J Clin Pathol 1988;41:871-874

Silver deposition in the cervix after application ofsilver nitrate as a cauterising agent

D G LOWE, D A LEVISON, P R CROCKER, J H SHEPHERD*

From the Departments ofHistopathology and *Gynaecology, St Bartholomew's Hospital, London

SUMMARY Large amounts of metallic silver pigment were found in 10 cervical biopsy specimenstaken for the histological grading of cervical intraepithelial neoplasia (CIN). The assessment ofCINwas made much harder because the pigment obscured the morphological detail of the epithelial cells,and in some it was very difficult to determine whether koilocytosis or CIN I was present. The silvercan easily be removed by a simple chemical method.

In several biopsy specimens of cervical tissues takenfor the histological grading of cervical intraepithelialneoplasia (CIN), variable amounts of granular brownpigment were found. The gynaecologists who hadperformed the biopsies were unable to suggest a reasonfor the pigment deposition-the only common factorthat they could identify was that iodine solution hadbeen applied to all of the cervices before biopsy.

Assessment of the epithelial aspects of the biopsywas difficult as the pigment overlay the epithelial cells(fig 1). It was decided to analyse the material by x-rayenergy dispersive spectroscopy as an initial steptowards its removal from tissue sections.

Material and methods

Routinely processed haematoxylin and eosin stainedparaffin wax sections from 10 cervical biopsyspecimens that were found to have large amounts ofbrown granular pigment in and between the epithelialcells of the squamous ectocervical mucosa wereexamined by x-ray energy dispersive spectroscopy.The 10 cases were collected from the routinegynaecological material over a period of five weeks,and the patients' ages ranged from 25-38 years (mean29 years).The methods used have been describod in detail

elsewhere'2 but briefly, comprise removal of thecoverslip, coating of the section with carbon in aNanotech CC2 carbon coater, and examination of thesection in a Jeol 35 CF scanning electron microscopeequipped with a backscattered electron detector, aKevex Unispec System 7000 x-ray energy dispersivespectroscopy unit, and an Apple Microplus data

Accepted for publication 17 March 1988

processor. All specimens were examined at 15 KV forperiods of 100 seconds.

In view of the spectroscopy findings, removal of the

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872pigment was attempted with a 4:1 mixture 5%aqueous solution of sodium thiosulphate and 0-5%aqueous potassium ferricyanide, in which the sectionswere immersed for five minutes.3 The sections werethen stained with haematoxylin and eosin and moun-ted routinely.

Cautery with a silver nitrate pencil (Avoca Phar-maceutical Products Ltd, UK, product licence number4286/0004) was applied to fresh cervical tissueremoved at hysterectomy for uterine leiomyomas;there was no clinical indication of cervical disease, andhistological sections of the treated areas wereexamined after removal ofthe silver deposit to confirmthat no lesions were present. The pencils were held incontact with the ectocervical epithelium for periods offive seconds, 10 seconds, 30 seconds, one minute, twominutes and five minutes. The specimens were thenwashed in formol saline and fixed in formalin. Tissuefor transmission electron microscopy was taken fromthe specimen in contact with a silver nitrate pencil for30 seconds.A 3% solution of iodine in potassium iodide is used

routinely at this hospital to delineate abnormal epith-elium (modified Schiller test).' Biopsy specimensfrom five cervices to which this solution had beenapplied were treated in the same way as those in which

Lowe, Levison, Crocker, Shepherd

brown pigment was found, to investigate whether thismight be related to the brown deposit.Results

X-RAY ENERGY DISPERSIVE SPECTROSCOPY (XES)Analysis of all ofthe cervical biopsy specimens showedthat the predominant element present in the brownpigment was silver. Chlorine was also present and insome cases there were traces of iodine (figs 2a and b).XES of one of the silver nitrate cautery sticks inroutine use in the gynaecology clinics showed silver,potassium, and traces of chlorine. Analysis of thecervical tissues treated in vitro with the silver nitratestick showed only silver and chlorine in the tissues.The cervical biopsy specimens painted in vitro withiodine solution showed traces ofiodine alone; no silverwas present.

LIGHT MICROSCOPYSilver deposition in cervical tissues was found his-tologically to consist of mid-brown to dark-brownpigment lying within and between epithelial cells (figs 1and 3). The pigment was present in the epithelium towhich silver nitrate cautery was applied, in theimmediately adjacent mucosa, and in the stroma in

I

Fig 2a Backscattered electron image ofsilver-treatedcervical epitheliwn. Bright lines in upper halfoffieldcorrespond to dark lines ofsilver deposit seen on lightmicroscopy.

Fig 2b x-ray energy dispersive spectrograph ofone ofthe bright areas showing silver and chlorine.

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Silver deposition in the cervix

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Fig 3 Silver deposition has occurred in upper levels ofectocervical epithelium and there is accumulation ofpigmentin a line in the intermediate cell zone. (Haematoxylin andeosin.)

some cases.In the stratified squamous epithelium of the

ectocervix of the biopsy specimens pigment was foundbetween the superficial and intermediate zone cells,and where deposition was extensive, was presentbetween and within parabasal and basal cells. In mostcases the mucosa was spongiotic, and in some this wassevere. The intercellular oedema emphasised thepresence of discrete silver granules between thesquamous cells.Where diffusion of the silver had occurred through

the mucosa into the underlying stroma, there washeavy deposition on the basement membrane. Whensilver nitrate was applied to the simple columnarepithelium of the endocervix and portio, relativelylittle pignent was deposited in the epithelium andmore was found in the stroma below it. Deposition onthe basement membrane was especially prominentbelow columnar epithelium. Blood vessels in thestroma showed fibrin deposition and clumping of redcells.

