Application of immunohistochemistry in clinical practice: a review

BACKGROUND

Immunohistochemistry (IHC) has radically altered the practice of diagnostic histopathology. It is increasingly being applied for more accurate and precise diagnosis, theranostics and prognostics in the management of tumours. Unfortunately clinicians and pathologists in resource-constrained settings may not be exposed to its clinical utility.

OBJECTIVES

To provide a review of the principles and utility of IHC in diagnosis as relevant to histopathological diagnosis in clinical practice.

DATA SOURCES

A retrospective PubMed search was used to find most recent studies and reviews published on immunohistochemistry. Popular anatomical pathology textbooks and online resources were also searched.

STUDY SELECTION

The searches for articles were limited to the MeSH terms "humans" and "English language". Emphasis was placed on recent review and original articles that are dealing directly with respective technical aspects and immunohistochemical stains of interest.

DATA EXTRACTION

Both authors searched and reviewed related articles separately.

DATA SYNTHESIS

The extracted information was compared so as to include the most updated information available.

CONCLUSIONS

Immunihistochemistry has become an essential component of histopathology. Clinicians need to be conversant with developments in IHC in order to liaise appropriately with pathologists for the benefit of their patients. There is a need for urgent establishment of IHC practice within resource-constrained countries in order to meet current diagnostic standards in tumour pathology.

Fatal firearm wounds: a clinicopathologic study

Firearm-related injuries are a leading cause of morbidity and mortality in South Africa. This retrospective autopsy study included all firearm-related fatalities seen at a central mortuary in Durban. These cases had initially been assessed by a clinician before death, from July 1998 to June 1999.A total of 322 cases of fatal gunshot wounds were reviewed. Medical records and postmortem findings were compared by data capture onto a spreadsheet. Twenty-eight cases were excluded because of surgical alteration of the wounds, making autopsy evaluation impossible. In 50.7% of cases, the number of wounds was correctly identified and in 55.1% the position was correctly identified. In only 36.1% of cases were the entry and exit wounds correctly identified. The total number of missed wounds was 504 (48.3% of cases). The majority of missed wounds were on the upper limbs (25%), with the anterior trunk (21.8%) and lower limbs (18.5%) making up the remainder. This study demonstrates that physicians in South Africa do not adequately document and interpret gunshot wounds, which may influence the treatment of the patient and have medicolegal consequences. Emphasis should be placed on undergraduate and postgraduate teaching for physicians to correctly identify, interpret, and document firearm wounds.

Lymphoproliferative disorders in Oxford renal transplant recipients

BACKGROUND

Increased cancer incidence, particularly lymphoproliferative disease, is a complication of immunosuppression in organ transplantation. Non-Hodgkin's lymphomas (NHLs) occur frequently during the first year after transplantation, more so in North America than in Europe.

METHODS

This study audited and correlated the demographic, clinical, pathological, and outcome features of post-transplant lymphoproliferative disorders (PTLDs) in a large centre in Oxford, and assessed whether the time of onset fitted more with the European or North American pattern.

RESULTS

There were 1383 renal transplants in the study period and 27 patients developed lymphoma: 26 NHLs and one Hodgkin's disease (1.95%). Four of the patients never received cyclosporin. The mean time of diagnosis after transplant was 46 months. Most tumours (21/27) presented extranodally. Management included reduction of immunosuppression, surgical excision, antiviral treatment, radiotherapy, and chemotherapy. Three patients presented in the first post-transplant year-0.34% of cyclosporin managed patients-similar to the North American incidence, although the incidence of extranodal late PTLDs was also high (mean onset, 36 months v 15 months international mean). Post-transplant lymphomas were the most common malignancy associated with death in transplant patients.

CONCLUSIONS

PTLDs occurred in 2% of renal transplant patients, presenting both in the first year in association with cyclosporin use, as in North America, but also in subsequent years, giving an overall presentation time later than the international mean. The disease usually presented extranodally, accounting for the wide range of symptoms and signs. Despite awareness and active management, the disease contributed to death in more that 50% of patients with PTLDs.

