Pheochromocytoma

PHEOCHROMOCYTOMA

Q. 1

Percentage of pheochromocytoma that are bilateral is:

 A

<1%

 B

1-5%

 C

10%

 D

25%

Q. 1

Percentage of pheochromocytoma that are bilateral is:

 A

<1%

 B

1-5%

 C

10%

 D

25%

Ans. C

Explanation:

Pheochromocytomas often are called the 10 percent tumor because 10% are bilateral, 10% are malignant, 10% occur in pediatric patients, 10% are extra-adrenal, and 10% are familial.
Ref: Schwartz’s principle of surgery 9th edition, chapter 38.

Q. 2

How will you localize pheochromocytoma :

 A

Clinical examination

 B

VMA excretion

 C

CT scan

 D

X-ray

Q. 2

How will you localize pheochromocytoma :

 A

Clinical examination

 B

VMA excretion

 C

CT scan

 D

X-ray

Ans. C

Explanation:

Radiologic studies are useful to localize Pheochromocytoma and to assess the extent of spread once the diagnosis has been made with biochemical tests.
CT scans are 85 to 95% sensitive and 70 to 100% specific for pheochromocytomas.
CT scans do not provide functional information and cannot definitively diagnose pheochromocytomas.
MRI scans are 95% sensitive and almost 100% specific for pheochromocytomas because these tumors have a characteristic appearance on T2-weighted images or after gadolinium.
MRI is also the study of choice in pregnant women as there is no risk of radiation exposure.
 
Ref : Lal G. (2010). Chapter 38. Thyroid, Parathyroid, and Adrenal. In T.R. Billiar, D.L. Dunn (Eds), Schwartz’s Principles of Surgery, 9e.

Q. 3

All of the following are features of pheochromocytoma except:

 A

Hypertensive paroxysm

 B

Headache

 C

Orthostatic hypotension

 D

Wheezing

Q. 3

All of the following are features of pheochromocytoma except:

 A

Hypertensive paroxysm

 B

Headache

 C

Orthostatic hypotension

 D

Wheezing

Ans. D

Explanation:

Clinical features of pheochromocytoma includes: Hypertension (usually paroxysmal; often postural drop of blood pressure), attacks with Pallor (occasionally flushing), palpitations, sweating, headache and anxiety, abdominal pain, vomiting, constipation, weight loss and glucose intolerance.

Ref: Harrisons Internal Medicine, 18th Edition, Chapter 343 ; Current Medical Diagnosis and Treatment, 2012, Chapter 26

Quiz In Between


Q. 4

All are true about pheochromocytoma, except:

 A

90% are malignant

 B

95% occur in the abdomen

 C

They secrete catecholamines

 D

They arise from sympathetic ganglions

Q. 4

All are true about pheochromocytoma, except:

 A

90% are malignant

 B

95% occur in the abdomen

 C

They secrete catecholamines

 D

They arise from sympathetic ganglions

Ans. A

Explanation:

Pheochromocytoma may occur as a single tumor or as more than one growth.

It usually develops in the center (medulla) of one or bothadrenal glands.

Rarely, this kind of tumor occurs outside the adrenal gland, usually somewhere else in the abdomen.Very few pheochromocytomas are cancerous around 10%.
The tumors may occur at any age, but they are most common from early to mid-adulthood.

Pheochromocytoma follows a rough rule of tens –
10% cases are not associated with hypertension
10% are extra – adrenal and of those 10% are extra – abdominal
10% cases occur in children
10% cases affect both adrenals
10% cases have metastatic potential (malignant)

Ref: CMDT 2008 Edition, Page 1012


Q. 5

Pheochromocytoma does not arise from which of the following –

 A

Adrenal medulla

 B

Adrenal cortex

 C

Extra adrenal sites

 D

Sympathetic chain

Q. 5

Pheochromocytoma does not arise from which of the following –

 A

Adrenal medulla

 B

Adrenal cortex

 C

Extra adrenal sites

 D

Sympathetic chain

Ans. B

Explanation:

Ans. is ‘b’ i.e., Adrenal cortex

Pheochromocytoma

o Pheochromocytoma is a neoplasm of chromaffin cells which usually arise from adrenal medulla. o About 10% of these tumors arise at extraadrenal sites, where they are called paraganglioma :-

i)         Paravertebral paraganglia (organs of zuckerkandl ) Have sympathetic connection.

ii)       Carotid bodies (chemodectomas).