873

In the cervical specimens to which silver nitrate wasapplied experimentally, the level of penetration of thesilver pigment corresponded to the length of time ofapplication of the silver nitrate stick. After periods offive and ten seconds pigment was present only in thesuperficial layers of the mucosa; after 30 secondspigment had reached the intermediate layers and theparabasal cells; and after two minutes the basal cellsand immediately subjacent stroma were affected. Theextent of deposition of silver seemed to depend simplyon the rate of diffusion of silver nitrate in solution.Spongiosis was present in specimens treated with thecautery stick for one minute or longer.Removal of the silver by sodium thiosulphate/

potassium ferricyanide solution clearly showed theunderlying squamous cells. In the biopsy specimenstreated for up to one minute the grade ofCIN could beassessed as easily as if silver nitrate had not beenapplied. In the cases to which silver nitrate had beenapplied for two and five minutes, the severity of thespongiosis made assessment of CIN very difficult asthe nucleus:cytoplasm ratio of the epithelial cells hadbeen changed.

Neither in vivo nor in vitro application of3% iodinesolution to cervical epithelium caused any appreciablehistological change. In the cases treated with bothiodine solution and silver nitrate there was noapparent additive effect of the iodine on the amount ofpigment deposition.

TRANSMISSION ELECTRON MICROSCOPYTransmission electron microscopic examination of theaffected tissues confirmed the light microscopicalfindings that most of the silver was deposited betweenthe epithelial cells. Smaller amounts were scatteredrandomly in the cytoplasm of the squamous cells andhad no apparent association with organelles. Thesevere spongiosis in places had resulted in rupture ofdesmosomal connections and separation of squamouscells from their neighbours, but there was no evidenceof spongiotic vesicle formation.

CLINICAL CORRELATIONWhen the results of the spectroscopic analysis wereknown, the surgical pathology cases were reviewedwith the clinicians. It became apparent that all of thecases containing pigment we almost certainly takenas second or subsequent bit ;y specimens after thehaemorrhage caused by the nrst biopsy had beenstanched with a silver nitrate stick.

Discussion

The common practice of applying a silver nitrate stickto cervices after biopsy to stanch the haemorrhagefrom the biopsy site can lead to large amounts of silver

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874 Lowe, Levison, Crocker, Shepherd

being deposited in the epithelium and stroma of thecervix. It can also cause spongiosis of the squamousmucosa of the ectocervix. There was little chance thatthe spongiosis might be attributed to an inflammatorycause, as silver granules were obvious in all of thetissues with spongiosis. The degree ofspongiosis in ourcases was similar to that described by Benda and co-workers7 as a result of application of strong (5%)iodine solution to the cervix.

Silver nitrate application did not produce the cyto-plasmic eosinophilia, loss of chromatin detail andpoor delineation of nuclei and nucleoli described aftercolposcopic treatment with strong iodine solution,and there was therefore not the same risk ofconfusionbetween squamous metaplasia and dysplasia. It wasinteresting that the 3% iodine solution used in thisstudy did not induce the artefactual changes foundafter treatment with 5% iodine solution. The pigment,on the other hand, can cause diagnostic difficulties byobscuring the detail of the underlying mucosal cells.Once it is recognised as silver, it can easily be removedby a simple thiosulphate/ferrocyanide method.

Our thanks and compliments are due to Dr G Philipof Kingston Hospital, Kingston-upon-Thames,England, who recognised without the benefit of x-ray

spectroscopic analysis that the brown pigment wassilver.

References

1 Crocker PR, Toulson E, Levison DA. Particles in paraffin sectionsdemonstrated in the backscattered electron image (BEI).Micron 1982;13:437-46.

2 Levison DA, Procker PR, Lee G, Shepherd NA, Smith A.Unexpected inorganic elements in oral lesions: results of X-rayenergy spectroscopy (XES) on particulate matter in paraffinsections. J Pathol 1984;144:1 19-29.

3 Bancroft JD, Cook HC, eds. Manual of histological techniques.Edinburgh: Churchill Livingstone, 1984:157.

4 Schiller W. Early diagnosis ofcarcinoma of the cervix. Surg ObstetGynecol 1933;56:210-22.

5 Schiller W. Early diagnosis of carcinoma of the portio uteri. Am JSurg 1934;26:269-80.

6 Rubio CA, Thomassen P. A critical evaluation of theSchiller test in patients before conization. Am J Obstet Gynecol1976;125:96-9.

7 Benda JA, Lamoreaux J, Johnson SR. Artifact associated with theuse of strong iodine solution (Lugol's) in cone biopsies. Am JSurg Pathol 1987;11:367-74.

Requests for reprints to: Dr D G Lowe, Department ofHistopathology, St Bartholomew's Hospital, West Smith-field, London EClA 7BE, England.

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