leprosy inperipheral nerves: histopathological findings in ...leprosy in peripleral nerves:...

Jocurnal of Neurology, Neurosurgery, and Psychiatry, 1980, 43, 198-204

Leprosy in peripheral nerves: histopathologicalfindings in 119 untreated patients in NepalJ C PEDLEY, D J HARMAN, H WAUDBY, AND A C McDOIUGALL

From the United Mission Hospital, Tansen, Palpa, Nepal, the Leprosy Study Centre, London,and the Slade Hospital, Oxford

S UMM AR Y From a series of 342 nerve biopsies taken by one clinician over a period of 12 years

in Nepal, this paper describes the histopathological findings in 153 biopsies from 119 patientssuffering from tuberculoid, borderline (dimorphous) or lepromatous leprosy, who were untreatedat the time of first presentation and diagnosis. They were taken during the course of other studies,mainly concerned with the mode of transmission of leprosy, and which included biopsies of skin,dartos muscle, nasal mucous membrane and nipple, results of which have already been published.Examination of serial sections by light microscopy revealed a density of cellular infiltration innon-lepromatous cases, or of bacilli in macrophages and Schwann cells in lepromatous cases,

which was marked in degree and usually widespread fiom one end of the biopsy to the other.Intraneural caseation was recorded in four patients with tuberculoid or borderline-tuberculoidleprosy, and many others in this part of the spectrum showed extensive disruption of perineurialand endoneurial structure. In lepromatous patients, the numbers of bacilli in the endoneurial area

not infrequently exceeded one thousand per oil immersion field. Although well known to histo-pathologists familiar with this disease, it is considered that the significance of these findings, inpatients presenting for the first time, is not well appreciated by those working in general medicine,neurology, epidemiology, or even in leprosy control.

There are very few organisms which enterperipheral or dermal nerves, and amongstmycobacteria, the leprosy bacillus is unique inthis respect. Since the early days of clinicalobservation in leprosy, it has been obvious thatnerves are heavily involved and some authorshave stated that neural tissues, and particularlySchwann cells, are the most heavily and con-sistently affected; others consider that bacillifirst enter nerves in the genesis of all leprouslesions, and that they persist in them long afterdisappearance from other tissues as a result oftreatment. Various aspects of neuropathy inle-prosy have already been well described;publications from recent years have dealt withthe clinical findings.17 The histopathologicalfeatures have been particularly well reviewedby Weddell and Pearson22 and the present paperdoes not attempt to add new knowledge to thisaspect of leprosy neuropathy or to sh.ed new

Address for reprint requtsts Dr AC McDougall, The SadeHospital, Headington, Oxford OX3 7JH.

Accepted 14 October 1979

light on its pathogenesis. It does, however, setout to illustrate a fact which is not always wellunderstood even by those working in leprosy-namely that in this disease on first presentationfor diagnosis, the patient's peripheral nerves mayalready be heavily infiltrated with defensive cells,or infected by large numbers of bacilli. Wereport the extent and severity of this involve-ment in nerve biopsies from 119 patients withvarious forms of leprosy in Nepal, who werecompletely untreated on first presentation.

Patients and Methods

The patients were under the care of one of us(JCP) at the United Mission Hospital, Tansen,Palpa, Nepal, during the 12 years 1962 to 1974.They were mainly out-patients, and almostentirely self-reporting, apart from a smallnumber, perhaps 10 per cent of the total, whowere found to have leprosy as a result of exam-ination of household or family contacts. Theycame on foot over the mountains, covering 15to 20 miles a day, from distances up to 200

198

Protected by copyright.

on May 15, 2021 by guest.

http://jnnp.bmj.com

/J N

eurol Neurosurg P

sychiatry: first published as 10.1136/jnnp.43.3.198 on 1 March 1980. D

ownloaded from

http://jnnp.bmj.com/

1'99Leprosy in peripleral nerves: histopathological fin,dings inl 119 untreated patienits is, Nepael

miles from the hospital. From the total of 342biopsies in the 12-year period, including bothtreated and untreated patients, there were 302men and 40 women, a difference which may bepartly accounted for by the simple fact thatwomen work so hard in Nepal that they do nothave time to attend. Some patients were

admitted for a few days or weeks, but for themost part they were examined and assessed as

out-patients. Treatment was in the form of oraldapsone (DDS) in a dose of 50 to 100 mg dailyand usually enough was given for three months,though in the case of those living at great dis-tance, a year's supply was given at a time. In1962, the default rate, defined as nonattendancefor a year or more, was in the region of 30 percent, and by the end of the study (1974) it was