Q. 6

The diagnostic procedure not done in case of pheochromocytoma.

 A

CT scan

 B

MRI

 C

FNAC

 D

MIBG scan

Q. 6

The diagnostic procedure not done in case of pheochromocytoma.

 A

CT scan

 B

MRI

 C

FNAC

 D

MIBG scan

Ans. C

Explanation:

C i.e. FNAC

  • Due to risk of catastrophic hypertensive crisis and fatal cardiac arrhythmia, fine needle aspiration cytology (FNAc) of pheochromocytoma is contraindicatedQ.
  • Injection of intravenous contrast dye or glucagon, anesthesia and surgical procedure can also trigger the catestrophic crisis.
  • The diagnosis is based on demonstration of catecholamine excess by biochemical tests and localization of tumor by
    imaging (CT, Gadolinium MRI, 1131 or 1123 MIBG, Somatostatin analogues scintigraphy or F18 dopamine PET)
  • Plasma – catecholamines, free metanephrins; & chromogranin A and urinary (24 hour) vanillyl mandelic acid, catecholamines, fractioned & total metanephrines are elevated on biochemical testing.

Quiz In Between


Q. 7

Commonest symptom of pheochromocytoma is

 A

Palpitation

 B

Headache

 C

Sweating

 D

Dyspnoea

Q. 7

Commonest symptom of pheochromocytoma is

 A

Palpitation

 B

Headache

 C

Sweating

 D

Dyspnoea

Ans. B

Explanation:

Ans. is ‘b’ i.e., Headache 

Hypertension is the most common symptom of pheochromocytoma followed by headache > Sweating > Palpitation.


Q. 8

False statement about pheochromocytoma –

 A

10% are bilateral

 B

Arises from chromaffin cells

 C

Extra adrenal tumor -increased nor adrenaline levels

 D

None

Q. 8

False statement about pheochromocytoma –

 A

10% are bilateral

 B

Arises from chromaffin cells

 C

Extra adrenal tumor -increased nor adrenaline levels

 D

None

Ans. D

Explanation:

Ans. is ‘None’ 


Q. 9

Pancreatitis, pituitary tumor and pheochromocytoma may be associated with:

 A

Medullary carcinoma of the thyroid

 B

Papillary carcinoma of the thyroid

 C

Anaplastic carcinoma of the thyroid

 D

Follicular carcinoma of the thyroid

Q. 9

Pancreatitis, pituitary tumor and pheochromocytoma may be associated with:

 A

Medullary carcinoma of the thyroid

 B

Papillary carcinoma of the thyroid

 C

Anaplastic carcinoma of the thyroid

 D

Follicular carcinoma of the thyroid

Ans. A

Explanation:

Answer is A (Medullary Carcinoma of Thyroid);

Out of all the histological variants of carcinoma thyroid it is the medullary variant that is associated with multiple endocrinal neoplastic syndromes and hence is the answer here.

(No confusion regarding the answer)

What puzzles the situation? is the fact that the combination of pancreatitis, pituitary tumor and pheochromocytoma, suggests a diagnosis of MENI syndrome. MEN I has been mentioned to be associated with C cell hyperplasia, and not Medullary carcinoma thyroid. Medullary thyroid carcinomas is a feature of MEN II syndromes.

Justification: Medullary carcinoma thyroid arises from parafollicular C cells. C cell hyperplasia thus, may be regarded as a precursor of Medullary carcinoma thyroid.

