Pathology

January

2006

Vol. 1 No. 1

New PathCare Pathologists

Prediction of the GlomerularFiltration Rate(GFR)

The National Health Act and its Impact on Medical Practitioners

Fixation the Diagnosis starts here!

Ameloblastoma

3 5 74

FeaturesThe National Health Act and itsImpact on Medical Practitioners

Prediction of the GlomerularFiltration Rate (GRF)

New PathCare Pathologists

Fixation - the Diagnosis starts here!

Ameloblastoma

ss

a)

t

e

m

2

3

4

5

7

Editorial TeamEditor

Dr Dawie de Beer

ProductionDr Ross MillinElandi Bishop

Design and LayoutAd le Borton, Brent Davids

Hannes Vosloo, Mark Calvert

e-mailnews@pathcare.co.za

ManagementCEO

Dr Bruce Dietrich

Director Pathology Operations Dr John Douglass

Director Operations AfricaDr Nasser Mia

Director Special OperationsDr Johan van Wyk

Chief Systems OfficerDr Clive Prior

Chief Financial OfficerMs Julie Buissinne

Human Resources DirectorVacant

A list of PathCare Pathologists is available on our website at www.pathcare.co.za

Pathologist contact email clients@pathcare.co.za

é

PathCare Business Centre • PathCare ParkDrs Dietrich, Voigt, Mia & Partners

Neels Bothma Street • N1 City • Goodwood • 7460 Private Bag X107 • N1 City • Goodwood • 7463

Tel : (021) 596 3400 • Fax : (021) 596 3726

Published January 2006 by:

Drs Dietrich, Voigt, MiaVennote Partners

S A N A S

ACCREDITEDLABORATORY

ISO / IEC17025 / 15189

pathology forum

From the EditorThe year 2005 was a particularly active year at PathCare. Early in the year we moved to our new Reference Laboratory and Business Centre at N1City. We grew locally and focussed on international expansion. The year also witnessed the introduction of ICD10 coding in South Africa which required much attention. A number of pathologists in the practice reached retirement age and were replaced by pathologists of a new generation – see page 4.

Inspired by the changes in the PathCare environment the editorial team decided that the Pathology Newsletter which was first published in 2000, needed to be revamped. The appearance and lay-out were completely changed and the magazine was renamed the PathCare Pathology Forum. We herewith proudly present the first edition of the Forum.

The contributors to this edition are Prof Mo Dada, a histo- and forensic pathologist and chairman of the PathCare Group until the end of 2005, Dr Esmé Hitchcock, a chemical pathologist at the Reference Laboratory and at our Durbanville and Paarl laboratories, Dr Rudi Botha, a histopathologist at Panorama Medical Centre and Prof Vince Phillips, professor and forensic dentist in the Department of Oral Pathology at UWC and part-time oral pathologist at PathCare. We thank them for their contributions.

x

2

Introduction

Rights and duties of users and health care providers

The National Health Act (Act 61 of 2003) was assented to on 23 July 2004. It is to be progressively brought into effect once the necessary regulations have been promulgated. It will have a major impact on health services in the country and will also affect the practice of medicine. Therefore, all medical practitioners should have a basic knowledge of the Act. This article does not discuss aspects of the Act that have not yet come into effect such as the use of human tissue (Chapter 8) and the certificate of need (Chapter 6). Both issues will be fleshed out in regulations that are to be published for comment in the near future.

The Act refers to “health care personnel” that includes both health care providers and health workers. A “health care provider” is defined as a person providing health services in terms of any law (e.g. nurse, doctor, physiotherapist, etc.) A “health worker” is a person who provides health services to a user, but does not include a health care provider (e.g. hospital porter, receptionist, etc.)

Patients are referred to as “users”. A “user” is a person receiving treatment in a health establishment, including receiving blood or blood products, or using a health service. If the “user” receiving treatment or using a health service is below the age of consent for medical treatment (14 years) and operations (18 years), the term “user” includes the person’s parents or guardian or another person authorised by law to act on their behalf (e.g. a curator).

The rights of users of health services and the reciprocal duties imposed on health care providers are set out in the Act. They include the right to emergency treatment, to participate in decision making, informed consent, consent in respect of incompetent persons and in emergency situations, confidentiality, protection of health records and access to information, and the right to complain.