25 per cent.Selection of patients: The total of leprosypatients registered and under supervision at thehospital during the period of study was approxi-mately 5500, from whom biopsies of peri-pheral nerve were taken as part of a largerseries of studies, mainly concerned with modeof transmission of leprosy.f23-7 Of the total of342 biopsies, 173 were from treated leprosypatients, and 16 were taken for other diagnosticpurposes, but from patients with no clinical or

other evidence of leprosy; these are not describedin the present paper. The remaining 153 biop-sies came from 119 patients who were completelyuntreated on first presentation, and their clas-sification, based on history, clinical findings,lepromin test, slit-skin smears, skin biopsy,and on the nerve biopsy itself is shown inthe table, the system of classification, includinginterpretation of the lepromin test, being thatof Ridley and Jopling.2" The term lepromatousis used here to include both polar (LLp) andsub-polar (LLs) patients (the latter being a sub-group of lepromatous leprosy, identified histo-logically and clinically by Ridley and Waters in1969,"9 tending to 'reverse' (upgrade) to a

horderline-lepromatous (BL) classification on

treatment). The lepromin was of Mitsuda type,standardised to WHO specification to contain1-6 x 10' acid-fast bacilli per ml.Nerve biopsy technique: The selection of nerves

for biopsy depended largely on the clinical find-ings; several patients had more than one biopsy ofskin or nerve or both in order to collect dataon the classification and state of activity oflesions in different parts of the body on firstpresentation. Sensory nerves only were chosenand they were usually either visible or palpableclinically (or both), the most commonly used

being the greater auricular on the side of theneck, the terminal radial or the terminal ulnarat the wrist, less commonly the superficialperoneal or the sural nerve in the leg. Thedetails of biopsy technique have recently beendescribed in full"3 and it is here only necessaryto add that a high success rate was ensured by1: adequate exposure of the nerve under goodlight, 2: the use of a nerve hook to bring the nervegently out of the wound, 3: the removal of anadequate length of nerve tissue, the incisiongoing down far enough to include at least partof a bundle, and 4: inspection of the cut end ofevery nerve biopsy with a hand lens to ensurethat it did contain nerve fibres. From the totalof 153 biopsies, only five (3 3 per cent) failedto reveal nerve tissue, one consisting of bloodvessel wall. No patient registered complaintsdirectly related to the procedure, and on follow-up, in many cases for five years or more, therewas no evidence that the procedure itself hadled to neuritis or deterioration in sensoryfunction in the area concerned.Fixation, processing and staining: Biopsies werefixed in a modified formol-Zenker solution for15 to 24 hours, then transferred to 70% alcohol,embedded in paraffin wax and cut, in longitudinaland transverse planes at 5 im. Staining was witha combined Fite-Faraco modification of Ziehl-Neelsen and a trichrome ('TRIFF').

Results

These are summarised in table 1. Apart fromthe five biopsy 'failures' noted above, and sixother tissues which showed nonspecific changes(and were not diagnostic of any form of lep-rosy), nine biopsies were completely normal.