If present in the options, C cell hyperplasia would have been a more correct answer, however in its absence, Medullary thyroid carcinoma is certainly the option of choice

MEN SYNDROMES (Broad Perspective)

MEN I (WERMER’S)

MEN II

Characterized by tumors of

Characterized by association of

1.    Parathyroid

–  Medullary carcinoma thyroid &

2.    Pituitary

– Pheochromocytoma

3.    Pancreatic islet cells

Zollinger Ellison syndrome (gastrin)

 

II A (Sipple syndrome)

[I B

Insulinoma (Insulin)

When associated with hyper-

When associated with mucosal

Glucagonoma (Glucagen)

parathyroidism

neuromas and marfinoid habitus

Verner morrison or watery diarrhea

syndrome (pancreatic cholera)

 

 

 

Quiz In Between


Q. 10

Pheochromocytomas arise from:

 A

Nonendocrine cells of the adrenal cortex

 B

Nonendocrine cells of the adrenal medulla

 C

Neuroendocrine cells of the adrenal cortex

 D

Neuroendocrine cells of the adrenal medulla

Q. 10

Pheochromocytomas arise from:

 A

Nonendocrine cells of the adrenal cortex

 B

Nonendocrine cells of the adrenal medulla

 C

Neuroendocrine cells of the adrenal cortex

 D

Neuroendocrine cells of the adrenal medulla

Ans. D

Explanation:

Answer is D (Neuroendocrine cells of the adrenal medulla):

Pheochromocytomas are catecholamine secreting tumors that arise from neuroendocrine chromaffin tissue in the adrenal medulla.

  • The adrenal medulla consists of neuroendocrine cells called chromaffin cells
  • Chromaffin cells are derived from primitive pheochromblasts of the developing sympathetic nervous system.
  • Chromaffin cells are the site of catecholamine biosynthesis
  • Pheochromocytomas arise from chromaffin cells in the adrenal medulla
  • Most pheochromocytomas secrete both norepinephrine and epinephrine
  • The percentage of norepinephrine is usually greater than epinephrine (Often as high as 20:1)

Most Extra-adrenal pheochromocytomas (paragangliomas) secrete norepinephrine exclusively


Q. 11

Extraadrenal Pheochromocytoma predominantly secretes:

 A

Epinephrine

 B

Norepinephrine

 C

Dopamine

 D

DOPA

Q. 11

Extraadrenal Pheochromocytoma predominantly secretes:

 A

Epinephrine

 B

Norepinephrine

 C

Dopamine

 D

DOPA

Ans. B

Explanation:

Answer is B (Norepinephrine):

Most extraadrenal pheochromocytomas secrete norepinephrine exclusively

Most pheochromocytomas produce both norepinephrine and epinephrine and the percentage of norepinephrine is usually greater than in normal adrenal.

Most Extraadrenal pheochromocytoma secrete norepinephrine exclusively.

Pheochromocytomas in association with MEN may rarely produce epinephrine alone.


Q. 12

Investigation of choice in pheochromocytoma is:

 A

CT scan

 B

Urinary catecholamines

 C

MIBG scan

 D

MRI Scan

Q. 12

Investigation of choice in pheochromocytoma is:

 A

CT scan

 B

Urinary catecholamines

 C

MIBG scan

 D

MRI Scan

Ans. B

Explanation:

Answer is B (Urinary Catecholamines):

Pheochromocytomas synthesize and store catecholamines which include norepinephrine, epinephrine and dopamine. The investigation of choice for diagnosis of Pheochromocytomas is determination of elevated levels of catecholamines and their methylated metabolites (metanephrines) in the plasma and urine.

CT scan, MRI and MBIG Scintography are all useful diagnostic modalities for localization  of pheochromocytoma once the diagnosis is established.

Quiz In Between


Q. 13

All of the following are increased in pheochromocytomas. except

 A

Vinyl Mandelic Acid (VMA)

 B

Metanephrines

 C

5HIAA

 D

Catecholamines

Q. 13

All of the following are increased in pheochromocytomas. except

 A

Vinyl Mandelic Acid (VMA)

 B

Metanephrines

 C

5HIAA

 D

Catecholamines

Ans. C

Explanation:

Answer is C (5HIAA):

SHIAA levels are elevated in carcinoid syndrome and not in pheochromocytoma.

Pheochromocytomas (and paragangliomas)

  • Pheochromocytomas and paragangliomas synthesize and store catecholamines which include norepinephrine (noradrenaline), epinephrine (adrenaline) and dopamine
  • Pheochromocytomas are typically associated with elevated levels of plasma and urinary catecholamines and their metabolites such as VMA and metanephrines
  • The most sensitive test for diagnosis ofpheachromocytomas is measurement of fractionated metanephrines in urine and free metanephrine in plasma.