The Act specifically mentions the right not to be refused emergency medical treatment (S 5). This means that a doctor has to treat and stabilize a seriously injured patient before transferring such a patient even if he or she cannot afford to pay for medical care. The Act also provides that a user has the right to participate in any decision affecting his or her personal health and treatment (S 8). This means for example, that if a child is old enough to understand the nature and effect of the treatment he or she should be consulted and informed of the procedure even though he or she may not be legally competent to give consent. In such a case consent must be given by the legally competent person authorised to do so on his or her behalf. The Act specifies a hierarchy of persons who may give such consent. Apart from persons authorised by the court, the order of priority is consent by spouse or partner, parent or guardian, grandparent, or adult brother or sister.

Legally competent patients also have the right to refuse health services and they should not be treated without consent unless any delay in the provision of the health service might result in their death or irreversible damage to their health and they have not expressly, impliedly or by conduct refused that service.

The usual rules regarding confidentiality embodied in the Constitution and the Promotion of Access to information Act (Act 2 of 2000) have been incorporated into the Act. Thus disclosure of health records may only be made with the written

Prof Mo Dada

the national health act and its impact on medical practitioners

pathology forum

the national health act and its impact on medical practitioners

consent of the patient unless a court order has been obtained or where non-disclosure of the information would represent a serious threat to public health. Furthermore, patients have the right not to have their medical records examined fo r t rea tment , s tudy, teach ing or research purposes without their consent.

Finally, patients have a right to lay a complaint about the manner in which they were treated at a health establishment and have the complaint investigated.

Which equation to use?

Limitations

Interpretation

Implementation

In adults, the MDRD, Abbreviated MDRD and Cockroft-Gault equations are all endorsed by the National Kidney Foundation.

The Cockroft-Gault formula was developed to predict creatinine clearance. It was derived from 24hr urine creatinine clearance as gold standard. Of the subjects, 96% were male and no information on race was given. It is reported that the Cockroft-Gault equation tends to overestimate the GFR and results appear more widely dispersed than with the MDRD equation.

The MDRD was developed from the Modification of Diet in Renal Disease Study data. Radioactive marker clearance was used as the gold standard. GFR is

2expressed per 1.73m of body surface area. Of the subjects, 60% were male and 12% were black. Evaluation studies report that this equation seems to

underestimate the GFR, but better precision is obtained compared to Cockroft-Gault.

An abbreviated MDRD equation was also published, using only serum creatinine, for cases where albumin and urea are not available. Results correlate well with the original MDRD calculation.

The equations above are only applicable to adults. In children, the Schwartz formula should be used, based on serum creatinine and height.

The GFR prediction equations assume that the patient is in a steady state and that the average rate of creatinine production can be estimated. Therefore, the equations will be unreliable if the level of GFR is rapidly changing, if muscle mass is unusually high or low or if dietary creatinine intake is unusually high or low. A creatinine clearance is therefore necessary to estimate GFR in the following conditions: pregnancy, obesity, malnutrition, paraplegia, muscle wasting, amputation, vegetarian diet, creatine supplements.Prediction equations also do not perform well in people with normal or mildly impaired renal function.Creatinine clearance would probably provide a more accurate estimate of GFR in these cases too.

In patients with chronic kidney disease, the stage of disease can be assigned based on the level of kidney function, as estimated by the MDRD equation:

The National Kidney Foundation strongly recommends the use of GFR prediction equations to improve the GFR estimating ability of serum creatinine results. These calculations have now been implemented in our laboratory. As the MDRD requires albumin and urea, and the Cockroft-Gault requires weight, these calculations need to be requested specifically. The abbreviated MDRD will be reported with routine creatinine results, if the age and sex of the patient are available.

The GFR is considered the best overall index of renal function. Urinary clearance of inulin or radioactive markers provide an accurate measurement of GFR, but t h e s e m e t h o d s a r e cumbersome and not readily available. Instead, the creatinine clearance is g e n e r a l l y u s e d f o r determining GFR. As it involves a 24hr urine collection, it is unfortunately time-consuming and prone to errors.

Many clinicians rely on the serum creatinine concentration as an indicator of GFR. The accuracy of this estimate is however limited, because the serum creatinine concentration is affected by factors other than GFR, e.g. muscle mass, dietary intake, drugs, ketosis, extra-renal excretion and renal tubular secretion. Serum creatinine is also an insensitive index of decreased GFR - the serum creatinine level generally does not rise above the laboratory reference range before the GFR is reduced by 50%. Many individuals with decreased GFR may therefore have a serum creatinine level within the normal range.

