Saturday, March 3, 2012
MCQ 4
A 45 year old female develops swelling in her neck and diarrhea. X-ray
shows dense calcification in her thyroid. A nuclear scan of her thyroid
detects a cold nodule that does not concentrate radio-iodine. Her doctor
does serum assays for several hormones. After the hormone is assayed,
he tells her general practitioner that the patient probably has has
medullary carcinoma of the thyroid since one of the hormones is markedly
?What hormone did the doctor most likely assay
a) thyroid stimulating hormone
b) thyroid hormone
c) calcitonin
d) Antidiuretic hormone
e) parathyroid hormone
b) thyroid hormone
c) calcitonin
d) Antidiuretic hormone
e) parathyroid hormone
:Correct Answer
c) calcitonin
:Explanation
Medullary thyroid cancer is a malignancy of the thyroid parafollicular cells. Thyroid parafollicular cells
normally produce the
hormone calcitonin. A malignancy of these cells, therefore, can also
produce calcitonin. Assay of calcitonin is a very good diagnostic test
for medullary carcinoma of the thyroid. Thyroid stimulating hormone
(choice a) is an anterior pituitary hormone and is not produced by the
thyroid gland at all. A tumor of the parafollicular cells would not
produce thyroid stimulating hormone. Thyroid hormone is not produced by
the parafollicular cells, but rather by the follicular cells. A tumor of
the parafollicular cells would not produce thyroid hormone.Antidiuretic
hormone is normally produced by the hypothalamus and released by the
posterior pituitary. ADH can be seen other types
of tumors as ectopic hormone production and produce a paraneoplastic
syndrome. However, a tumor of the parafollicular cells would not produce
antidiuretic hormone To understand which mechanism is responsible for
uptake in medullary thyroid carcinoma one needs to explore the subject
further. This type of carcinoma arises from the neoplastic
transformation of the C-cells of the thyroid. These cells are derived
from the neural crest embryologically rather than the foregut endoderm
as is the remainder of the thyroid. The tumor affects the upper third of
the lateral lobe of the thyroid since this is where most of the C-cells
are concentrated. Medullary carcinoma accounts for 10%% of thyroid
neoplasms. It occurs sporadically in 80-90%% and is familial in 10-20%
of cases. The familial type is transmitted as autosomal dominant and is
associated with the MEN II or MEN III syndrome. Thyroid function tests
are usually normal. Numerous hormones are produced by this neoplasm and
these include calcitonin, ketocalcin, L-Dopa decarboxylase,
carcinoembryonic antigen, serotonin, prostaglandins, ACTH, histaminase
and substance p. It should be noted that the first four hormones are
also secreted by normal C cells. Elevated calcitonin is related to the
secretory diarrhea which occurs in 30% of cases. This particular hormone
is the only sensitive indicator for the presence of tumor because it is
the only one showing response to provocative or suppressive stimuli.
Elevated histaminase correlates well with metastasis.
Saturday, February 25, 2012
MCQ 3
A 16 year old youth is brought to the physician by his mother. She
claims he has been very depressed lately and attributes this to teasing
from school friends because he is so tall.Since he is usually rather
impulsive and tends to have bursts of sudden anger ,she is worried he
may retaliate violently and get 'into a big fight'. During his childhood
he had severe language deficits and very significant academic
difficulties .The mother also stated that a genetic study carried out
during childhood showed the karyotype to be 47xxy. During the course of
examination, he is noted to have a small testes . This boy most likely
has
a) Down's syndrome
b) Klinefelter's syndrome
c) Turner's syndrome
d) Edward's syndrome
e) Marfan's syndrome
Correct Answer:
b) Klinefelter's syndrome
Explanation:
Klinefelter syndrome is the principal cause of male infertility.
It is found to appear about once in every 500 to one in every 1,000 live born males. The 47XXY complement is the most common chromosomal pattern in persons with Klinefelter Syndrome, although mosaic (i.e. 46XY/47XXY) and variant (i.e. 48XXXY) patterns are also observedAbsence of sperm cells (azoospermia) present in almost all patients. only consistent finding seen in all patients is hypogonadism. Testes is small and atrophied to produce sufficient amounts of testosteroneSpeech and language delay is commonly exhibited by XXY males in early childhood Most XXY males are of normal intelligence, although a somewhat decreased global intelligence has been observed as compared to siblings and controls, which appear related to decreased verbal cognitive skills.
Verbal deficits have consistently been observed in childhood and appear to continue into adulthood.Patient’s mental function is normal. There may be impulse control disorder, depression, emotionally disturbed, personality disorder, learning disabilities, and communicatively impaired.
Increase in length between the soles & pubic bone is characteristic. This is due to the epiphyseal openings near the joints remaining open longer than is typical. One major factor in the closing of the epiphyseal plate is when testosterone reaches the desired adult levels. Insufficient testosterone in the body of an XXY therefore often prompts the epiphyseal plate to stay open longer than average and to promote long bone growth in the limbs and extremities.
It is found to appear about once in every 500 to one in every 1,000 live born males. The 47XXY complement is the most common chromosomal pattern in persons with Klinefelter Syndrome, although mosaic (i.e. 46XY/47XXY) and variant (i.e. 48XXXY) patterns are also observedAbsence of sperm cells (azoospermia) present in almost all patients. only consistent finding seen in all patients is hypogonadism. Testes is small and atrophied to produce sufficient amounts of testosteroneSpeech and language delay is commonly exhibited by XXY males in early childhood Most XXY males are of normal intelligence, although a somewhat decreased global intelligence has been observed as compared to siblings and controls, which appear related to decreased verbal cognitive skills.
Verbal deficits have consistently been observed in childhood and appear to continue into adulthood.Patient’s mental function is normal. There may be impulse control disorder, depression, emotionally disturbed, personality disorder, learning disabilities, and communicatively impaired.
Increase in length between the soles & pubic bone is characteristic. This is due to the epiphyseal openings near the joints remaining open longer than is typical. One major factor in the closing of the epiphyseal plate is when testosterone reaches the desired adult levels. Insufficient testosterone in the body of an XXY therefore often prompts the epiphyseal plate to stay open longer than average and to promote long bone growth in the limbs and extremities.
Friday, February 24, 2012
MCQ 2
?What is the diagnosis
- a ) Lichen planus
- b ) Mycosis fungoides
- c ) Ostraceous psoriasis
- d ) Para-neoplastic pemphigoid
- e ) Staphylococcal scalded skin syndrome
- Correct answer : c ) Ostraceous psoriasis
- Explanation:
- These sharply demarcated, erythematous, well-defined limpet-like plaques covered with
- scales and crust are most consistent with ostraceous psoriasis.
MCQ 1
A 45 year old man is referred to a surgeon by his physician because of a swelling in his jaw. The same patient had been regularly visiting his GP with a variety of symptoms,including muscular aches and pains in his arms and legs and abdominal pain. He has a known history of renal calculi. The surgeon suspects the mass in the neck is a Brown's tumour (osteoclastoma).Which of the following biochemical profiles is likely to be elevated?
a) Serum phosphate
b) Serum glucose
c) Serum uric acid
d) Serum amylase
e) Serum calcium
Correct Answer: E
Explanation:
Brown's tumours are found in Primary hyperparathyroidism. Brown tumours (due to
increased osteoclastic activity) are particularly common in the jaw and mandible Primary
hyperparathyroidism is usually detected by an elevated serum calcium during routine
biochemical screening.
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