Q. 14

Pheochromocytomas are known to arise from all of the following, except:

 A

Adrenal gland

 B

Mediastinum

 C

Neck

 D

Chest wall

Q. 14

Pheochromocytomas are known to arise from all of the following, except:

 A

Adrenal gland

 B

Mediastinum

 C

Neck

 D

Chest wall

Ans. D

Explanation:

Answer is D (Chest wall):

Pheochromocytomas are not found in the chest wall
Pheochromocytomas may be found in the adrenal gland, neck and mediastinum (along the sympathetic chain), abdomen (paraaortic) and urinary bladder.

Sites of pheochromocytoma

  • Adrenal gland (most common)
  • Head and Neck
  • Thorax (mediastinum)
  • Intra abdominal (paraaortic)
  • Bladder

Q. 15

Classic Triad of Pheochromocytoma includes episodes of all of the following Except:

 A

Palpitation

 B

Headache

 C

Sweating

 D

Hypertension

Q. 15

Classic Triad of Pheochromocytoma includes episodes of all of the following Except:

 A

Palpitation

 B

Headache

 C

Sweating

 D

Hypertension

Ans. D

Explanation:

Answer is D (Hypertension):

The classic triad of pheochromocytoma includes episodes of palpitations, headaches and profuse sweating

Among the presenting symptoms, episodes of palpitations, headache and profuse sweating are typical and constitute the classic triad. The presence of all three symptoms of the classic triad in association with hypertension makes pheochromocytoma a likely diagnosis’ – Harrison

Quiz In Between


Q. 16

All are clinical features of pheochromocytoma, except :

 A

Increased hematocrit

 B

Orthostatic hypotension

 C

Low cortisol level

 D

Impaired glucose tolerance

Q. 16

All are clinical features of pheochromocytoma, except :

 A

Increased hematocrit

 B

Orthostatic hypotension

 C

Low cortisol level

 D

Impaired glucose tolerance

Ans. C

Explanation:

Answer is C (Low cortisol level)

Pheochromocytoma is not associated with low cortisol levels.

  • Pheochromocytoma is unique in presentation as it may present both with, Hypertension and hypotension.
  • Hypertension occurs in paroxysms and is the most common manifestation

    – Hypotension occurs as `orthostatic hypotension’ and it occurs as a consequence of diminished plasma volume and blunted sympathetic reflexes.

    Carbohydrate intolerance: Over half of patients have impaired carbohydrate tolerance due to suppression of insulin and stimulation of hepatic glucose output.

    Hematocrit: An elevated hematocrit may be secondary to diminished plasma volume.

     


Q. 17

All of the following are seen in pheochromocytoma. Except

 A

Headache

 B

Sweating episodes

 C

Weight loss

 D

Hypocalcemia

Q. 17

All of the following are seen in pheochromocytoma. Except

 A

Headache

 B

Sweating episodes

 C

Weight loss

 D

Hypocalcemia

Ans. D

Explanation:

Answer is D (Hypocalcemia):

Pheochromacytomas may be associated with hypercakemia and are not associated with hypocalcemia.

Clinical Features Associated with Pheochromocytoma

  • Headaches
  • Sweating attacks
  • Palpitations and tachycardia
  • Hypertension, sustained or paroxysmal
  • Anxiety and panic attacks
  • Pallor
  • Nausea
  • Abdominal pain
  • Weakness
  • Weight loss
  • Paradoxical response to antihypertensive drugs
  • Polyuria and polydipsia
  • Constipation
  • Orthostatic hypotension
  • Dilated cardiomyopathy
  • Erythrocytosis
  • Elevated blood sugar
  • Hypercalcemia

Q. 18

The predominant symptom/sign of pheochromocytoma is:

 A

Sweating

 B

Weight loss

 C

Orthostatic hypotension

 D

Episodic hypertension

Q. 18

The predominant symptom/sign of pheochromocytoma is:

 A

Sweating

 B

Weight loss

 C

Orthostatic hypotension

 D

Episodic hypertension

Ans. D

Explanation:

Answer is D (Episodic Hypertension):

The predominant manifestation of Pheochromocytoma is Hypertension which classically presents as Episodic Hypertension (Sustained Hypertension and Orthostatic Hypotension may also be seen).