Several formulas have been developed which incorporate age, sex and body size together with the serum creatinine concentration, yielding a GFR estimate which is considerably more accurate and precise than when using serum creatinine alone.

Cockroft-Gault

MDRD

Abreviated MDRD

Schwartz

S-creat, age, sex, weight

S-creat, s-urea, s-alb, age, sex, race

S-creat, age, sex, race

S-creat, height, age, sex

Information requiredFormula

ReferencesAnn Intern Med. 1999;130:877-84NKF K/DOQI Guidelines 2002Pediatrics 2003;111:1416-21J Am Soc Nephrol. 2003;14:2573-80

Dr Esmé Hitchcock

STAGES OF CHRONIC KIDNEY DISEASE

Stage

1

2

3

4

5

Description

Normal

Mild in GFR

Moderate in GFR

Severe in GFR

Kidney failure

GFR (ml/min/1.73m²)

>90

60 - 89

30 - 59

15 - 29

< 15

3

pathology forum

prediction of the glomerular filtration rate (GFR)

4

pathology forum

new pathcare pathologists

DR BRUCE MATELAKENGISA

DR TERESA NEL

DR RYAN SOLDIN

DR RUSTUM SOLOMON

MBChB FCPath (SA) (Anat)HistopathologistClaremont

MBChB MMed (Haem) MBAHaematopathologistBoemfontein

MBChB MMed Path (Anat)HistopathologistGeorge

MBChB FCPath (SA) (Anat)HistopathologistPanorama

A number of young pathologists joined the PathCare Group during 2005 to replace colleagues who have retired or resigned. They are:

DR NTSIKI BAARTMAN

DR CHRIS EEDES

DR ALICIA ELS

DR DAVID MARX

DR WESSEL MEYER

BSc (Hons) (Chem) MBChB FCPath (SA) (Haem)HaematopathologistPathCare Reference LaboratoryN1 City

MBChB DTM&H DA(SA) MMed Path(Anat) DIP FOR MED(SA) HistopathologistRondebosch

MBChB MMed (Haem Path)HaematopathologistPathCare Reference LaboratoryN1 City

BSc MBChB FCPath (SA) (Anat)HistopathologistPort Elizabeth

MBChB FCPath (SA) (Chem)Chemical PathologistBloemfontein

VEREENIGING

Kroonstad SasolburgKuruman

Mafikeng

GEORGE

Bethlehem

Welkom

Knysna

Oudtshoorn

Queenstown

King Williams Town

PortAlfred

Vryburg

Aliwal North

JeffreysBay

WORCESTERPAARL

Mossel Bay

EAST LONDON

PORT ELIZABETH

MeyertonPotchefstroom

KLERKSDORP

VredendalVredenburg

CAPE TOWN

BELLVILLE

KIMBERLEY

BLOEMFONTEIN

SOMERSETWEST

MaseruLesotho

Plettenberg Bay

Milnerton

Durbanville

Swakopmund

Walvis Bay

Upington

Luderitz

WINDHOEK

Otjiwarongo

OndangwaOshakati

Namibia

Republic ofSouth Africa

Springbok

Alexander Bay

Drs Dietrich, Voigt, MiaVennote Partners Visit our website www.pathcare.co.za for further information