Table 1 Classificat,on (Ridley and Joplin, 1966) ofthe type of leprosy in 153 nerve biopsies fromuntreated patients

Tvpe of leprosy Number of biopsies

Tuberculoid (TT) 13Borderline-Tuberculoid (BT) 20Borderline (BB) 18Borderline-Lepromatous (BL) 60*Lepromatous (LL) 33*

Patients with leprosy (clinically and bacteriologicallyproven) in whom the biopsy:(I) revealed normal nerve tissue 9(2) failed to reveal nerve tissue (blood vessel or

connective tissue, taken by mistake) 5(3) Revealed only nonspecific damage 6

*These comparatively high figures for BL and LL leprosy do notnecessarily reflect the situation for the country or even the areaserved by this hospital. The lepromatous rate for Nepal generally36is 20',.



http://jnnp.bmj.com

/J N

eurol Neurosurg P


ownloaded from


J C Pedley, D J Harman, H Waudby, and A C McDougall

These 20 were in fact all from patients in whomthe clinical signs and skin histopathology werenevertheless diagnostic of borderline (dimor-phous) leprosy, and the normal or nonspecificfindings were considered compatible with thepatchy and often asymmetrical distribution oflesions which typically occurs in forms of leprosyintermediate between the tuberculoid and lepro-matous poles. In all patients with abnormal find-ings in the nerve biopsy, the skin biopsy was alsoabnormal and in every instance the type (clas-sification) of leprosy was in agreement. Thelepromin test was uniformly negative in alllepromatous (LLp and LLs) and borderline-lepromatous (BL) cases; results in non-leproma-tous cases accorded with those already describedin detail for patients in other parts of the spect-rum.28

Lepromatous (LLp and LLs) biopsiesAll 22 showed large numbers of bacilli, someof them in globus arrangement, scattered

.;:~s < .;: 'Z

-"R

............

throughout the epineurial, perineurial and endo-neurial areas (figs 1 and 2). Most were in macro-phages or Schwann cells, but perineurial cells andfibroblasts were also involved. In many casesbacilli, often as globi, were seen in the cytoplasmof endothelial lining cells of neural vessels (fig 3).The morphology of a high percentage of free-standing bacilli as seen in sections was solid-staining throughout their entire length, a findingwhich has been equated with viability.32 Inseveral biopsies, the numbers of bacilli exceeded1000 per oil immersion field, and they were notinfrequently so dense and numerous as to beuncountable.

Borderline-lepromatous (BL) biopsiesAll 60 showed considerable numbers of bacilliand infiltrating cells, together with disturbanceof normal perineurial and endoneurial structure,and here again the changes were widespreadthroughout the tissue biopsy. There were, notinfrequently, areas of inflammatory oedema

* Fig 1 Dorsal cutaneous branch of right ulnarnerve at wrist. LL leprosy. Longitudinal section.E= epineurium. Perineurium is hard to distinguishand the bulk of tissue shown consists ofendoneurium, in which macrophages and Schwann

~;cells contain large numbers of Mycobacteriumleprae. TRIFF stain. Original magnification x 250.

2w'q^^A) `* .1;Mw, A... ...... *,,j< . US .i..7t x.'i'ii,'

A~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~A

jr~~~~~~~*

200



http://jnnp.bmj.com

/J N

eurol Neurosurg P


ownloaded from


Leprosy in peripheral nerves: histopathological findings in 119,,untreated patients in Nepal

Fig 2 Same biopsyas fig 1. Theendoneurial zonecontains largenumbers of bacilli,many of them solid-staining, inmacrophages andSchwann cells. Thereare numerous globi(arrowed) containinguncountable numbersof bacilli. TRIFFstain. Originalmagnification x 1000.

associated with infiltrating cells in the endo-neurial area. Despite the lower concentrations ofbacilli in this group, compared with the LLgroup described above, the disturbance of neuralstructure revealed by histopathological examina-tion was invariably greater, and the significanceof this, in relation to the often widespread in-volvement of nerves recorded clinically, will bediscussed below.

Borderline (BB) biopsies (18 cases)Bacilli were present in moderate numbers, witha predominant epithelioid cell infiltrate, togetherwith a small element of lymphocytes; abnormallamination of the perineurium was present inseveral cases as already described.33 Once again,most of these 18 biopsies showed changes whichoccupied the entire extent of the tissues presentedfor examination.

Fig 3 Same biopsyas figs and 2.medium sized

^.i.llarteriole in theepineurium containsmany bacilli in endo-thelial lining cellsF. ; f (arrowed). TRIFF

* stain. Originalmagnification x 1000.

201

-.Nom- -,-- '""I

".1

I-A

. 1.

,4. Al

-( -I" i.......