‘The dominant sign is Hypertension. Classically patients have episodic hypertension, but sustained hypertension is also common’ – Harrison

Quiz In Between


Q. 19

Most common paroxysmal symptom of pheochromocytoma:

 A

Headache

 B

Palpitation

 C

Abdominal pain

 D

Hypotension

Q. 19

Most common paroxysmal symptom of pheochromocytoma:

 A

Headache

 B

Palpitation

 C

Abdominal pain

 D

Hypotension

Ans. A

Explanation:

Answer is A (Headache):

The single most common paroxysmal symptom  reported in patients with pheochromocytoma is headache

‘Most adult patients have paroxysmal symptoms, lasting minutes to hours, consisting of headache (80%), perspiration (70%), and palpitations (60%)’ – Endocrine Tumors (PMPH-USA, 2003)/ 104

The three most commonly reported paroxysmal symptoms in pheochromocytoma are Headache, Palpitations and Excessive or inappropriate sweating. Almost all patients will have one of three symptoms above and most will have at least two.

The most common and predominant sign of Pheochromocytoma is Hypertension


Q. 20

Dose of clonidine in suppression test done for pheochromocytoma is?

 A

0.3 mg

 B

10 mg

 C

100 mg

 D

200 mg

Q. 20

Dose of clonidine in suppression test done for pheochromocytoma is?

 A

0.3 mg

 B

10 mg

 C

100 mg

 D

200 mg

Ans. A

Explanation:

Answer is A (0.3):

Adult Dose of Clonidine for Clonidine Suppression test is 0.3 mg (0.3mg/70kg) administered orally. Clonidine Suppression Test

  • Clonidine suppression test is useful when plasma catecholamine levels are elevated but not diagnostic. Plasma catecholamines greater than 2000 pg/mL are diagnostic qf pheochromocytoma. if the catecholamine levels are between 1,000 and 2,000 pg/mL clonidine suppression test is performed.
  • The principle behind this test is that in essential (neurogenic) hypertension activation of the sympathetic nervous system results in an increase in plasma catecholamine. However, in patients with a pheochromocytoma, the increased catecholamines are due to the tumor itself, bypassing normal storage and release mechanisms. Therefore Clonidine will not suppress catecholamine release in patients with a pheochromocytoma but will suppress catecholamine release in patients with essential (neurogenically mediated) hypertension
  • Blood is drawn for plasma catecholamines before and 3 hours after the oral administration of clonidine in a dose of 0.3 mg/70 kg body weight.
  • A decrease in plasma norepinephrine by >50 percent is the normal expected response .
  • Consistently elevated levels suggest a diagnosis of pheochromocytoma
  • The test is believed to be 90 percent sensitive.

Q. 21

Pheochromocytoma is usually associated with:

September 2007

 A

Pancreatic exocrine carcinoma

 B

Astrocytoma

 C

Neurofibromatosis

 D

Neuroblastoma

Q. 21

Pheochromocytoma is usually associated with:

September 2007

 A

Pancreatic exocrine carcinoma

 B

Astrocytoma

 C

Neurofibromatosis

 D

Neuroblastoma

Ans. C

Explanation:

Ans. C: Neurofibromatosis

Pheochromocytoma linked to MEN II cart be caused by RET oncogene mutations. Both syndromes are characterized by pheochromocytoma as well as thyroid cancer (thyroid medullary carcinoma). MEN IIA also presents with hyperparathyroidism, while MEN IIB also presents with mucosal neuroma.

Pheochromocytoma is also associated with neurofibromatosis

Quiz In Between


Q. 22

Best for diagnosing pheochromocytoma is:

September 2008

 A

Urinary catecholamines and their metabolites

 B

Serum catecholamines and their metabolites

 C

CT scan

 D

Surgery

Q. 22

Best for diagnosing pheochromocytoma is:

September 2008

 A

Urinary catecholamines and their metabolites

 B

Serum catecholamines and their metabolites

 C

CT scan

 D

Surgery

Ans. A

Explanation:

Ans. A: Urinary catecholamines and their metabolites

The diagnosis of pheochromocytoma is established by the demonstration of elevated 24-hour urinary excretion of free catecholamines (norepinephrine and epinephrine) or catecholamine metabolites (vanillylmandelic acid and total metanephrines).