Sudden death caused by myocardial tuberculosis: case report and review of the literature

A 25-year-old fit man died suddenly while playing social soccer. Autopsy revealed an infiltrative lesion involving the left ventricle with overlying pericarditis. No other significant pathologic changes were observed. Histologic examination showed necrotizing granulomatous inflammation. No acid-fast bacilli were demonstrated in the pericardial fluid or on histologic examination. The presence of Mycobacterium tuberculosis DNA complex was confirmed by use of the ligase chain reaction technique. The differential diagnosis of myocardial tuberculosis includes sarcoidosis, rheumatic fever, rheumatoid arthritis, giant-cell-containing tumors, idiopathic (giant-cell) myocarditis, and bacterial infections such as tularemia and brucellosis. This case illustrates the protean manifestations of tuberculosis and highlights the use of molecular biologic techniques in arriving at a definitive diagnosis in cases of suspected tuberculosis.

Mechanical airway obstruction caused by accidental aspiration of part of a ballpoint pen

The authors present three cases of death in children aged 4, 9, and 10 years, respectively, that were first thought to be caused by herbal or other poisonings but at autopsy were found to be caused by airway obstruction from aspiration of ballpoint pen parts. Aspiration of a foreign body is a leading cause of accidental death in children, but the circumstances in these cases were unique. In the first case, a 4-year-old child died shortly after a visit to a traditional healer. The child's mother blamed him for the death and fatally assaulted him. The second case was a 9-year-old who died at school. Case 3 was a 10-year-old who collapsed while playing with a ballpoint pen in her mouth. In the latter two cases, the relatives alleged poisoning. At autopsy, there was no evidence of trauma, disease, or poisoning in all three cases. Ballpoint pen parts were present in the larynx, carina, and left main bronchus, respectively. Features of "asphyxial" death were present, and included subconjunctival hemorrhages, subendocardial hemorrhages, and congestion of the face and internal organs. These deaths are preventable by education of children, parents, and teachers. Ballpoint pen manufacturers should also modify the design of these pens to improve their safety.

Courting disaster? A survey of the autopsy service provided by district surgeons in Kwazulu-Natal

AIM

To provide information on the overall quality of the autopsy service provided by district surgeons in KwaZulu-Natal (KZN) and in particular to identify factors which may have a negative impact on the judicial process.

METHOD

Confidential questionnaires were sent to 73 district surgeons and 216 legal practitioners including prosecution advocates, regional court prosecutors, defence advocates and attorneys. One hundred and twenty (43%) replies (47 doctors and 73 lawyers) were suitable for analysis.

RESULTS

District surgeons have no shortage of experience or maturity but their performance is hampered by the following: lack of appropriate training in forensic pathology; high case load; inadequate facilities and support staff; and lack of access to ancillary services.

CONCLUSION

This study has shown that the standard of autopsy services by district surgeons varies considerably. Overall, there is evidence that inadequacies on the part of district surgeons have negative repercussions for the criminal justice system. Urgent attention should be given to implement training programmes for the district surgeons and to improve service conditions.

Membranous fat necrosis due to subcutaneous elemental mercury injections

Membranous fat necrosis (MFN) is a distinct abnormality in systemic and subcutaneous fatty tissue. Although ischemia and trauma have been implicated in its causation, the exact pathogenesis of MFN remains unknown. The deposition of metallic mercury in subcutaneous tissue due to accidental penetration or deliberate injection of mercury is unusual. Depending on the duration of the deposition, localized necrosis, suppuration, and granuloma formation have been described at mercury injection sites. We report subcutaneous MFN, a hitherto unrecognized histopathologic phenomenon at sites of mercury deposition, in a 21-year-old soccer player who had deliberate subcutaneous and intramuscular elemental mercury injections to improve his sporting performance.

Histological evidence of hypertrophy and ischaemia in sigmoid volvulus among Africans

OBJECTIVE

To document histological evidence of hypertrophy and ischaemia in sigmoid volvulus among Africans.

DESIGN

Retrospective case series study of the histology of sigmoid volvulus over seven years with cadaveric controls.

SETTING

King Edward VIII Teaching Hospital, University of Natal, Durban, South Africa.

SUBJECTS

Fifty African patients with sigmoid volvulus and nine cadavers with normal sigmoid colon.

RESULTS

There was hypertrophy of the submucosa, muscularis propria and nerve plexuses with features of ischaemia in the patients' specimens. Their veins were thrombosed and recanalized while mesentery and submucosa had fibrosis and vascular hyalinization. There was also hypertrophy and hyperplasia of Meissner's nerve plexus. In the autopsy study, normal African sigmoid specimen showed similar ischaemic features but specimens from the four Indian patients in the study did not have such abnormalities.