Laboratories

VEREENIGING

Sasolburg

Heidelberg

Bethlehem

EAST LONDON

Meyerton

Harrismith

SOMERSET WESTTel : (021) 852 3144Fax : (021) 851 6240

Practice No. 5200539

Drs Izak Loftus, Linda Steyn

EAST LONDONTel : (043) 701 5900Fax : (043) 701 5950

Practice No. 5200539

Dr R.P. Mulligan

GEORGETel : (044) 803 8200

Practice No. 5200539

Drs Laing, Soldin & Venter

VEREENIGINGTel : (016) 440 6300 / 79

Fax : (016) 455 5749

Practice No. 052 000 001 9356

Drs Soldin Le Roux

Practice No. 052 000 001 9356

Drs de Beer, van Zijl,Mattana & Louw

KLERKSDORPTel : (018) 468 9000Fax : (018) 468 9010

BETHLEHEMTel : (058) 303 4961Fax : (058) 303 7687

Practice No. 052 000 001 9356

Dr M CrausePractice No. 052 000 001 9356

Dr M Crause

WELKOMTel : (057) 391 0400Fax : (057) 352 5916

BLOEMFONTEINTel : (051) 401 4600

Practice No. 052 000 001 9356

Drs Voigt &Vennote Partners

Practice No. 052 000 001 9356

Drs Voigt &Vennote Partners

PORT ELIZABETHTel : (041) 391 5700Fax : (041) 391 5702

Practice No. 5200539

Drs Hofmeyr, KasongoVennote Partners

KIMBERLEYTel : (053) 830 8960Fax : (053) 831 2398

Practice No. 5200539

Dr Dotti von Ulmenstein

CAPE TOWNPathCare Reference Laboratory

PathCare Park, N1 CityTel : (021) 596 3400

Fax : (021) 596 3727

WORCESTERTel : (023) 347 1021Fax : (023) 342 8723

Practice No. 5200539

Drs Dietrich, Voigt, Mia Vennote Partners

PAARLTel : (021) 872 5158Fax : (021) 872 5393

Practice No. 5200539

Dr Illse Louw

Practice No. 052 000 000 6238Drs Burger, Venter, Van Greunen & Partners

WINDHOEKTel : 09264 (61) 283 6000Fax : 09264 (61) 283 6020

almost identical results. Bouin's, Zenker's and B-5 are excellent fixatives for routine work and most immunohistochemical stains but preservation of nucleic acids is poor.

Carnoy's fixative is a mixture of ethanol, chloroform and glacial acetic acid. It dissolves most of the fat while fixing the tissues, a property that has been found useful in identification of lymph nodes in radical resection specimens.

While there is a constant search for the universal all-purpose fixative dictated by the desire to perform the most topical and current new techniques in histopathology as diagnostic aids, the most sensible approach is to handle the tissue according to the recommendations for the particular technique being employed. This implies that there is both enough tissue to work with and that the method of fixation should be considered while the tissue is still fresh. One may console oneself however with the fact that formalin will allow for most of the techniques to be carried out, although imperfectly. DNA preservation, for example, is best obtained with buffered, and not acid, formalin at 4 °C rather than at room temperature.

The best approach in fixing cytology specimens is to consider the specific specimen type that is submitted.

Fix IMMEDIATELY with spray fixative (Cytofix®), holding container approximately 30 cm from the slide. Any delay in placing specimens onto slides, or delay in fixation, can result in the specimen rapidly drying out and so being unsuitable for accurate cytological examination.

Voided urine, catheter urine and renal pelvic and bladder washings are specimens submitted for cytological assessment. Ten to 30 ml of urine is usually adequate and large volumes are not required. Specimens should be processed immediately or refrigerated and processed as soon as possible. If a delay is anticipated, immediate fixation with equal volume of 50% alcohol (ethanol) may preserve the specimen for several days.

It is mandatory to get a good representative sample of the lower respiratory tract, this is evidenced by the presence of carbon-laden macrophages or bronchial mucosal cells in the sputum. Many sputum specimens are poorly collected samples and contain mainly saliva. A minimum of 1 ml of sputum is preferred. Sputum is NOT TO BE PRESERVED IN ALCOHOL as this causes severe mucolytic changes. If processing is to be delayed, refrigerate the specimen. Sputum samples should be stored in the fridge until transported to the laboratory for analysis. This helps prevent cell degeneration and overgrowth by organisms.

The specimen is collected by the doctor in a clean `specimen trap'. An equal volume of 50% alcohol for preservation may be added and the specimen may be stored in the fridge prior to processing.

Insert the brush into a specimen container with 50% alcohol or roll the contents of the brush onto a clean, labelled glass slide and fix immediately with spray fix.

Equal volume of 50% alcohol for preservation and the specimen may be stored in the fridge prior to processing. For differential count add equal volume of formalin and deliver immediately, on ice, to cytology laboratory.

When body fluids are tapped, they should always be submitted for cytologic examination. Large effusions, when initially tapped, may not be adequate due to degenerative changes or poor cellular yield.