The measurement of plasma catecholamines can also be of value in the diagnosis of pheochromocytoma.

However, the measurement of plasma catecholamines has limited sensitivity and specificity. Plasma metanephrines have been reported to be more sensitive than plasma catecholamines. Pharmacologic testing with agents such as glucagon or clonidine is rarely required to make the diagnosis



Q. 23

Pheochromocytoma is a feature of all of the following except:     

September 2007

 A

MEN I syndrome

 B

MEN II syndrome

 C

Neurofibromatosis type I

 D

Von Hippel-Lindau syndrome

Q. 23

Pheochromocytoma is a feature of all of the following except:     

September 2007

 A

MEN I syndrome

 B

MEN II syndrome

 C

Neurofibromatosis type I

 D

Von Hippel-Lindau syndrome

Ans. A

Explanation:

Ans. A: MEN I syndrome

Pheochromocytoma are known to occur in certain familial syndromes. These include MEN 2A and 2B, neurofibromatosis (von Recklinghausen disease), and Von Hippel-Lindau syndrome.

The MEN 2A and 2B syndromes, which are autosomal dominantly inherited, have been traced to germline mutations in the ret (rearranged in transfection) proto-oncogene.

The ret proto-oncogene, located on chromosome 10, encodes a tyrosine kinase receptor involved in the regulation of cell growth and differentiation.

Pheochromocytomas occur bilaterally in the MEN syndromes in as many as 70% of cases.

  • MEN 2A (Sipple syndrome) is characterized by medullary thyroid carcinoma, hyperparathyroidism, pheochromocytomas, and Hirschsprung disease. Over 95% of cases of MEN 2A are associated with mutations in the ret proto-oncogene affecting 1 of 5 codons in exon 10.
  • MEN 2B is characterized by medullary thyroid carcinoma, pheochromocytoma, mucosal neurofibromatosis, intestinal ganglioneuromatosis, Hirschsprung disease, and a marfanoid body habitus. A germline missense mutation in the tyrosine kinase domain of the ret proto-oncogene (exon 16, codon 918) has been reported to be present in 95% of patients with MEN 2B.

Q. 24

Pheochromocytoma is characterized by:

September 2007

 A

Headache

 B

Paroxysmal hypertension

 C

Profuse sweating

 D

All of the above

Q. 24

Pheochromocytoma is characterized by:

September 2007

 A

Headache

 B

Paroxysmal hypertension

 C

Profuse sweating

 D

All of the above

Ans. D

Explanation:

Ans. D: All of the above

Symptoms of phaeochromocytoma include the following:

  • Headache
  • Diaphoresis
  • Palpitations
  • Tremor
  • Nausea
  • Weakness
  • Anxiety, sense of doom
  • Epigastric pain
  • Flank pain
  • Constipation
  • Weight loss The classic history of a patient with a pheochromocytoma includes spells characterized by headaches, palpitations, and diaphoresis in association with severe hypertension.

These 4 characteristics together are strongly suggestive of a pheochromocytoma.

In the absence of these 3 symptoms and hypertension, the diagnosis may be excluded.

The spells may vary in occurrence from monthly to several times per day, and the duration may vary from seconds to hours. Typically, they worsen with time, occurring more frequently and becoming more severe as the tumor grows

Quiz In Between


Q. 25

Pheochromocytoma predominantly secretes which hormone:       

September 2007

 A

Serotonin

 B

Epinephrine

 C

Nor-epinephrine

 D

Dopamine

Q. 25

Pheochromocytoma predominantly secretes which hormone:       

September 2007

 A

Serotonin

 B

Epinephrine

 C

Nor-epinephrine

 D

Dopamine

Ans. C

Explanation:

Ans. C: Nor-epinephrine

Relative catecholamine levels also differ in pheochromocytomas.