CONCLUSION

We postulate that chronic ischaemia may account for postoperative anastomosis dehiscence in some cases where the resection margins involved the hypertrophic segment. The benefit of an extended resection with anastomosis being effected on the bowel with apparent normal thickness to avoid this possibility should be investigated.

Focal nodular hyperplasia of the liver coexisting with an adrenal pseudocyst

A case of focal nodular hyperplasia (FNH) of the liver and an adrenal pseudocyst coexisting in the same patient is presented. The presentation was due to the large adrenal pseudocyst, which caused abdominal pain and swelling. At operation, the FNH was noted as an incidental finding. The aetiopathogenesis of both these lesions is thought to be the result of vascular malformation. FNH is associated with several other vascular malformations and lesions, and the association with an adrenal pseudocyst extends this concept. It also lends support to the theory that vascular abnormalities are important in the causation of these lesions.

TAL-1 protein expression in vascular lesions

The distribution of TAL-1 protein, an important vascular promoter in mice, has been examined immunohistochemically in a range of human vascular lesions and normal tissues. Formalin-fixed, paraffin-embedded vascular lesions including granulation tissue, haemangiomas, Kaposi's sarcomas, spindle cell haemangioendotheliomas, and angiosarcomas, were examined using a monoclonal antibody to recombinant TAL-1. Endothelial cells in all lesions gave positive immunostaining of variable intensity. Granulation tissue and spindle cell areas of the vascular tumours gave the strongest staining (nuclear and cytoplasmic). The better-differentiated endothelial cells within the tumours and resident well-formed vessels were less positive and some cells were in fact negative. The malignant endothelial cells in angiosarcomas showed less intense positive staining than KS cells. This study has shown TAL-1 protein expression in a range of reactive, benign, and malignant vascular lesions. Protein expression appears to be stronger in the spindle cell areas, perhaps reflecting greater expression in less-differentiated endothelial cells.

The immunoexpression of bcl-2 and p53 in Kaposi's sarcoma

The aim of this study was to examine the immunohistochemical expression of p53 and bcl-2 in Kaposi's sarcoma and relate this with proliferation index (as measured by MIB-1 staining) and clinicopathological subtypes. Twenty formalin-fixed, paraffin-embedded cases of Kaposi's sarcoma were stained with commercially available antibodies to p53, bcl-2 and MIB-1, after pressure cooking antigen retrieval. All cases were strongly positive for bcl-2 with the majority containing more than 75% positive cells. In comparison, p53 expression was less striking. Eleven cases contained less than 24% (+1) of cells staining positively. Only two cases showed greater than 75% of positive cells, and both of these latter two lesions had metastasized. The MIB-1 staining in all cases of Kaposi's sarcoma was strongly positive, irrespective of clinicopathological type, in keeping with the highly proliferative nature of this lesion. Thus, we have demonstrated uniformly increased expression of bcl-2 protein in Kaposi's sarcoma irrespective of clinicopathological subtype and MIB-1 staining, while p53 expression is relatively less common, except in those cases which have metastasized. This may help identify those cases that will behave in a more aggressive manner. However, more cases need to be evaluated to verify this.

Thymidine phosphorylase expression in Kaposi sarcoma

AIMS

To examine the immunohistochemical distribution of thymidine phosphorylase (TP) in all clinicopathological subtypes of Kaposi sarcoma.

METHODS

Thirty two biopsy specimens of Kaposi sarcoma (29 patients) were studied. Six of these patients represented classic, six endemic, eight HIV associated, seven post-immunosuppression/transplant related, and two unclassified variants of Kaposi sarcoma. The average age was 49 years (range 22-83 years) and the male: female ratio 24:5. Four samples of angiosarcoma and one of spindle cell haemangio-endothelioma were stained in parallel. All specimens were fixed in formalin, embedded in paraffin wax and processed routinely. Immunohistochemistry was carried out using an antibody directed against CD31 (JC70) and the monoclonal antibody P-GF.44C against TP.

RESULTS

All biopsy specimens showed immunoexpression for TP. The spindle cell component stained more strongly than newly formed endothelium lined vessels and normal, resident vessels at a distance from the lesions.

CONCLUSIONS

The strong immunoexpression of TP suggests up-regulation of TP and a role for TP in angiogensis in Kaposi sarcoma. The mechanism for the up-regulation of TP remains unknown, but viral infections may trigger it. The differential staining of the various cell components of Kaposi sarcoma also suggest that TP either plays a role in the differentiation and maturation of Kaposi sarcoma or is a reflection of such changes.