Fixation of cytology specimens

Gynaecological smear preparations:

Urine:

Sputum:

Bronchial washings:

Bronchial brush preparations:

Brocho-alveolar lavage:

Pleural, pericardial and peritoneal fluid:

Timeous, effective and correct fixation of histology and cytology specimens is cardinal in preservation of cellular detail and thus for accurate interpretation of pathological processes.

10% buffered formalin is still the gold standard in tissue fixation as it is cheap, tissue does not deteriorate with prolonged exposure

and it is compatible with most special stains and immunohistochemical techniques. Optimally, specimens should be placed in formalin within 30 minutes of surgical removal and processed within 24 to 48 hours to avoid 'overfixation'. Contrary to popular belief, tissue shrinkage is minimal in formalin. Shrinkage is a manifestation of the inherent contractile qualities of the specimen itself and occurs independent of fixation. To avoid considerable diminution, a specimen should be pinned on a rigid base like a corkboard. Formalin penetrates tissue at about 1mm/hour but tissue penetration does not equate to fixation. Formalin penetrates 'fast' but fixes 'slowly' necessitating fixation times of several hours for most specimens. Fixation times are shortened in some labs by the use of microwave processing. Unfortunately the results are often somewhat inferior to those achieved by formalin fixation of sufficient duration followed by routine processing.

For optimal fixation, the volume of formalin should be at least ten times that of the tissue and it should surround the specimen on all sides. If the specimen floats on the formalin, it should be covered with gauze or towel paper to ensure that it is submerged. Likewise, heavy specimens should optimally be placed on a bed of gauze or towel paper. Fixation occurs at room temperature but 4 °C is better for larger specimens. Formalin fixed tissue cannot be used for frozen section as it results in a peculiar ice crystal distortion.

Zenker's solution is one of the best f ixatives ever devised for l ight microscopic work but it is expensive (incorporating mercuric chloride), requires careful disposal of the mercury, and necessitates meticulous attention to fixation times and washing procedures to remove the precipitates of mercury. This, or sublimate sodium acetate formalin ('B-5'), are often used for biopsies of kidneys, bone marrow, lymph nodes, and testicles.Bouin's fixative contains picric acid, and has been recommended especially for testicular biopsies but Zenker's provides

Fixation of histology specimens.

Dr Rudi Botha 5

pathology forum

fixation - the diagnosis starts here!

specific specimen types and careful attention to the detail described above, not only benefits the pathologist in simplifying his/her task of assessing the slides, but ultimately the patient gets the greatest benefit of all - an accurate diagnosis.

6

pathology forum

Cells lying in free fluid for too long a period of time often undergo severe degenerative changes, which limit accurate diagnosis. If fluids need to be tapped repeatedly, re-accumulation of the fluids often yield more cells which are better preserved and it is recommended therefore that each time an effusion is tapped, a specimen is sent for cytological evaluation if a definitive diagnosis has not been made previously. The specimen is collected by the doctor in a clean, properly labelled container. An equal volume of 50% alcohol is added and may be preserved for 24 - 48 hours with refrigeration.

Gastrointestinal tract preparations:Washings: Deliver on ice immediately to laboratory. Brushings: Brushes should be rapidly rolled on a glass slide. The slides should be immediately fixed or brushes can be transported to the laboratory in 50% alcohol.

Cerebrospinal fluid:The specimen is collected by a doctor in a sterile, properly labelled plastic container as cells adhere to glass. A fresh, unfixed specimen must be transported to the laboratory immediately. Specimens should be processed within 30 minutes and kept at body temperature if possible. If any delay is anticipated, keep specimen in a refrigerator to prevent bacterial growth. Cells are often few in number and do not preserve well in CSF.

Scrapings - skin, tongue, nasopharyngial, pemphigus, ocular, and Tzanck smears, nipple secretions, etc:The material is smeared or rolled directly onto a glass slide, which should be fixed IMMEDIATELY with cytology spray fixative to avoid air-drying artefact and to maintain preservation, by holding the container approximately 30 cm from the glass slide and applying spray for one to two seconds.

Fine needle aspiration:It is important that smears are made after ejecting the needle content onto a clean labelled glass slide. Air dry one (or more) slide(s) and fix one (or more) slide(s) IMMEDIATELY with spray-fix (Cytofix®) by holding the can upright and spraying the material at a distance of 30cm from the slide. Any alcohol-based fixative, even hairspray, can be used. After slides are prepared, the syringe is thoroughly rinsed in a separate specimen container with 50% ethanol. Both the slides and the rinse should be submitted as soon as possible.

