Acute myocardial infarction is sometimes a diagnostic dilemma in forensic pathology. Our aim is to evaluate the efficacy of
fibronectin by immunohistochemical methods for diagnosis of early myocardial infarction in heart autopsies.Three groups
of cases selected from autopsied hearts submitted to the pathology department of legal medicine organization of Iran
during years 2004-2007 which included 15 cases of definite myocardial infarction (positive control group), 18 cases of noncardiac
death (negative control group) and 26 cases suspicious of myocardial infarction based on clinical presentation just
before death, presence of marked stenosis in at least one major coronary artery and exclusion of other causes of death
(suspicious group). Fibronectin staining was performed on sections prepared from all of the cases.
With our proposed cut off value for fibronectin staining the sensitivity and specificity of this marker are 93.3% and 94.4%,
respectively. This marker could also support the occurrence of myocardial infarction in 42% of our suspicious cases.We
conclude that in spite of usefulness of this marker for detection of myocardial infarction, the results should be interpreted
with caution.
Diagnosis of acute myocardial infarction is a challenging
issue in forensic pathology. In autopsied hearts macroscopic
findings of myocardial infarction accompanied by microscopic
confirmation are the gold standards for diagnosis. However,
the development of these changes requires time and in real
practice we rarely are fortunate enough to see the typical
cases. In most instances nothing other than significant
narrowing of coronary arteries is found in favor of myocardial
infarction. Use of an ancillary method is highly advocated in
these situations. Application of triphenyltetrazolium chloride
to the fresh myocardium, electron microscopy and some
immunohistochemical markers including myoglobin, fatty
acid binding protein (FABP), troponin, desmin, fibronectin,
fibrinogen, C5b-9 and vascular endothelial growth factor
(VEGF) are among many different diagnostic methods
which have been used to address this diagnostic dilemma. The electron microscopy is not available in every
pathology laboratory and requires comprehensive expertise.
The triphenyltetrazolium chloride method requires fresh
tissue and a great deal of suspicion at the time of autopsy.
The immunohistochemical studies are, however, promising
alternatives. The aim of the current study is to evaluate the
diagnostic power of one of these immunohistochemical
markers, the fibronectin, in suspicious cases of myocardial
infarction.
The autopsied hearts were fixed in 10% formalin and tissue
sections processed routinely. The processed sections were
embedded in paraffin block and from which 4 micrometerthick
slide sections were prepared and transferred to sialinized
microscopic slides. The slide sections incubated for one hour
in 60˚C and then deparaffinized in two changes of xylene
each for 5 minutes. Then the endogenous peroxidase activity
was blocked by incubation for 15 minutes using 3% hydrogen
peroxide in methanol. After washing with Tris-buffered
saline (TBS), the slides were incubated for 35 minutes by the
primary antibody (1/1000 dilution of a proprietary Rabbit anti
human fibronectin, monoclonal antibody, Dakocytomation,
Denmark). Next the unbound antibody was washed away
by floating the slides in three changes of TBS, three minutes
each. Finally, the potentially bounded antibodies were
developed and detected by LSAB2 System-HRP detection kit
(Dakocytomation, Denmark) according to the manufacturer’s
instructions.
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