Cerebral infarction and intracranial arterial dissection in closed head injury

This report describes the autopsy findings in three cases of closed head injury dying of cerebral infarction, with brain swelling and herniation. In each instance the cause of the infarct was found to be subintimal dissection involving intracranial anterior circulation arteries. The autopsy findings underscore the value of histological examination of vessels that macroscopically appear thrombosed. We discuss factors that impact on the reported incidence and make brief mention of problems surrounding the true pathogenesis of this lesion.

Sudden death caused by testicular germ cell tumour

Most cases of sudden unexpected 'natural' death are due to primary disorders of the cardiovascular, respiratory and central nervous system. Sudden death due to a previously undiagnosed malignancy is rare in young, apparently healthy subjects. We report an unusual cause of sudden unexpected death due to pulmonary tumour embolism complicating an undiagnosed germ cell tumour of the testis in a 37-year-old white male. Although death due to testicular tumours is not uncommon in young adult males, it rarely follows pulmonary embolism secondary to inferior vena cava (IVC) tumour invasion. A review of the literature revealed four other cases with a similar mechanism of death.

Laryngeal cyst and sudden death

Laryngeal cysts are relatively uncommon and account for about five per cent of benign laryngeal lesions. The commonest location is the epiglottis. Pathologically these lesions may be divided into epithelial, tonsillar or oncocytic types. The patients may be asymptomatic or present with hoarseness, dysphagia, cough or airway obstruction. Epithelial cysts of the larynx, although histologically benign, may produce sudden and unexpected death from asphyxia. A case is presented of a 32-year-old female who was sexually assaulted and later found dead. Death was most likely due to laryngeal obstruction caused by an epiglottic cyst. Alcohol intoxication (BAC = 0.25g%) is likely to have been a contributory factor. In this case the results of the autopsy helped to exonerate the accused from being charged with murder. Other medico-legal problems that may be encountered with laryngeal cysts are difficulty in intubation and accidental rupture of a cyst during intubation or otolaryngeal examination.

Medicolegal aspects of cerebral amyloid angiopathy. A case report

Autopsy examination performed on a 75-year-old woman who had been in a minor road traffic accident revealed an occipital lobar hematoma with subdural extension. Histological examination of brain tissue showed the presence of severe cerebral amyloid angiopathy. Diagnostic techniques and correlation and interpretation of these findings are discussed.

Shotgun pellet embolism to the brain

This report describes the autopsy findings in a young man who died after having been shot with a shotgun from about 30 m. Although not suspected clinically, a right middle cerebral artery territory infarct was found; its cause was shown to be a shotgun pellet embolus that had lodged just proximal to the trifurcation of the right middle cerebral artery. The case underscores the importance of performing a thorough postmortem examination, including a careful study of cerebral vasculature, in instances of brain infarction.

A retrospective analysis of alcohol in medicolegal postmortems over a period of five years

Violence and violent death are everyday events in present-day South Africa. Although this phenomenon may be attributed in great part to the sociopolitical environment, the single most important underlying common factor is the presence of alcohol in both the perpetrators of violence and their victims. We retrospectively studied 948 cases of 2,980 medicolegal autopsies done over a 5-year period. We found that 52.5% of cases tested positively for alcohol, with blood alcohol concentration varying from 0.008 to 0.048 g% (mean = 0.18). Male patients were more common and more likely to be positive than female patients. Breakdown of the cases into various modes of death showed that homicides, vehicular accidents, and suicides predominated. The results are in agreement with earlier studies done locally and elsewhere.

The emergence of penicillinase-producing strains of Neisseria gonorrhoeae in Durban

Gonorrhoea was diagnosed in 179 (87%) of 206 Black males who presented with urethritis at a sexually transmitted disease clinic at the King Edward VIII Hospital, Durban. Penicillinase-producing strains of Neisseria gonorrhoeae were detected in 7 (5%) of 140 gonococcal isolates, and a further 13 strains were relatively resistant to penicillin. Microscopic examination of Gram-stained smears provided a rapid presumptive diagnosis of gonorrhoea in 162 cases. The modified Thayer-Martin medium proved marginally superior to chocolate agar for the isolation of N. gonorrhoeae from urethral exudates. The causation and laboratory diagnosis of urethritis in males and the antibiotic susceptibility pattern of the gonococcal isolates are discussed.