The capacity of the pathologist to accurately assess a histology or cytology specimen is influenced by many technical factors, the most important of which and one that can and should at all times be controlled by the referring clinician, is the fixation of the specimen. There are many aspects to correct fixation of

Figure 1 A cytology photomicrographdemonstrating excellent nuclear and cytoplasmic detail on a PAP stained smear of a malignant breast aspirate.

Figure 2 A cytology photomicrographdemonstrating poor nuclear and c y t o p l a s m i c d e t a i l d u e t o degeneration of cells in a poorly fixed smear of a breast aspirate.

7

About 15% occur in the maxilla, usually in the posterior region. These tumours are often asymptomatic causing painless expansion of the jaw. If untreated the lesions will grow slowly often to massive proportions. Pain and paraesthesia are uncommon even in large tumours.

Radiological characteristicsAmeloblastomas begin as unilocular lesions and evolve into multilocular tumours (Fig.2). The locules may be small and numerous and resemble a honeycomb. Larger locules are fewer in number and due to expansion have a “soap-bubble” appearance (Fig.2).

The cortex is significantly thinned and intact, but some may show perforation. Buccal and lingual cortical expansion is frequently present and resorption of tooth roots adjacent to the tumour is common.

Root resorption has a “knife-edge” pattern corresponding to the margin of the neoplasm (Fig.2). When roots are not resorbed they appear to extend into the

rdlesion (Fig.2). An unerupted tooth, usually a 3 molar, is often associated with the radiolucent defect.

Solid ameloblastomas, being epithelial neoplasms, may appear radiographically as unilocular radiolucent lesions and resemble almost any type of cystic lesion. The margins of these lesions often show a scalloped border. There are however several odontogenic and non-odontogenic lesions that may show similar multilocular radiolucent features. Some ameloblastomas have tremendous growth potential (Fig.3) and can mimic malignant bone tumours.

The treatment of solid ameloblastomas is resection of the jaw with a 2 centimeter margin from the radiographic tumour edge. MRI is usually used to plan the resection margins. This is then followed by reconstructive surgery with bone grafting.

Cystic ameloblastomas can sometimes be treated using the marsupialisation technique. Here the size of the tumour is progressively reduced by the weekly removal of the BIPP (bismuth iodoform paraffin paste)-impregnated ribbon gauze until the circumcystic bone has regenerated and the tumour can be enucleated. Subsequent operations may be necessary to remove recurrent tumour, but the integrity of the jaw is maintained.

Introduction

Solid or multicystic intra-osseous ameloblastomas

Ameloblastomas are the most clinically significant tumours of odontogenic epithelial origin. They arise from the dental lamina, enamel organ or possibly from the epithelium of odontogenic cysts. They are s low growing local ly invasive tumours that run a benign course in most cases.

They occur in three different clinico-radiographic situations with di f ferences in therapeut ic management and prognosis:

1. Conventional solid or multicystic - 86% of all cases

2. Unicystic - 13% of all cases3. Peripheral (extra osseous) 1% of all cases

These neoplasms occur in patients over a wide age range.

They are rare in children younger than 10 years and relatively uncommon in the 10 to 19 age group. The tumours show equal prevalence in the 20 to 60 age group and there is no significant gender predilection. South African studies have shown a higher prevalence in blacks.

About 85% of these ameloblastomas occur in the mandible, most often in the

rd3 molar – ascending ramus area (Fig.1).

Prof Vince Phillips

Figure 1 Ameloblastoma. Relative distribution of the tumour in the jaws.

Figure 2 Typical multilocular radiolucency with expansion of the cortex, migration of the teeth and knife-edge root resorption. The roots that are not resorbed appear to project into the tumour.

Figure 3 A massive ameloblastoma with expansion of the cortex andbony trabeculae within the tumour mimicking an osteosarcoma.

Figure 4 The unicystic ameloblastoma in a young child causing massive expansion of the mandible extending into the ramus and surrounding the crown of the 1st permanent molar tooth. Note the kni fe -edge resorption of the root of the deciduous molar tooth (arrow).

pathology forum

ameloblastoma

8

pathology forum

Unicystic ameloblastomas

Histology of ameloblastomas

Peripheral (extra-osseous) ameloblastomas

These account for 10% to 15% of all intra-osseous ameloblastomas. The tumours may arise as de novo neoplasms or from non-neoplastic cysts. The average age is 23 years and 50% occur in the 2nd decade. About 90% occur in the posterior mandible. These tumours result in painless swelling of the jaw.

