a pancake kidney?
Pelvic kidney
Both kidneys fail to ascend and remain in pelvis
Limited space so kidneys fuse into one lump
Describe the vasculature to the pancake kidney of a 70 year old male in a study by Eckes and Lawrence, (1997)?
Right and left renal arteries to pancake kidney arose from the right and left common iliac arteries respectively
A small aortic branch supplied the middle section of the pancake kidney
Why was the patient scanned in the case study by Eckes and Lawrence, (1997)?
To plan bilateral common iliac artery reconstruction:
- Patient had an aneurysm of the left common iliac artery from USS
How did the patient in the case study by Dogra, (1999) present?
20 year old male:
- Abdominal mass
- Abdominal pain
- Reduced urine output
What were the causes of the patient presentation in the case study by Dogra, (1999)?
Multiple calculi:
- Obstruction and renal failure
What was the variation causing the patient’s pathology in the case study by Dogra, (1999)?
Left to right crossed ectopic kidney:
- The left kidney had NOT fused to right kidney
What percentage of crossed kidneys remain unfused?
10%
What was the outcome of the patient in the case study by Dogra, (1999)?
Stones were cleared and he recovered
How do thoracic ectopic kidneys usually present?
Asymptomatic
What did an abdominal USS of a 38 year old male by Mensah and Forson, (2010) show?
?Small right kidney
What did IV urography in the case study by Mensah and Forson, (2010) show?
Right kidney in abdomen
Left kidney in thorax:
- Normal size
- Malrotated
- Normal left adrenal gland
- Ureter through left hemidiaphragm to bladder
- Renal artery from L1 through hemidiaphragm
What was the patient in the Liddell et al., (1989) study undergoing CXRs?
Required surgery to band the pulmonary artery due to worsening congestive heart failure
Who was the patient in the Liddell et al., (1989) case study?
A 6 month year old boy with Down’s syndrome
What did the pre-op CXR of the patient in the Liddell et al, (1989) case study show?
Bilateral thoracic masses:
- Found to be kidneys on USS
Following CXR at age 6 months, what previous scans were reviewed in the Liddell et al., (1989) case study and what did they show?
Neonatal CXR and abdominal USS;
- Kidneys in normal position at that time
What was the defect in the diaphragm capped by in the patient in the Liddell et al., (1989) case study?
Connective tissue
How many people have 2-4 renal arteries to each kidney?
25%
Where do extra renal arteries usually arise and enter the kidney?
Usually from aorta
Often don’t enter at hilum
What can happen if extra renal arteries cross the ureter?
Hydronephrosis if causing obstruction
Why can damaged accessory renal arteries result in ischaemic areas?
They are end arteries
How much more common are accessory renal arteries than accessory renal veins?
Almost twice as common
What variations were seen in the case study by Rakesh et al., (2008)?
60 year old cadaver:
- Right kidney pyramidal shape with anteriorly-facing hilum
- Right renal artery twisted around right renal vein
- IVC kinked to right
Left kidney:
- 2 renal arteries
- 1 renal vein