.."W. idNMIN

...,

'llillikellillow .4wI w

.0, -%L !k

*t'A

i



http://jnnp.bmj.com

/J N

eurol Neurosurg P


ownloaded from


J C Pedley, D J Harinani, H Wau,dbv, acnd( A C McDougall

Borderline-tuberculoid (BT) and Tuberculoid(TT) biopsies (33 cases)These showed a densely packed infiltrate ofgranulomatous cells from one end to the other.In many instances, subdivision into epineurial,perineurial and endoneurial areas was obliter-ated, and Schwann cells, myelin and axons couldnot be clearly identified over large areas. Bacilliwere typically few in number in BT, and evenfewer in TT patients, though they were in factidentified in all biopsies except four out of the33 in this combined group. Abscess formationwas found in the endoneurial area in fourpatients, two with BT and two with TT leprosy;in one instance (fig 4a and b, fig 5), the necroticarea occupied approximately 50% of the speci-men and had obviously destroyed all neuralelements over an area several mm in diameter.

Discussion

It bears repetition that these findings were re-corded in the peripheral nerves of patients onfirst presentation for diagnosis and treatment. Inthe lepromatous (LL) forms, the sheer bulk ofbacilli may be disruptive or even space-occupying(fig 2), but their presence, at this anergic endof the spectrum, does not give rise to cell-mediated immune responses which are in them-selves damaging, as occurs in the tuberculoid andborderline forms of this infection. However,either before or after treatment, bacilli in lepro-

matous leprosy may become antigenic andprovoke an immune-complex reaction, commonlycalled erythema nodosum leprosum (ENL)because of its frequent involvement of the skin,although numerous other tissues may be affected,including nerves.4 12 A further point of concernabout the invasion of nerves by Mycobacteriumleprae, is that it may be able to survive withinSchwann cells for relatively long periods,22 andalso despite the administration of adequate drugtherapy over a period of many years.34 In border-line-tuberculoid (BT) and tuberculoid (TT)leprosy on the other hand, the influx of infiltrat-ing cells in response to relatively small numbersof bacilli may create a battlefield in vitally im-portant tissue. In this area of the spectrum,cell-mediated immune responses are in fact themain mechanisms involved in tissue destruction."A point of some interest which arises from thepresent study concerns the classification of thosepatients, who, on consideration of the combinedclinical and histopathological findings (and clini-cal photographs, when available) were worstaffected neurologically. Tissue necrosis, such asthat illustrated in figs 4 and 5, occurred in tuber-culoid (TT) or borderline-tuberculoid (BT)patients, and was clearly disastrous in the area ofnerve concerned, but it was localised. Consider-ing the factors of numbers of bacilli, numbers ofinfiltrating cells, physical disruption of endo-neurial and perineurial structure, together withthe clinical and photographic evidence, the

:''.r2X . .- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~...

.........~~~~~~~ ~~~ ~~ ~~ ~~ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

7K.~ ~ ~ -,

Fig 4 Superficialradial nerve at wrist.BT leprosy: longi-tudinal section. Thereis extensive tissuenecrosis (N) in theendoneurial zone andthe perineurium isheavily infiltrated byhistiocytes, lympho-cytes and a feew giantcells. Bacilli were notfound. TRIFF stain.Original magnificationx 25.

202



http://jnnp.bmj.com

/J N

eurol Neurosurg P


ownloaded from


Leprosy in peripheral nerves: histopathological findings in 119 untreated patients in Nepal

*! - '*b,<^,*4.. *'' -.4*

f.s1 v 4

-.=. F-, . * s S + s A4

-.5..~~~~~~~~akFig 5 Same biopsyas fig 4. BT leprosy.In the centre of theendoneurial zonethere is an area oftissue necrosis (N),surrounded by intensehistiocyte-lymphocyteinfiltrate. TRIFFstain. Originalmagnification x 160.