Most pheochromocytomas secrete norepinephrine predominantly, whereas secretions from the normal adrenal medulla are composed of roughly 85% epinephrine.

Familial pheochromocytomas are an exception because they secrete large amounts of epinephrine. Thus, the clinical manifestations of a familial pheochromocytoma differ from those of a sporadic pheochromocytoma.


Q. 26

Following is true about pheochromocytoma except ‑

 A

Extra – adrenal tumors show zellballen pattern

 B

Follows rule of 10s

 C

90% of non familial cases are bilateral

 D

10 % of pheochromocytomas are extra adrenal

Q. 26

Following is true about pheochromocytoma except ‑

 A

Extra – adrenal tumors show zellballen pattern

 B

Follows rule of 10s

 C

90% of non familial cases are bilateral

 D

10 % of pheochromocytomas are extra adrenal

Ans. C

Explanation:

Ans. is ‘c’ i.e., 90% of non familial cases are bilateral

Pheochromocytoma

  • Pheochromocytoma is a neoplasm of chromaffin cells which usually arise from adrenal medulla.
  • About 10% of these tumors arise at extraadrenal sites, where they are called paraganglioma :­
  • When pheochromacytomas arise at extra-adrenal site, they are referred to as paraganglioma.
  • Paravertebral paragangliomas secrete catecholamines.

Pheochromocvtoma

  • The tumor is composed of polygonal to spindle shaped chromaffin cells or chief cells, clustered with sustentacular cells into small nests or alveoli (zellballen) by a rich vascular network. The nuclei are usually round to ovoid, with a stippled ” salt & pepper” chromatin that is characteristic of most neuroendocrine tumors.
  • Zellballen pattern are seen in paraganglioma.

Pheochromocytomas usually subscribe to a convenient “rule of 10s” :-

  • 10% of pheochromocytomas arise in association with one of several familial syndromes. These include the MEN-2A & MEN-2B syndromes, type I neurofibromatosis, von Hippel-Lindau syndrome & Sturge-Weber syn­drome.
  • 10% of pheochromocytomas are extra-adrenal, occurring in sites such as organ of Zuckerkandl & carotid body, where these chromaffin-negative tumors are usually called paragangliomas to distinguish them from pheochromocytomas.
  • 10% of nonfamilial adrenal pheochromocytomas are bilateral; this figure may rise to 70% in cases that are associated with familial syndromes.
  • 10% of adrenal pheochromocytomas are biologically malignant, although the associated hypertension repre­sents a serious & potentially lethal complication of even “benign”tumors.
  • 10% of adrenal pheochromocytomas arise in childhood, usually the familial subtypes, and with a strong male preponderance. The nonfamilial pheochromocytomas most often occur in adults between 40 & 60 years of age, with a slight female preponderance.

Q. 27

Drug of choice for pheochromocytoma ‑

 A

Propranolol

 B

Phenoxybenzamine

 C

Prazosin

 D

Nitroprosside

Q. 27

Drug of choice for pheochromocytoma ‑

 A

Propranolol

 B

Phenoxybenzamine

 C

Prazosin

 D

Nitroprosside

Ans. B

Explanation:

Ans. is ‘b’ i.e., Phenoxybenzamine 

Pharmacological treatment of pheochromocvtoma

  • Preoperatively or when tumour cannot be removed, blood pressure control is achieved by a-adrenoreceptor blockade which reverses peripheral vasoconstriction →  Phenoxybenzomine is the DOC
  • For hypertensive crises or intraoperative control of BP, phentolamine is the DOC. Prazosin is an alternative. Nitroprusside can also be used-→ Harrison 17th/e p. 1561.
  • In adrenaline secreting tumors, if tachycardia persists, 13-blocker can be added after starting oc-blockers.
  • ACE inhibitor or calcium channel blockers can be used when blood pressure is difficult to control with phenoxybenzamine alone.
  • Metyrosine has been used with some success to block catecholamine synthesis in malignant pheochromocytoma. 
  • Metaiodobenzylguanidine (MIBG) is actively taken up by adrenergic tissue → 123I-MIBG can be used for selective therapeutic irradiation of functioning metastasis.

Quiz In Between



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