Radiologically it usually appears as a circumscribed radiolucency surrounding the crown of an unerupted tooth (Fig.4) and can mimic a dentigerous cyst. Unicystic ameloblastomas can radiologically also resemble other cystic lesions such as a primordial or residual cyst. The marsupialisation technique is used to treat these lesions.

It is therefore important to accurately diagnose the histological type of an ameloblastoma to indicate to the surgeon whether marsupialisation can be instituted and thereby save the jaw or whether resection of the jaw is necessary.

Solid or multicystic ameloblastomas have a tendency to undergo cystic change.Follicular and plexiform patterns are the most common (Figs. 5-7). Less common patterns are the acanthomatous, granular cell, basal cell and desmoplastic types.

Unicystic ameloblastomas have 3 variants: Luminal: tumour confined to the luminal surface of the cyst (Fig. 8) Intra-luminal: nodules of the ameloblastoma project from the cystic lining

into the lumen. Mural: the fibrous wall of the cyst is infiltrated by typical follicular or

plexiform ameloblastoma.

These are usually painless, non-ulcerating sessile or pedunculated gingival or alveolar mucosal lesions. Most of them resemble a fibrous epulis. The average age reported is 52 years. Histologically they show islands of ameloblastic epithelium. These lesions have been misdiagnosed as basal cell carcinoma of the oral mucosa. Most lesions are successfully treated with local surgical excision. Recurrence is reported in 15% of cases and rare cases have undergone malignant change.

ReferencesNeville BW, Damm DD, Allen CM, Bouquot JE. Oral &

ndMaxillofacial Pathology. 2 ed. WB Saunders. Philadelphia. 2002.Raubenheimer EJ, van Heerden WFP, Noffke CEE. Infrequent clinico-pathological findings in 108 ameloblastomas. J Oral Pathol Med 24:227-232, 1995.Langlais RP,Langland OE & Nortjé CJ. (1995) Diagnostic Imaging of the Jaws. Williams & Wilkins. Baltimore

Figure 5 Follicular ameloblastoma showing islands of epithelium that resemble enamel organ epithelium in a fibrous stroma. The epithelial nests contain a core of stellate reticulum and pallisading of the peripheral cells with reverse polarity.

Figure 6 Follicular ameloblastoma showing cystic degeneration of the stellate reticulum.

Figure 7 Plexiform ameloblastoma with large anastomosing cords of odontogenic epithelium with cystic degeneration of the connective tissue.

Figure 8 Unicystic ameloblastoma (luminal type). The cyst is l ined by ameloblastic epithelium showing a polarized basal layer with overlying loosely cohesive epithelial cells resembling stellate reticulum.

Drs Dietrich, Voigt, MiaVennote Partners

and increased volumes as a result of In all the laboratories the specimens are amalgamations have enabled more cost processed by the most technologically effective provision of quality pathology at advanced and automated laboratory affordable prices. This has also enabled equipment. PathCare to perform high technology specialised testing at our central reference The new Reference Laboratory at N1 City laboratory. near Cape Town is equiped with a state-of-

the-art automated line that can analyse up The fact that the Group has more than 77 to 300 specimens an hour.

PathCare is the trademark of an associated pathologists means that we have vast group of individual private pathology specialist expertise available. Specimens from hospitalised patients laboratories in South Africa and Namibia requiring urgent analysis can be dealt with which over the last decade and a half have Amalgamations have also allowed us to in PathCare peripheral laboratories amalgamated to form the Pathcare Group. form a national grid. The Group comprises situated within many major private

of approximately 60 pathology laboratories hospitals, and in close proximity to their The Group is focused on delivering quality and 110 specimen-collecting depots, with intensive care units. The majority of our diagnostic pathology testing in the most its head office at N1 City, near Cape Town. laboratories provide a 24 hour service.cost effective way. The laboratories and depots are spread Pathology is essentially a volume business over South Africa and Namibia.

110 specimen collecting depots

24 hour service

77+ pathologists

+/- 60 pathology laboratories

2