patients who had the most severe and widespreadneurological damage in this study were in theborderline-lepromatous (BL) group. We believethis to be due to the unfortunate association oftwo factors-a fairly widespread (thoughnot necessarily complete and symmetrical) seed-ing of peripherzl nerves with bacilli, and arotential on the part of the immunologicallyunstable BL patient to produce, within nerves(and elsewhere), a cell-mediated immune responsewhich may in itself be damaging. It may berelevant that levels of IgG in the serum haverecently been shown (Samuels, personal com-munication, 1979) to be highest, not in leproma-tous (LL) but in borderline-lepromatous (BL)patients.As regards symptomatology in lepromatous

leprosy, it should be emphasised that by nomeans all the patients whose biopsies are ana-lysed in this study had symptoms referable to thenerve biopsied, or the peripheral nerves gener-ally. Indeed, as in other parts of the world, themore lepromatous the findings, in general theless marked were the symptoms. By the timethese outset biopsies of peripheral nerve weretaken, all lepromatous patients in this series hadpcsitive skin smears for leprosy bacilli frommultiple sites, together with highly positivesmears from the nasal mucus. In considering allthe practical problems of diagnosing and treating

lepromatous leprosy at an early stage, it is prob-ably significant that those who attended weremainly men who had the determination to walklong distances to the hospital for diagnosis, andit is possible that they represent in Nepal, as inmany other countries, only the tip of an "ice-berg" of infection of much greater size.The present data, taken from experience of

one observer only, underline the clinical andtherapeutic problems attendant upon neural in-vasion in leprosy. In this tissue, bacilli seem tofind ideal conditions for multiplication and vitalstructures may be damaged if their presencegenerates immunological reactions. The treatmentof the bacillary infection in nerves is still farfrom satisfactory, and prevention and treatmentof adverse reactions under field conditions incountries like Nepal, including the use of drugssuch as thalidomide and the steroids, is fraughtwith difficulties. What appears "early" clinicallyin leprosy may be disturbingly late on histopatho-logical examination of a nerve biopsy.

We are indebted to Dr SG Browne, Directorof the Leprosy Study Centre, for permission toexamine clinical records and refer to histopatho-logical reports. AC McDougall is supported bythe British Leprosy Relief Association (LEPRA)and a grant from the Oxfordshire Area HealthAuthority (Teaching).

B

203



http://jnnp.bmj.com

/J N

eurol Neurosurg P


ownloaded from


J C Pedley, D J Harman, H Waudby, and A C McDougall

References

I Browne SG. Some less common neurologicalfindings in leprosy. International Journal ofLeprosy 1965; 33:881-91.

2 Browne SG. Leprosy-clinical aspects of nerveinvolvement. In: Hornabrook RW, ed. Topics onTropical Neurology, 1975.

3 Crawford CL. Neurological lesions in leprosy.Leprosy Review 1968; 39:9-13.

4 Karat ABA, Furness MA, Karat S, Rao PSS.Patterns of neurological involvement in relationto chronic and/or recurrent erythema nodosumleprosum. Leprosy Review 1969; 40:49-53.

S Sabin TD, Ebner JD. Patterns of sensory loss inlepromatous leprosy. International Journal ofLeprosy 1969; 37:239-48.

6 Karat S, Rao PSS, Karat ABA. Prevalence ofdeformities and disabilities among leprosy patientsin an endemic area. International Journal ofLeprosy 1972; 40:265-270.

7 Flirness MA, Ranney DA. Nerve enlargement inrelation to classification of leprosy. LeprosyReview 1971; 42:208-18.

8 Iyer CGS. Predilection of Mycobacterium lepraefor nerves; neurohistopathologic observations.International Journal of Leprosy 1965; 33:634-45.

9 Job CK, Desikan KV. Pathological changes andtheir distribution in peripheral nerves in lepro-matous leprosy. International Journal of Leprosy1968; 36:257-70.

10 Dastur DK, Pandya SS, Antia NH. Nerves in thearm in leprosy. 2: Pathology, pathogenesis andclinical correlations. International Journal ofLeprosy 1970; 38:30-48.

11 Skinsnes OK, Yamashiro KM. Morphology andpathogenesis of peripheral nerve involvement inleprosy. US-Japan Cooperative Medical ScienceProgram. International Journal of Leprosy 1970;38:351-2.

12 Job CK. Pathology of peripheral nerve lesions inlepromatous leprosy-a light and electron micro-scope study. International Journal of Leprosy1971; 39:251-68.

13 Sunderland S. The internal anatomy of nervetrunks in relation to the neural lesions of leprosy.Brain 1973; 96:865-88.

14 Antia NH. Significance of nerve involvement inleprosy. Plastic and Reconstructive Surgery 1974;54:55-63.

15 Nishiura M. Electron microscopic basis of thepathology of leprosy. International Journal ofLeprosy 1960; 28:357-400.

16 Dastur DK, Ramamohan Y, Shah JS. Ultra-structure of lepromatous nerves. Neural patho-genesis in leprosy. International Journal ofLeprosy 1973; 41:47-80.

17 Job CK. Mycobacterium leprae in nerve lesionsin lepromatous leprosy. Archives of Pathology1970; 89:195-207.

18 Kahn P, Scott T. The pathology of radial nerve

biopsy in leprosy; a light and electron microscopestudy. Journal of Pathology 1974; 114:97-100.

19 Dash MS. A study of the conduction velocity ofsensory fibres of the ulnar nerve in leprosy.International Journal of Leprosy 1967; 35:460-9.

20 Verghese M, Ittamani KV, Satyanaryana KR,Mathai R, Bhakthavizim CA. A study of theconduction velocity of the motor fibres of ulnarand median nerves in leprosy. InternationalJournal of Leprosy 1970; 38:271-7.

21 Naafs B, Pearson JMH, Baar AJM. A follow-upof nerve lesions in leprosy during and afterreaction using motor nerve conduction velocity.International Journal of Leprosy 1976; 44:188-97.

22 Weddell AGM, Pearson JMH. Leprosy-Histo-pathologic aspects of nerve involvement. In:Hornabrook RW, ed. Topics on tropical neur-ology. Philadelphia: F A Davis Company, 1975.

23 Pedley JC. Presence of M. leprae in human milk.Leprosy Review 1967; 38:239-42.

24 Pedley JC. Presence of M. leprae in the luminaof the female mammary gland. Leprosy Review1968; 39:4, 201-2.

25 Pedley JC. Composite skin contact smears: amethod of demonstrating the non-emergence ofM. leprae from intact lepromatous skin. Lepro.syReview 1970; 41:31-43.

26 Pedley JC. The nasal mucus in leprosy. LeprosyReview 1973; 44:33-5.

27 Pedley JC, Geater JG. Does droplet infectionplay a role in the transmission of leprosy?Leprosy Review 1976; 47:97-102.

28 Ridley DS, Jopling WH. Classification of leprosyaccording to immunity. A five-group system.International Journal of Leprosy 1966; 34:255-73.

29 Ridley DS, Waters MFR. Significance of Varia-tions within the Lepromatous Group. LeprosyReview 1969; 40:143-52.

30 Harman DJ. Biopsies in leprosy. Leprosy Review1975; 46:125-34.

31 Wheeler EA, Hamilton EG, Harman DJ. Animproved technique for the histopathologicaldiagnosis of leprosy. Leprosy Review 1965; 36:37-9.

32 Rees RJW, Valentine RC. The appearance ofdead leprosy bacilli by light and electron micro-scopy. International Journal of Leprosy 1962;30:1-9.

33 Ridley DS. Histological classification and theimmunological spectrum of leprosy. Bulletin ofthe World Health Organisation 1974; 51:451-65.

34 Waters MFR, Rees RJW, McDougall AC,Weddell AGM. Ten years of dapsone in lepro-matous leprosy; clinical, bacteriological and his-tological assessment and the finding of viablebacilli. Leprosy Review 1974; 45:288-98.

35 Godal T. The immune system as benefactor andtroublemaker; the case of leprosy. Lab-Lore 1974;6:305-8.

36 WHO. Leprosy Weekly Epidemiological Record.No 3, 1979; 17-23.

204



http://jnnp.bmj.com

/J N

eurol Neurosurg P


ownloaded from


leprosy inperipheral nerves: histopathological findings in ...leprosy in peripleral nerves:...

Documents